[{"Name":"Systems of Gas Exchange","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Gas Exchange Through the Skin and Gills","Duration":"5m 50s","ChapterTopicVideoID":29022,"CourseChapterTopicPlaylistID":294413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.535","Text":"Hi, let\u0027s continue our discussion of the systems of gas exchange."},{"Start":"00:05.535 ","End":"00:10.350","Text":"In the previous video, we talked about surface area and how important that was."},{"Start":"00:10.350 ","End":"00:16.330","Text":"Now, let\u0027s look at the specialized systems that higher organisms have."},{"Start":"00:16.910 ","End":"00:21.420","Text":"There are gills that we discussed earlier and of course lungs,"},{"Start":"00:21.420 ","End":"00:26.505","Text":"but there\u0027s also skin can be an organ"},{"Start":"00:26.505 ","End":"00:32.130","Text":"through which oxygen and carbon dioxide diffuse."},{"Start":"00:32.130 ","End":"00:37.295","Text":"That\u0027s particularly the case in aquatic organisms that obtain oxygen from water,"},{"Start":"00:37.295 ","End":"00:41.180","Text":"where oxygen is lower concentration than in the atmosphere."},{"Start":"00:41.180 ","End":"00:43.385","Text":"We can see that, for instance,"},{"Start":"00:43.385 ","End":"00:48.545","Text":"in these organisms like frogs, for instance,"},{"Start":"00:48.545 ","End":"00:53.540","Text":"where there is some movement of oxygen"},{"Start":"00:53.540 ","End":"00:59.645","Text":"through the skin and they of course are amphibians."},{"Start":"00:59.645 ","End":"01:09.080","Text":"But earthworms will also do this thing and they\u0027ll use their skin as a respiratory organ."},{"Start":"01:09.080 ","End":"01:12.275","Text":"Of course, the respiratory surface must be kept"},{"Start":"01:12.275 ","End":"01:15.965","Text":"moist or wet so that the gases can diffuse"},{"Start":"01:15.965 ","End":"01:23.255","Text":"across the cell membranes if the earthworm dries out or if a toad dries out,"},{"Start":"01:23.255 ","End":"01:25.265","Text":"you know that it\u0027s even trouble."},{"Start":"01:25.265 ","End":"01:27.260","Text":"That\u0027s one of the reasons because of"},{"Start":"01:27.260 ","End":"01:33.830","Text":"this carbon dioxide oxygen exchange that occurs in the skin, of course,"},{"Start":"01:33.830 ","End":"01:35.810","Text":"in frogs also have lungs,"},{"Start":"01:35.810 ","End":"01:41.535","Text":"so it happens in different places across the skin,"},{"Start":"01:41.535 ","End":"01:43.760","Text":"the lungs and in fact in frogs,"},{"Start":"01:43.760 ","End":"01:46.850","Text":"it even occurs inside the mouth cavity."},{"Start":"01:46.850 ","End":"01:50.390","Text":"Sometimes you\u0027ll see frogs with their mouths open."},{"Start":"01:50.390 ","End":"01:53.495","Text":"Fish, of course, have gills,"},{"Start":"01:53.495 ","End":"01:55.635","Text":"but they\u0027re not the only organisms."},{"Start":"01:55.635 ","End":"01:57.620","Text":"Here\u0027s a salamander, for instance,"},{"Start":"01:57.620 ","End":"02:00.575","Text":"that has external gills."},{"Start":"02:00.575 ","End":"02:04.790","Text":"Aquatic organisms use these gills in the water,"},{"Start":"02:04.790 ","End":"02:06.230","Text":"passes by them,"},{"Start":"02:06.230 ","End":"02:08.300","Text":"and exchanges the gases."},{"Start":"02:08.300 ","End":"02:12.230","Text":"Then there\u0027s a very thin tissue filament and of course they are highly"},{"Start":"02:12.230 ","End":"02:17.495","Text":"branched and folded because we need to increase the surface area,"},{"Start":"02:17.495 ","End":"02:19.205","Text":"as we mentioned before."},{"Start":"02:19.205 ","End":"02:22.340","Text":"We can see some of these gill filaments in"},{"Start":"02:22.340 ","End":"02:28.625","Text":"this illustration that increases the surface area."},{"Start":"02:28.625 ","End":"02:31.140","Text":"Of course, inside the gills,"},{"Start":"02:31.140 ","End":"02:35.480","Text":"we have the blood which is moving through arteries and veins."},{"Start":"02:35.480 ","End":"02:42.140","Text":"these capillaries, which are going to bring the oxygenated blood to the tissues and"},{"Start":"02:42.140 ","End":"02:46.580","Text":"the waste carbon dioxide back from the tissues"},{"Start":"02:46.580 ","End":"02:51.165","Text":"so they can exchange that with the water outside."},{"Start":"02:51.165 ","End":"02:56.420","Text":"Here, you can see these capillaries that are inside the gills and they are"},{"Start":"02:56.420 ","End":"03:02.030","Text":"going to be bringing the gases in the 2 directions we mentioned."},{"Start":"03:02.030 ","End":"03:09.560","Text":"In fish, water will go in through the mouth and then out the gills and that are made,"},{"Start":"03:09.560 ","End":"03:11.525","Text":"as I said, of these filaments."},{"Start":"03:11.525 ","End":"03:14.270","Text":"They are further subdivided these filaments into"},{"Start":"03:14.270 ","End":"03:19.445","Text":"these little things called lamellae that increase the surface area."},{"Start":"03:19.445 ","End":"03:25.810","Text":"They\u0027re very thin and that ensures a minimal boundary between the blood and the water."},{"Start":"03:25.810 ","End":"03:30.080","Text":"As we mentioned, water goes in through the mouth over"},{"Start":"03:30.080 ","End":"03:35.570","Text":"the gills and then is ejected just behind the head."},{"Start":"03:35.570 ","End":"03:38.045","Text":"You can see that in fish,"},{"Start":"03:38.045 ","End":"03:40.039","Text":"most of us are familiar with that."},{"Start":"03:40.039 ","End":"03:43.370","Text":"Oxygen diffuses from the water to the blood,"},{"Start":"03:43.370 ","End":"03:49.845","Text":"and carbon dioxide diffuses in the opposite direction from the blood to the water."},{"Start":"03:49.845 ","End":"03:52.770","Text":"The blood and waterflow,"},{"Start":"03:52.770 ","End":"03:56.000","Text":"so the blood flowing through the gills and the water flowing"},{"Start":"03:56.000 ","End":"03:59.495","Text":"over them flow in counter current."},{"Start":"03:59.495 ","End":"04:02.525","Text":"That means they\u0027re going in opposite directions"},{"Start":"04:02.525 ","End":"04:05.930","Text":"and they flow past each other very quickly."},{"Start":"04:05.930 ","End":"04:09.020","Text":"Here\u0027s the waterflow and then we\u0027ve got the blood flow and"},{"Start":"04:09.020 ","End":"04:12.365","Text":"that increases the diffusion efficiency."},{"Start":"04:12.365 ","End":"04:16.950","Text":"Let\u0027s look at another system, that is insects."},{"Start":"04:16.950 ","End":"04:20.790","Text":"In insects, they have tracheal systems."},{"Start":"04:20.790 ","End":"04:25.033","Text":"In their case, they\u0027re circulatory systems,"},{"Start":"04:25.033 ","End":"04:26.450","Text":"in other words, their blood,"},{"Start":"04:26.450 ","End":"04:27.710","Text":"they don\u0027t really have blood, but they have"},{"Start":"04:27.710 ","End":"04:32.090","Text":"a circulatory system and the respiratory systems are separate."},{"Start":"04:32.090 ","End":"04:34.865","Text":"They\u0027re independent, unlike what we just saw"},{"Start":"04:34.865 ","End":"04:37.835","Text":"in fish or in lungs that we\u0027ll see in a minute."},{"Start":"04:37.835 ","End":"04:44.120","Text":"Blood there does not play a direct role in oxygen transport and instead,"},{"Start":"04:44.120 ","End":"04:49.955","Text":"there are these air-filled cavities or these tubes called trachea."},{"Start":"04:49.955 ","End":"04:51.920","Text":"So there\u0027s a tracheal system."},{"Start":"04:51.920 ","End":"04:57.350","Text":"There are these tubes that have small holes that open to the outside that are"},{"Start":"04:57.350 ","End":"05:04.215","Text":"called spiracles that are on the outside."},{"Start":"05:04.215 ","End":"05:07.115","Text":"These tubes then penetrate to every part of the body."},{"Start":"05:07.115 ","End":"05:11.690","Text":"There\u0027s a whole system of these tubes and at the extreme ends,"},{"Start":"05:11.690 ","End":"05:16.300","Text":"they have things good or called tracheoles."},{"Start":"05:16.300 ","End":"05:20.990","Text":"This allows oxygen to pass into the body directly and regulates the fusion"},{"Start":"05:20.990 ","End":"05:26.725","Text":"of water and so water vapor and carbon dioxide of course out."},{"Start":"05:26.725 ","End":"05:30.200","Text":"In order for this to become more efficient,"},{"Start":"05:30.200 ","End":"05:33.905","Text":"sometimes, it\u0027s required that the insects move."},{"Start":"05:33.905 ","End":"05:38.705","Text":"They ventilate the tracheal system by moving their body."},{"Start":"05:38.705 ","End":"05:40.025","Text":"In the next video,"},{"Start":"05:40.025 ","End":"05:45.080","Text":"we\u0027ll be discussing how this works in mammals,"},{"Start":"05:45.080 ","End":"05:49.199","Text":"and specifically, in us."}],"ID":30613},{"Watched":false,"Name":"Gas Exchange and theI mportance of Surface Area","Duration":"7m 44s","ChapterTopicVideoID":29023,"CourseChapterTopicPlaylistID":294413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.065","Text":"Hi, I\u0027m glad that you\u0027re back now."},{"Start":"00:04.065 ","End":"00:07.395","Text":"We\u0027re going to be discussing a new subject,"},{"Start":"00:07.395 ","End":"00:09.405","Text":"that is breathing really."},{"Start":"00:09.405 ","End":"00:12.750","Text":"Systems of gas exchange and as you\u0027ll see,"},{"Start":"00:12.750 ","End":"00:19.680","Text":"breathing or gas exchange is mainly oxygen in, carbon dioxide out."},{"Start":"00:19.680 ","End":"00:24.525","Text":"It doesn\u0027t really matter what the organism is as long as it\u0027s doing respiration,"},{"Start":"00:24.525 ","End":"00:26.670","Text":"that\u0027s what\u0027s going to be happening."},{"Start":"00:26.670 ","End":"00:30.765","Text":"Breathing actually is an involuntary event in"},{"Start":"00:30.765 ","End":"00:37.080","Text":"most higher organisms and it\u0027s regulated by the respiratory center in the brain."},{"Start":"00:37.080 ","End":"00:41.380","Text":"Well, let\u0027s look into this a bit more."},{"Start":"00:41.630 ","End":"00:44.540","Text":"Breathing has 2 parts to it."},{"Start":"00:44.540 ","End":"00:48.215","Text":"There\u0027s inhalation and that\u0027s when we,"},{"Start":"00:48.215 ","End":"00:51.905","Text":"in humans at least and mammals in general,"},{"Start":"00:51.905 ","End":"00:54.080","Text":"fill the lungs with oxygen,"},{"Start":"00:54.080 ","End":"00:56.615","Text":"which is absorbed and in the end of the day,"},{"Start":"00:56.615 ","End":"00:58.790","Text":"ATP is produced in the cells."},{"Start":"00:58.790 ","End":"01:01.220","Text":"Then we also have exhalation,"},{"Start":"01:01.220 ","End":"01:03.515","Text":"that is the air going out."},{"Start":"01:03.515 ","End":"01:06.245","Text":"As you can see here in exhalation,"},{"Start":"01:06.245 ","End":"01:12.680","Text":"the air rushes out and primarily takes carbon dioxide which leaves"},{"Start":"01:12.680 ","End":"01:19.095","Text":"the cells and it goes out of the body and the rest human,"},{"Start":"01:19.095 ","End":"01:21.845","Text":"as, if we\u0027re just lying at rest,"},{"Start":"01:21.845 ","End":"01:23.470","Text":"not doing much of anything,"},{"Start":"01:23.470 ","End":"01:27.140","Text":"we breathe about 15 times a minute on average."},{"Start":"01:27.140 ","End":"01:30.935","Text":"But different organisms and different mammals breathe at different rates."},{"Start":"01:30.935 ","End":"01:34.040","Text":"Dogs will breathe much more quickly,"},{"Start":"01:34.040 ","End":"01:36.575","Text":"about 15-30 times a minute."},{"Start":"01:36.575 ","End":"01:39.755","Text":"But in any case, both of us are really doing the same thing."},{"Start":"01:39.755 ","End":"01:45.365","Text":"We\u0027re inhaling and we\u0027re exhaling for the same reasons."},{"Start":"01:45.365 ","End":"01:48.505","Text":"What\u0027s happening with this gas exchange?"},{"Start":"01:48.505 ","End":"01:52.640","Text":"The functions are to deliver oxygen to the cells, as we said,"},{"Start":"01:52.640 ","End":"01:54.395","Text":"and remove carbon dioxide,"},{"Start":"01:54.395 ","End":"01:57.050","Text":"which is a waste product of respiration."},{"Start":"01:57.050 ","End":"01:58.715","Text":"In addition to that,"},{"Start":"01:58.715 ","End":"02:05.980","Text":"the pH of the blood is altered by how much carbon dioxide there is in it."},{"Start":"02:05.980 ","End":"02:10.090","Text":"It\u0027s altered by the change in carbon dioxide levels, and of course,"},{"Start":"02:10.090 ","End":"02:16.960","Text":"we want the pH of the blood to remain more or less the same as we live."},{"Start":"02:16.960 ","End":"02:20.410","Text":"An increase in carbon dioxide is going to increase"},{"Start":"02:20.410 ","End":"02:24.415","Text":"the carbonic acid that\u0027s dissolved in our blood,"},{"Start":"02:24.415 ","End":"02:26.965","Text":"therefore decreasing the pH."},{"Start":"02:26.965 ","End":"02:32.410","Text":"CO_2 up, pH going down more acidic."},{"Start":"02:32.410 ","End":"02:34.135","Text":"In addition, of course,"},{"Start":"02:34.135 ","End":"02:36.835","Text":"when we breathe, we talk."},{"Start":"02:36.835 ","End":"02:38.080","Text":"That\u0027s what I\u0027m doing now."},{"Start":"02:38.080 ","End":"02:39.760","Text":"Yes, and how does that work?"},{"Start":"02:39.760 ","End":"02:45.325","Text":"Well, air moves past our vocal folds or our vocal cords,"},{"Start":"02:45.325 ","End":"02:48.505","Text":"and that makes sounds and enables speech."},{"Start":"02:48.505 ","End":"02:54.515","Text":"Finally, we smell what\u0027s in the air and when we breathe in,"},{"Start":"02:54.515 ","End":"02:58.670","Text":"then we can smell airborne molecules that are"},{"Start":"02:58.670 ","End":"03:03.080","Text":"drawn into the nasal activity and that\u0027s called olfaction,"},{"Start":"03:03.080 ","End":"03:06.890","Text":"as we have mentioned in an earlier video."},{"Start":"03:06.890 ","End":"03:14.450","Text":"Now, the molecules of oxygen and carbon dioxide diffuse across membranes,"},{"Start":"03:14.450 ","End":"03:16.858","Text":"and to remind you what diffusion is,"},{"Start":"03:16.858 ","End":"03:21.140","Text":"diffusion is a passive movement of a substance from an area"},{"Start":"03:21.140 ","End":"03:25.700","Text":"of high concentration to an area of lower concentration,"},{"Start":"03:25.700 ","End":"03:27.050","Text":"and of course, therefore,"},{"Start":"03:27.050 ","End":"03:34.170","Text":"the rate of oxygen uptake must match its rate of diffusion across the membrane."},{"Start":"03:34.170 ","End":"03:37.790","Text":"The kinds of membranes that we\u0027re going to have and"},{"Start":"03:37.790 ","End":"03:42.550","Text":"the number of membranes that we\u0027re going to have is going to be very important."},{"Start":"03:42.550 ","End":"03:44.600","Text":"If a cell, therefore,"},{"Start":"03:44.600 ","End":"03:49.205","Text":"is exceptionally large or if it\u0027s very thick,"},{"Start":"03:49.205 ","End":"03:51.200","Text":"then diffusion will not be able to provide"},{"Start":"03:51.200 ","End":"03:57.085","Text":"sufficient oxygen for its respiration to get inside."},{"Start":"03:57.085 ","End":"04:04.625","Text":"The dependence on diffusion is feasible only for very small,"},{"Start":"04:04.625 ","End":"04:07.970","Text":"as we\u0027ll see, or highly flattened organisms."},{"Start":"04:07.970 ","End":"04:13.005","Text":"Some organisms like these flatworms that we see are very flat,"},{"Start":"04:13.005 ","End":"04:20.180","Text":"so their surface area is very large as compared with their volume and that allows them in"},{"Start":"04:20.180 ","End":"04:24.245","Text":"the water to diffuse materials in and out at"},{"Start":"04:24.245 ","End":"04:29.570","Text":"a sufficient speed so that their cells can live."},{"Start":"04:29.570 ","End":"04:34.415","Text":"But that\u0027s not the case for much bigger and thicker organisms like"},{"Start":"04:34.415 ","End":"04:40.150","Text":"us that have lungs to facilitate things and we\u0027ll see how that works."},{"Start":"04:40.150 ","End":"04:43.400","Text":"Organisms have devised different means"},{"Start":"04:43.400 ","End":"04:46.144","Text":"of obtaining oxygen from the surrounding atmosphere."},{"Start":"04:46.144 ","End":"04:47.995","Text":"Of course, we mentioned before,"},{"Start":"04:47.995 ","End":"04:53.830","Text":"just a couple of minutes ago that the surface area is very important,"},{"Start":"04:53.830 ","End":"04:55.245","Text":"and of course,"},{"Start":"04:55.245 ","End":"04:59.720","Text":"as the animal size increases,"},{"Start":"04:59.720 ","End":"05:03.350","Text":"then the diffusion must increase as well."},{"Start":"05:03.350 ","End":"05:10.130","Text":"The diffusion distances increase and the ratio of surface area to volume drops naturally"},{"Start":"05:10.130 ","End":"05:17.160","Text":"unless there\u0027s some specialized organ like the lungs that we\u0027ll see in a minute."},{"Start":"05:17.160 ","End":"05:19.190","Text":"Just to see how much that happens,"},{"Start":"05:19.190 ","End":"05:21.935","Text":"if we have a 1 centimeter cube,"},{"Start":"05:21.935 ","End":"05:26.720","Text":"then the surface-to-volume ratio will be 6:1."},{"Start":"05:26.720 ","End":"05:29.945","Text":"However, if we raise the size,"},{"Start":"05:29.945 ","End":"05:32.405","Text":"let\u0027s go to the 3 centimeter cube,"},{"Start":"05:32.405 ","End":"05:36.285","Text":"then the surface area to volume is only 2:1."},{"Start":"05:36.285 ","End":"05:39.290","Text":"You can see what the calculations are over here."},{"Start":"05:39.290 ","End":"05:44.165","Text":"That\u0027s the surface area to volume drops."},{"Start":"05:44.165 ","End":"05:49.310","Text":"In unicellular organisms, diffusion across the cell membrane"},{"Start":"05:49.310 ","End":"05:54.440","Text":"is sufficient because they\u0027re very small for supplying oxygen to the cell."},{"Start":"05:54.440 ","End":"05:59.150","Text":"However, in larger organisms that\u0027s going to be a problem."},{"Start":"05:59.150 ","End":"06:00.590","Text":"In this figure,"},{"Start":"06:00.590 ","End":"06:02.705","Text":"you can see a budding yeast."},{"Start":"06:02.705 ","End":"06:09.075","Text":"This is the yeast that we have in bread, baking yeast,"},{"Start":"06:09.075 ","End":"06:14.075","Text":"or in wine or in beer and in these small organisms,"},{"Start":"06:14.075 ","End":"06:17.965","Text":"diffusion is sufficient to meet their needs."},{"Start":"06:17.965 ","End":"06:20.675","Text":"However, let\u0027s say in fish,"},{"Start":"06:20.675 ","End":"06:21.995","Text":"which are much bigger,"},{"Start":"06:21.995 ","End":"06:23.930","Text":"they need a specialized organ."},{"Start":"06:23.930 ","End":"06:26.645","Text":"We have lungs, they have gills."},{"Start":"06:26.645 ","End":"06:28.100","Text":"That\u0027s what we see here."},{"Start":"06:28.100 ","End":"06:34.710","Text":"Yes, and the respiratory passage is accompanied by a circulatory system."},{"Start":"06:34.710 ","End":"06:36.170","Text":"Here you can see the blood actually,"},{"Start":"06:36.170 ","End":"06:38.375","Text":"that\u0027s why it\u0027s red going through the gills,"},{"Start":"06:38.375 ","End":"06:44.830","Text":"which is going to deliver the oxygen to other parts of the body."},{"Start":"06:44.830 ","End":"06:48.950","Text":"How does the oxygen get in to these systems?"},{"Start":"06:48.950 ","End":"06:55.175","Text":"Well, it does that by diffusion as we mentioned and there\u0027s a gas exchange by diffusion,"},{"Start":"06:55.175 ","End":"06:58.970","Text":"that works well, as we said,"},{"Start":"06:58.970 ","End":"07:03.650","Text":"for small organisms like a millimeter in diameter and there are"},{"Start":"07:03.650 ","End":"07:11.090","Text":"some organisms like flatworms that we mentioned before and these cnidarians,"},{"Start":"07:11.090 ","End":"07:13.460","Text":"like jellyfish for instance,"},{"Start":"07:13.460 ","End":"07:18.650","Text":"where every cell in them is close the exterior environment and therefore,"},{"Start":"07:18.650 ","End":"07:22.310","Text":"we have a large surface area for diffusion"},{"Start":"07:22.310 ","End":"07:27.640","Text":"and access to oxygen and removal of carbon dioxide."},{"Start":"07:27.640 ","End":"07:34.790","Text":"That\u0027s in the flatworms and for use as an example, as we mentioned,"},{"Start":"07:34.790 ","End":"07:36.019","Text":"if they were cylindrical,"},{"Start":"07:36.019 ","End":"07:42.790","Text":"then the cells in the center would not be able to get oxygen and that\u0027s why they\u0027re flat."}],"ID":30614},{"Watched":false,"Name":"The Trachea and Lungs","Duration":"6m 22s","ChapterTopicVideoID":29024,"CourseChapterTopicPlaylistID":294413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.045","Text":"Now, let\u0027s continue our discussion of gas exchange and move on to mammals."},{"Start":"00:06.045 ","End":"00:08.235","Text":"In mammalian systems, of course,"},{"Start":"00:08.235 ","End":"00:13.710","Text":"we have lungs but the air has to get in to the body."},{"Start":"00:13.710 ","End":"00:19.500","Text":"The air gets in through a nasal cavity that\u0027s behind our nose,"},{"Start":"00:19.500 ","End":"00:23.925","Text":"that we have a big area in there that is found just inside the nose."},{"Start":"00:23.925 ","End":"00:26.130","Text":"Now, what\u0027s the function of this nasal cavity?"},{"Start":"00:26.130 ","End":"00:29.295","Text":"Well, it warms the air to body temperature."},{"Start":"00:29.295 ","End":"00:31.680","Text":"We don\u0027t want the air to be too cold and that\u0027s"},{"Start":"00:31.680 ","End":"00:34.200","Text":"uncomfortable we know that and also it humidifiers"},{"Start":"00:34.200 ","End":"00:36.090","Text":"it because the air needs to be"},{"Start":"00:36.090 ","End":"00:39.599","Text":"humid so that we don\u0027t lose too much water while we\u0027re breathing."},{"Start":"00:39.599 ","End":"00:42.820","Text":"Water of course is very important."},{"Start":"00:42.820 ","End":"00:46.565","Text":"The air then is equilibrated to body conditions and"},{"Start":"00:46.565 ","End":"00:50.990","Text":"that reduces damage that cold or dry air can cause."},{"Start":"00:50.990 ","End":"00:53.285","Text":"At the same time,"},{"Start":"00:53.285 ","End":"00:58.530","Text":"we want to filter out particles that might be bothering our lungs,"},{"Start":"00:58.530 ","End":"01:01.460","Text":"so particulate matter that\u0027s floating the air is also"},{"Start":"01:01.460 ","End":"01:04.490","Text":"removed and we\u0027ve got mucus and cilia,"},{"Start":"01:04.490 ","End":"01:12.485","Text":"these very small little hairs that remove the particulates in our breathing system."},{"Start":"01:12.485 ","End":"01:14.210","Text":"In the naval cavity, of course,"},{"Start":"01:14.210 ","End":"01:20.510","Text":"air passes through this area called the pharynx and the larynx,"},{"Start":"01:20.510 ","End":"01:25.760","Text":"that\u0027s our voice box as it makes its way down into"},{"Start":"01:25.760 ","End":"01:32.440","Text":"the trachea that\u0027s the tube through which air passes going to the lung."},{"Start":"01:32.440 ","End":"01:35.735","Text":"Now let\u0027s look at the trachea in more detail."},{"Start":"01:35.735 ","End":"01:43.530","Text":"The trachea as it comes down from our larynx funnels air in and out of the body."},{"Start":"01:43.530 ","End":"01:49.470","Text":"Of course we have air going in and we have air going out."},{"Start":"01:49.470 ","End":"01:51.345","Text":"The human trachea,"},{"Start":"01:51.345 ","End":"01:55.050","Text":"this trachea is about 10-12 centimeters long,"},{"Start":"01:55.050 ","End":"02:01.420","Text":"2 centimeters in diameter and we have the esophagus which sits just behind it."},{"Start":"02:01.420 ","End":"02:05.060","Text":"It extends from the larynx into the chest cavity"},{"Start":"02:05.060 ","End":"02:09.290","Text":"that\u0027s just below of course and it\u0027s there."},{"Start":"02:09.290 ","End":"02:13.370","Text":"There, it divides into 2 primary branches or"},{"Start":"02:13.370 ","End":"02:20.270","Text":"bronchi in the mid thorax and it\u0027s made up of these rings,"},{"Start":"02:20.270 ","End":"02:23.225","Text":"they\u0027re incomplete because they don\u0027t go all the way around"},{"Start":"02:23.225 ","End":"02:26.930","Text":"of hyaline cartilage and smooth muscle."},{"Start":"02:26.930 ","End":"02:34.010","Text":"We have both muscle and cartilage it\u0027s a flexible situation there."},{"Start":"02:34.010 ","End":"02:40.490","Text":"Now, inside the respiratory tract we have different cell types."},{"Start":"02:40.490 ","End":"02:45.725","Text":"We\u0027ve got goblet cells that are specialized for synthesis and secretion of mucus."},{"Start":"02:45.725 ","End":"02:49.640","Text":"Remember we mentioned that the mucus is important for capturing"},{"Start":"02:49.640 ","End":"02:54.685","Text":"little particles and also for keeping things humid."},{"Start":"02:54.685 ","End":"03:02.180","Text":"We\u0027ve got these goblet cells over here that are producing this gel or this liquid"},{"Start":"03:02.180 ","End":"03:04.480","Text":"that\u0027s out there and we also have"},{"Start":"03:04.480 ","End":"03:09.650","Text":"these ciliated epithelia with these little cilia, these little hairs."},{"Start":"03:09.650 ","End":"03:16.655","Text":"Those hairs then can propel the particles that are caught back up towards the pharynx."},{"Start":"03:16.655 ","End":"03:21.710","Text":"In addition to that of course we have some cartilage and that makes it strong,"},{"Start":"03:21.710 ","End":"03:27.425","Text":"so provides strength and the trachea is supported so that the passage stays open."},{"Start":"03:27.425 ","End":"03:32.765","Text":"In addition, remember we said that to the cartilage we have smooth muscle."},{"Start":"03:32.765 ","End":"03:39.830","Text":"The smooth muscle contraction can change the trachea\u0027s diameter like I just"},{"Start":"03:39.830 ","End":"03:43.430","Text":"did and that causes expired air"},{"Start":"03:43.430 ","End":"03:47.147","Text":"to rush at greater force so that we can clear our throats,"},{"Start":"03:47.147 ","End":"03:50.195","Text":"for instance, when we\u0027re coughing."},{"Start":"03:50.195 ","End":"03:54.245","Text":"Let\u0027s look a little bit further down now and look"},{"Start":"03:54.245 ","End":"03:59.430","Text":"into the lungs in more detail into the lungs here."},{"Start":"03:59.430 ","End":"04:01.339","Text":"At the end of the trachea,"},{"Start":"04:01.339 ","End":"04:03.980","Text":"we can have more splitting."},{"Start":"04:03.980 ","End":"04:06.223","Text":"We\u0027ve got the right and left lungs,"},{"Start":"04:06.223 ","End":"04:11.190","Text":"the right lung actually can be divided into 3 different lobes."},{"Start":"04:11.190 ","End":"04:13.680","Text":"The left lung only 2 lobes."},{"Start":"04:13.680 ","End":"04:16.043","Text":"The right lung is a bit larger,"},{"Start":"04:16.043 ","End":"04:17.990","Text":"the left lung is a bit smaller."},{"Start":"04:17.990 ","End":"04:21.425","Text":"We\u0027ve got the heart there which is going to be in the way."},{"Start":"04:21.425 ","End":"04:24.015","Text":"At the bottom of the lungs,"},{"Start":"04:24.015 ","End":"04:27.665","Text":"we\u0027ve got a large muscle called the diaphragm."},{"Start":"04:27.665 ","End":"04:35.200","Text":"That\u0027s what\u0027s going to be pushing our lungs up and down and allowing the breathing."},{"Start":"04:35.200 ","End":"04:40.790","Text":"But if we continue looking further down the bronchi,"},{"Start":"04:40.790 ","End":"04:44.960","Text":"we see that they split even further."},{"Start":"04:44.960 ","End":"04:50.390","Text":"We have secondary, tertiary branching and each of"},{"Start":"04:50.390 ","End":"04:54.020","Text":"this secondary and tertiary bronchi"},{"Start":"04:54.020 ","End":"04:58.970","Text":"eventually go into what are called terminal bronchioles."},{"Start":"04:58.970 ","End":"05:05.689","Text":"Terminal bronchioles at the very end and they actually even split further."},{"Start":"05:05.689 ","End":"05:07.370","Text":"They subdivide now into"},{"Start":"05:07.370 ","End":"05:13.430","Text":"microscopic respiratory bronchioles and that\u0027s where we\u0027re going to start"},{"Start":"05:13.430 ","End":"05:21.640","Text":"having the gas exchange in these areas that are called alveoli."},{"Start":"05:21.640 ","End":"05:24.830","Text":"The terminal bronchioles mark the end of"},{"Start":"05:24.830 ","End":"05:29.420","Text":"the conducting zone where the air is moving through and"},{"Start":"05:29.420 ","End":"05:32.825","Text":"they begin the area of the respiratory zone"},{"Start":"05:32.825 ","End":"05:37.625","Text":"where the exchange of materials is going to be half."},{"Start":"05:37.625 ","End":"05:42.680","Text":"The cartilage in these at the end of the bronchial tubes is replaced by"},{"Start":"05:42.680 ","End":"05:48.935","Text":"these elastic fibers that are going to allow expansion and contraction of the system."},{"Start":"05:48.935 ","End":"05:53.135","Text":"The bronchi are innervated by"},{"Start":"05:53.135 ","End":"06:00.150","Text":"both autonomous nervous systems so that we can breathe out thinking,"},{"Start":"06:00.150 ","End":"06:01.745","Text":"yes, we have"},{"Start":"06:01.745 ","End":"06:07.940","Text":"a parasympathetic control contraction and a sympathetic control relaxation,"},{"Start":"06:07.940 ","End":"06:13.400","Text":"that\u0027s the breathing in and out of the muscle and the bronchi and the bronchioles."},{"Start":"06:13.400 ","End":"06:20.880","Text":"We have this relaxation and contraction in addition to the diaphragm moving up and down."}],"ID":30615},{"Watched":false,"Name":"The Fine Structure of the Lungs","Duration":"6m 12s","ChapterTopicVideoID":29025,"CourseChapterTopicPlaylistID":294413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.200","Text":"In this final video of this section,"},{"Start":"00:04.200 ","End":"00:08.970","Text":"we\u0027re going to continue our discussion looking at the alveoli."},{"Start":"00:08.970 ","End":"00:12.900","Text":"In humans, the respiratory bronchioles,"},{"Start":"00:12.900 ","End":"00:21.090","Text":"these last bronchi before the alveoli are smaller,"},{"Start":"00:21.090 ","End":"00:24.660","Text":"the diameter of them is smaller than half a millimeter."},{"Start":"00:24.660 ","End":"00:26.520","Text":"That\u0027s very small,"},{"Start":"00:26.520 ","End":"00:34.630","Text":"and they lack cartilage and they rely on the air that\u0027s inhaled to support their shape."},{"Start":"00:34.630 ","End":"00:40.775","Text":"They don\u0027t collapse because of the air that\u0027s inside and the respiratory bronchioles,"},{"Start":"00:40.775 ","End":"00:44.555","Text":"further subdivide into these alveolar ducts,"},{"Start":"00:44.555 ","End":"00:49.760","Text":"and they\u0027re surrounded by many alveoli and what are called"},{"Start":"00:49.760 ","End":"00:57.050","Text":"alveolar sacs or a whole bunch of alveoli together will be called an alveolar sac."},{"Start":"00:57.050 ","End":"01:01.700","Text":"They resemble bunches of grapes if you look at them and they\u0027re tethered,"},{"Start":"01:01.700 ","End":"01:06.555","Text":"they\u0027re connected to the end of the bronchioles."},{"Start":"01:06.555 ","End":"01:14.535","Text":"Let\u0027s now look even further inside at one of these alveoli."},{"Start":"01:14.535 ","End":"01:19.280","Text":"What we see is that surrounding the alveoli,"},{"Start":"01:19.280 ","End":"01:21.170","Text":"we have, of course,"},{"Start":"01:21.170 ","End":"01:31.235","Text":"the blood system moving through capillaries in this what\u0027s called the acinar region."},{"Start":"01:31.235 ","End":"01:34.610","Text":"The alveoli ducts are attached to the end of"},{"Start":"01:34.610 ","End":"01:39.215","Text":"every bronchial and they\u0027re about a 100 of them,"},{"Start":"01:39.215 ","End":"01:43.700","Text":"each of them containing between 20 and 30 alveoli"},{"Start":"01:43.700 ","End":"01:49.010","Text":"that are now about 200 to 300 microns in diameter."},{"Start":"01:49.010 ","End":"01:54.530","Text":"We\u0027re getting much smaller so that the gas exchange can occur."},{"Start":"01:54.530 ","End":"01:58.550","Text":"This occurs only in the alveoli and they are made up of"},{"Start":"01:58.550 ","End":"02:05.070","Text":"these thin-walled cells that are called parenchymal cells."},{"Start":"02:05.070 ","End":"02:10.700","Text":"They\u0027re typically only 1 cell thick so that there can be"},{"Start":"02:10.700 ","End":"02:17.700","Text":"a good exchange of the oxygen going into the blood and the carbon dioxide coming out."},{"Start":"02:17.700 ","End":"02:21.975","Text":"They are in direct contact with the capillaries,"},{"Start":"02:21.975 ","End":"02:28.430","Text":"the alveoli have the direct contact with the capillaries of the circulatory system."},{"Start":"02:28.430 ","End":"02:32.600","Text":"The capillaries themselves are only 1 cell thick."},{"Start":"02:32.600 ","End":"02:34.190","Text":"This whole thing, of course,"},{"Start":"02:34.190 ","End":"02:36.515","Text":"is very fragile,"},{"Start":"02:36.515 ","End":"02:40.880","Text":"and this ensures that oxygen will diffuse from the alveoli into the blood"},{"Start":"02:40.880 ","End":"02:46.545","Text":"and carbon dioxide out when we exhale."},{"Start":"02:46.545 ","End":"02:50.415","Text":"Now, let\u0027s look at the general anatomy,"},{"Start":"02:50.415 ","End":"02:55.440","Text":"and we see the 2 branches of the trachea,"},{"Start":"02:55.440 ","End":"02:58.510","Text":"and what we see is that there is"},{"Start":"02:58.510 ","End":"03:01.230","Text":"this further subdivision and further subdivision, and further subdivision,"},{"Start":"03:01.230 ","End":"03:07.360","Text":"and here we can have a see a microscopic image where"},{"Start":"03:07.360 ","End":"03:12.235","Text":"the arrangement emphasizes the structural and functional relationship"},{"Start":"03:12.235 ","End":"03:14.665","Text":"of the respiratory and circulatory systems."},{"Start":"03:14.665 ","End":"03:18.290","Text":"We\u0027ve got a huge number alveoli,"},{"Start":"03:18.290 ","End":"03:22.300","Text":"of course, in order to increase the surface area."},{"Start":"03:22.300 ","End":"03:26.470","Text":"We\u0027ve got about 300 million in each lung."},{"Start":"03:26.470 ","End":"03:28.040","Text":"Of course, that makes"},{"Start":"03:28.040 ","End":"03:33.844","Text":"a very sponge-like consistency and that makes the surface area enormous,"},{"Start":"03:33.844 ","End":"03:37.515","Text":"about 75 square meters."},{"Start":"03:37.515 ","End":"03:41.570","Text":"This allows for a very efficient gas exchange."},{"Start":"03:41.570 ","End":"03:46.039","Text":"Combined with a thin-walled nature of the alveolar cells,"},{"Start":"03:46.039 ","End":"03:52.040","Text":"these parenchymal cells, gases can easily diffuse across the cells."},{"Start":"03:52.040 ","End":"03:54.170","Text":"Now, in addition to that, of course,"},{"Start":"03:54.170 ","End":"03:57.530","Text":"we\u0027ve got some protective systems in order to keep particles out,"},{"Start":"03:57.530 ","End":"04:00.154","Text":"as we mentioned before, if we look into the nose,"},{"Start":"04:00.154 ","End":"04:03.395","Text":"we can see that there are hairs that are visible and they\u0027re"},{"Start":"04:03.395 ","End":"04:08.810","Text":"smaller cilia that are not in order to keep dust, viral particles,"},{"Start":"04:08.810 ","End":"04:13.040","Text":"bacteria, and all things out so that we don\u0027t get infections in"},{"Start":"04:13.040 ","End":"04:17.660","Text":"our lungs and so that we don\u0027t have an allergic or immune response."},{"Start":"04:17.660 ","End":"04:21.920","Text":"The nasal cavity has these hairs that we can see and the"},{"Start":"04:21.920 ","End":"04:27.050","Text":"mucus that traps the small molecules and prevents their entry into the lungs."},{"Start":"04:27.050 ","End":"04:30.650","Text":"The lungs themselves also have mucus."},{"Start":"04:30.650 ","End":"04:35.570","Text":"This mucus is a complex glycoprotein in addition"},{"Start":"04:35.570 ","End":"04:40.075","Text":"to the water with salts that traps the particulates,"},{"Start":"04:40.075 ","End":"04:46.930","Text":"and they\u0027re the cilia that move any particulates that are trapped back out,"},{"Start":"04:46.930 ","End":"04:49.725","Text":"as we\u0027ve mentioned earlier."},{"Start":"04:49.725 ","End":"04:58.685","Text":"The cilia move, they beat actually together in unison and move mucus and particles"},{"Start":"04:58.685 ","End":"05:02.900","Text":"out of the bronchi and the bronchioles back up into the throat"},{"Start":"05:02.900 ","End":"05:07.444","Text":"where they\u0027re either swallowed or they can be coughed out sometimes."},{"Start":"05:07.444 ","End":"05:10.325","Text":"But even if they\u0027re swallowed into the esophagus,"},{"Start":"05:10.325 ","End":"05:13.130","Text":"they\u0027re gone, and that\u0027s important."},{"Start":"05:13.130 ","End":"05:17.525","Text":"Lastly, let\u0027s look at what happens when someone"},{"Start":"05:17.525 ","End":"05:22.600","Text":"smokes and is intentionally putting particles into their lungs."},{"Start":"05:22.600 ","End":"05:25.880","Text":"Here you can see a smoker\u0027s lung and what it looks like."},{"Start":"05:25.880 ","End":"05:29.420","Text":"Tar and other substances get into the lung through"},{"Start":"05:29.420 ","End":"05:33.340","Text":"cigarette smoke and they destroy or paralyze the cilia,"},{"Start":"05:33.340 ","End":"05:35.340","Text":"so you hear people coughing hard,"},{"Start":"05:35.340 ","End":"05:39.740","Text":"it\u0027s very hard for them to breathe well if they\u0027re heavy smokers,"},{"Start":"05:39.740 ","End":"05:44.000","Text":"and that makes them removal of particles much more difficult."},{"Start":"05:44.000 ","End":"05:48.560","Text":"Smoking also causes the lungs to produce even more mucus."},{"Start":"05:48.560 ","End":"05:54.260","Text":"That\u0027s all that coughing and the damaged cilia are not able to move well."},{"Start":"05:54.260 ","End":"05:58.640","Text":"That\u0027s that persistent cough that you hear as the lungs try to"},{"Start":"05:58.640 ","End":"06:02.750","Text":"rid themselves of particulate matter and makes smokers,"},{"Start":"06:02.750 ","End":"06:08.030","Text":"therefore, also more susceptible to various respiratory ailments."},{"Start":"06:08.030 ","End":"06:11.280","Text":"I don\u0027t suggest that you smoke."}],"ID":30616}],"Thumbnail":null,"ID":294413},{"Name":"Gas Exchange across Respiratory Surfaces","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Lung Diseases and Gas Partial Pressures","Duration":"6m 31s","ChapterTopicVideoID":29029,"CourseChapterTopicPlaylistID":294414,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.355","Text":"In the previous video,"},{"Start":"00:02.355 ","End":"00:07.500","Text":"we talked about various lung volumes and their capacities,"},{"Start":"00:07.500 ","End":"00:10.995","Text":"the definitions for people who are breathing normally,"},{"Start":"00:10.995 ","End":"00:13.425","Text":"who have no problems in their lungs."},{"Start":"00:13.425 ","End":"00:15.045","Text":"But as you know,"},{"Start":"00:15.045 ","End":"00:18.990","Text":"there are some people who don\u0027t breathe normally."},{"Start":"00:18.990 ","End":"00:20.040","Text":"They may have asthma,"},{"Start":"00:20.040 ","End":"00:22.100","Text":"they may have other respiratory problems,"},{"Start":"00:22.100 ","End":"00:25.529","Text":"they may get older and not breathe as well."},{"Start":"00:25.529 ","End":"00:32.100","Text":"In medicine, there are ways of measuring various lung capacities,"},{"Start":"00:32.100 ","End":"00:35.265","Text":"and this is called spirometry."},{"Start":"00:35.265 ","End":"00:40.310","Text":"This is the most common type of pulmonary function or breathing test."},{"Start":"00:40.310 ","End":"00:41.720","Text":"What does it measure?"},{"Start":"00:41.720 ","End":"00:46.260","Text":"It measures something called the forced expiratory volume."},{"Start":"00:46.260 ","End":"00:50.495","Text":"That\u0027s how much air can be forced out of the lung over a specific period."},{"Start":"00:50.495 ","End":"00:53.285","Text":"Notice there\u0027s a time scale here."},{"Start":"00:53.285 ","End":"00:59.665","Text":"Usually, it\u0027s about 1 second and that can be denoted as FEV1."},{"Start":"00:59.665 ","End":"01:02.720","Text":"How does this work? A patient takes a deep breath and"},{"Start":"01:02.720 ","End":"01:05.555","Text":"then blows as hard as possible into a tube,"},{"Start":"01:05.555 ","End":"01:09.935","Text":"and then the machine and the technician monitors how"},{"Start":"01:09.935 ","End":"01:14.835","Text":"quickly the air is excursed as it comes out."},{"Start":"01:14.835 ","End":"01:22.505","Text":"The forced vital capacity,"},{"Start":"01:22.505 ","End":"01:27.230","Text":"this would be the total amount of air that can be forcibly exhaled."},{"Start":"01:27.230 ","End":"01:29.000","Text":"How much totally can you do it?"},{"Start":"01:29.000 ","End":"01:31.780","Text":"That\u0027s not a function of time."},{"Start":"01:31.780 ","End":"01:37.820","Text":"Now, the ratio of these 2 values is used to diagnose lung diseases such as asthma,"},{"Start":"01:37.820 ","End":"01:40.580","Text":"emphysema, fibrosis, and things of that sort."},{"Start":"01:40.580 ","End":"01:44.940","Text":"Normally, the FEV1 in 1 second,"},{"Start":"01:44.940 ","End":"01:49.160","Text":"so how much you can breathe out in 1 second to the total amount that you"},{"Start":"01:49.160 ","End":"01:54.455","Text":"can breathe out is about 0.7 or greater."},{"Start":"01:54.455 ","End":"01:56.105","Text":"If it\u0027s lower than that,"},{"Start":"01:56.105 ","End":"01:58.680","Text":"then the lungs are not compliant."},{"Start":"01:58.680 ","End":"02:00.330","Text":"That means they don\u0027t move very quickly,"},{"Start":"02:00.330 ","End":"02:03.150","Text":"they might be stiff and they can\u0027t bend properly,"},{"Start":"02:03.150 ","End":"02:11.060","Text":"and that would be a characteristic of some problem like asthma for instance."},{"Start":"02:11.060 ","End":"02:20.120","Text":"Now, we will continue our discussion now discussing the properties of gases which will"},{"Start":"02:20.120 ","End":"02:24.530","Text":"help explain to us why it is that oxygen moves"},{"Start":"02:24.530 ","End":"02:29.765","Text":"in 1 direction whereas carbon dioxide moves in the other direction."},{"Start":"02:29.765 ","End":"02:33.500","Text":"You remember we discussed partial pressures."},{"Start":"02:33.500 ","End":"02:40.740","Text":"We know for instance that air is composed of different molecules."},{"Start":"02:40.740 ","End":"02:47.705","Text":"In fact, about 78.6 percent of normal air that we breathe on Earth,"},{"Start":"02:47.705 ","End":"02:50.875","Text":"say 78 percent something like that,"},{"Start":"02:50.875 ","End":"02:53.600","Text":"is actually nitrogen, not oxygen,"},{"Start":"02:53.600 ","End":"02:54.920","Text":"and not carbon dioxide."},{"Start":"02:54.920 ","End":"02:59.035","Text":"Oxygen makes up about 21 percent or so,"},{"Start":"02:59.035 ","End":"03:02.610","Text":"20.9 in this figure,"},{"Start":"03:02.610 ","End":"03:06.975","Text":"and water makes up roughly half a percent."},{"Start":"03:06.975 ","End":"03:11.830","Text":"There\u0027s water vapor, it depends of course on the relative humidity."},{"Start":"03:11.830 ","End":"03:14.450","Text":"How much water there will be in the air."},{"Start":"03:14.450 ","End":"03:16.850","Text":"You can be in a dry climate or in a wet climate."},{"Start":"03:16.850 ","End":"03:24.560","Text":"But there is a little bit of water that is water vapor that\u0027s in the air and of course,"},{"Start":"03:24.560 ","End":"03:29.195","Text":"there is carbon dioxide which is a very low amount."},{"Start":"03:29.195 ","End":"03:32.720","Text":"Notice the oxygen is about 21 percent,"},{"Start":"03:32.720 ","End":"03:38.314","Text":"whereas the carbon dioxide is 0.04 percent."},{"Start":"03:38.314 ","End":"03:40.600","Text":"Much, much less."},{"Start":"03:40.600 ","End":"03:46.745","Text":"So there is going to be a partial pressure of each of these things,"},{"Start":"03:46.745 ","End":"03:50.360","Text":"as we discussed previously in the different video."},{"Start":"03:50.360 ","End":"03:55.100","Text":"The partial pressure of the oxygen, the nitrogen,"},{"Start":"03:55.100 ","End":"04:03.440","Text":"is the nitrogen-oxygen in water and carbon dioxide together with"},{"Start":"04:03.440 ","End":"04:08.135","Text":"a few other gases that are not shown in this figure"},{"Start":"04:08.135 ","End":"04:13.445","Text":"are going to make up a total pressure."},{"Start":"04:13.445 ","End":"04:18.635","Text":"The pressure is made up of these partial pressures."},{"Start":"04:18.635 ","End":"04:28.370","Text":"The partial pressure of each of them is going to be the total atmospheric pressure,"},{"Start":"04:28.370 ","End":"04:32.120","Text":"the total pressure that we have that changes a little bit depending"},{"Start":"04:32.120 ","End":"04:36.380","Text":"on the elevation we\u0027re at and what the weather is outside,"},{"Start":"04:36.380 ","End":"04:40.430","Text":"but the percentage of the mixture of"},{"Start":"04:40.430 ","End":"04:46.025","Text":"a particular gas is going to be the partial pressure for each of them."},{"Start":"04:46.025 ","End":"04:50.705","Text":"In this case, we talked about 4 different molecules;"},{"Start":"04:50.705 ","End":"04:55.115","Text":"nitrogen, oxygen, water, and carbon dioxide."},{"Start":"04:55.115 ","End":"05:00.320","Text":"Those together are going to make up atmospheric pressure,"},{"Start":"05:00.320 ","End":"05:04.340","Text":"which is measured in millimeters of mercury."},{"Start":"05:04.340 ","End":"05:06.350","Text":"Typically at sea level,"},{"Start":"05:06.350 ","End":"05:09.530","Text":"that\u0027s 760 millimeters of mercury."},{"Start":"05:09.530 ","End":"05:18.960","Text":"That\u0027s how high mercury can be pushed by the total gas pressure."},{"Start":"05:18.960 ","End":"05:23.795","Text":"That\u0027s how gas pressure is measured in millimeters of mercury."},{"Start":"05:23.795 ","End":"05:28.490","Text":"The partial pressure for instance of oxygen would be"},{"Start":"05:28.490 ","End":"05:33.800","Text":"the 21 percent of the 760 millimeters,"},{"Start":"05:33.800 ","End":"05:37.310","Text":"which would be a 160 millimeters of mercury."},{"Start":"05:37.310 ","End":"05:43.895","Text":"In nitrogen, it would be 78 percent of the 760,"},{"Start":"05:43.895 ","End":"05:48.255","Text":"which is about 593 millimeters of mercury."},{"Start":"05:48.255 ","End":"05:51.060","Text":"This is important for us to understand as you\u0027ll"},{"Start":"05:51.060 ","End":"05:53.870","Text":"see because it\u0027s going to help us understand"},{"Start":"05:53.870 ","End":"05:58.205","Text":"the different partial pressures that are in the bloodstream"},{"Start":"05:58.205 ","End":"06:03.155","Text":"and that are in the lungs will help explain,"},{"Start":"06:03.155 ","End":"06:09.385","Text":"again, how oxygen moves in 1 direction and carbon dioxide in the other."},{"Start":"06:09.385 ","End":"06:12.380","Text":"Note, that at high altitudes,"},{"Start":"06:12.380 ","End":"06:15.800","Text":"the total atmospheric pressure is going to decrease,"},{"Start":"06:15.800 ","End":"06:17.710","Text":"but the concentrations don\u0027t."},{"Start":"06:17.710 ","End":"06:24.035","Text":"So the partial pressures are going to be as a percentage will remain the same,"},{"Start":"06:24.035 ","End":"06:28.770","Text":"the absolute numbers will change."}],"ID":30608},{"Watched":false,"Name":"Lungs and Gas Exchange","Duration":"6m 1s","ChapterTopicVideoID":29030,"CourseChapterTopicPlaylistID":294414,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.480","Text":"I\u0027m glad you\u0027re back to discuss"},{"Start":"00:03.480 ","End":"00:10.560","Text":"our continuing explanation of gas exchange across respiratory surfaces."},{"Start":"00:10.560 ","End":"00:12.630","Text":"In this section,"},{"Start":"00:12.630 ","End":"00:14.685","Text":"in these following videos,"},{"Start":"00:14.685 ","End":"00:22.470","Text":"we\u0027re going to understand better why it is that oxygen moves from our lungs"},{"Start":"00:22.470 ","End":"00:30.555","Text":"and into the bloodstream and from the bloodstream into our cells and vice-versa,"},{"Start":"00:30.555 ","End":"00:34.980","Text":"that carbon dioxide moves from the cells into"},{"Start":"00:34.980 ","End":"00:40.885","Text":"the bloodstream and then out into the air when we breathe?"},{"Start":"00:40.885 ","End":"00:46.050","Text":"The structure of the lungs that you can see here in this x-ray,"},{"Start":"00:46.050 ","End":"00:49.580","Text":"it has all these branches that we discussed in the previous video."},{"Start":"00:49.580 ","End":"00:53.870","Text":"The structure of that lung then maximizes the surface area,"},{"Start":"00:53.870 ","End":"00:58.430","Text":"so the gas diffusion will increase,"},{"Start":"00:58.430 ","End":"01:01.700","Text":"be as great as is possible."},{"Start":"01:01.700 ","End":"01:05.510","Text":"Because of the enormous number of the alveoli,"},{"Start":"01:05.510 ","End":"01:08.994","Text":"remember there are about 300 million in each human lung,"},{"Start":"01:08.994 ","End":"01:12.470","Text":"the surface area of the lungs is enormous."},{"Start":"01:12.470 ","End":"01:14.705","Text":"About 150 square meters."},{"Start":"01:14.705 ","End":"01:20.555","Text":"That\u0027s about the size of a tennis court, extremely large amounts."},{"Start":"01:20.555 ","End":"01:27.315","Text":"Of course, that facilitates the gas diffusion into and out of the lungs."},{"Start":"01:27.315 ","End":"01:31.910","Text":"Remember, oxygen then is going to be coming from the alveoli in"},{"Start":"01:31.910 ","End":"01:39.190","Text":"the lungs oxygen going into the bloodstream and carbon dioxide coming out."},{"Start":"01:39.190 ","End":"01:42.060","Text":"That as you can see, is in this picture as well,"},{"Start":"01:42.060 ","End":"01:45.500","Text":"and what we\u0027re going to do is we\u0027re going to discuss some of"},{"Start":"01:45.500 ","End":"01:50.120","Text":"the basic principles about gas exchange that will explain why it"},{"Start":"01:50.120 ","End":"01:53.800","Text":"is that oxygen moves from"},{"Start":"01:53.800 ","End":"01:58.730","Text":"the lungs into the bloodstream and carbon dioxide in the opposite direction."},{"Start":"01:58.730 ","End":"02:03.460","Text":"Of course, respiration occurs primarily through gas diffusion."},{"Start":"02:03.460 ","End":"02:07.475","Text":"Gases, as do other molecules,"},{"Start":"02:07.475 ","End":"02:10.355","Text":"move along a pressure gradient."},{"Start":"02:10.355 ","End":"02:14.690","Text":"That is, they diffuse from where the pressure is greater or where"},{"Start":"02:14.690 ","End":"02:20.300","Text":"the concentration is greater to where the concentration is lower."},{"Start":"02:20.300 ","End":"02:23.390","Text":"What we\u0027ll find is that in blood,"},{"Start":"02:23.390 ","End":"02:28.745","Text":"there is relatively low concentration of oxygen,"},{"Start":"02:28.745 ","End":"02:34.070","Text":"it\u0027s coming in the veins as they approach the alveoli."},{"Start":"02:34.070 ","End":"02:42.800","Text":"The concentration of oxygen in the alveoli will be higher than in the blood,"},{"Start":"02:42.800 ","End":"02:45.325","Text":"and therefore it will move into the blood,"},{"Start":"02:45.325 ","End":"02:49.615","Text":"and the opposite will be true of carbon dioxide."},{"Start":"02:49.615 ","End":"02:53.975","Text":"This then depletes the blood of"},{"Start":"02:53.975 ","End":"02:59.930","Text":"carbon dioxide and there in more oxygen is moved into the blood,"},{"Start":"02:59.930 ","End":"03:02.430","Text":"as we said before."},{"Start":"03:04.940 ","End":"03:11.030","Text":"The concentration gradients for each of these 2 components of oxygen and carbon dioxide"},{"Start":"03:11.030 ","End":"03:17.680","Text":"is what allows for gas exchange during respiration, during our breathing."},{"Start":"03:17.680 ","End":"03:22.300","Text":"Now, there is a concept called partial pressure and gas,"},{"Start":"03:22.300 ","End":"03:25.405","Text":"and that\u0027s very important because there, of course,"},{"Start":"03:25.405 ","End":"03:26.995","Text":"is a particular pressure,"},{"Start":"03:26.995 ","End":"03:30.580","Text":"air pressure that is composed of"},{"Start":"03:30.580 ","End":"03:35.440","Text":"several partial pressures of each of the different components."},{"Start":"03:35.440 ","End":"03:38.185","Text":"There are different gases we\u0027ve been talking about until now,"},{"Start":"03:38.185 ","End":"03:41.590","Text":"is oxygen and carbon dioxide,"},{"Start":"03:41.590 ","End":"03:49.795","Text":"and each of them has what\u0027s called a partial pressure in this mixture of gases,"},{"Start":"03:49.795 ","End":"03:53.980","Text":"and the total pressure, of course,"},{"Start":"03:53.980 ","End":"03:58.540","Text":"is the sum of each of these partial pressures that are the components."},{"Start":"03:58.540 ","End":"04:03.140","Text":"The partial pressure is going to be the pressure of each of them,"},{"Start":"04:03.140 ","End":"04:05.525","Text":"as we\u0027ll see individually."},{"Start":"04:05.525 ","End":"04:09.290","Text":"Importantly, the rate of diffusion,"},{"Start":"04:09.290 ","End":"04:17.670","Text":"the rate of diffusion of a gas is proportional to its partial pressure."},{"Start":"04:17.670 ","End":"04:23.285","Text":"We\u0027re going to be looking at a specific gas in this mixture,"},{"Start":"04:23.285 ","End":"04:26.990","Text":"and the rate of diffusion is not going to be dependent"},{"Start":"04:26.990 ","End":"04:31.380","Text":"on the concentrations of other gases,"},{"Start":"04:31.380 ","End":"04:38.920","Text":"it will be proportional to its own partial pressure within the total gas mixture."},{"Start":"04:38.920 ","End":"04:42.650","Text":"Now, the lung size, of course,"},{"Start":"04:42.650 ","End":"04:49.100","Text":"is going to be very important because we\u0027re going to want to have faster diffusion for"},{"Start":"04:49.100 ","End":"04:56.110","Text":"animals that require quicker respiration and that will be dependent on their activities."},{"Start":"04:56.110 ","End":"04:57.695","Text":"Cheetahs, for instance,"},{"Start":"04:57.695 ","End":"05:01.760","Text":"have a very high lung capacity and that"},{"Start":"05:01.760 ","End":"05:07.700","Text":"supports the very high oxygen demand that these cheetahs required during running."},{"Start":"05:07.700 ","End":"05:09.920","Text":"Whereas in elephants,"},{"Start":"05:09.920 ","End":"05:12.215","Text":"we have a similar situation,"},{"Start":"05:12.215 ","End":"05:13.940","Text":"but it\u0027s not the speed,"},{"Start":"05:13.940 ","End":"05:17.240","Text":"it\u0027s the size of the animal in elephants,"},{"Start":"05:17.240 ","End":"05:21.365","Text":"that will also requires them to have a very large lung capacity."},{"Start":"05:21.365 ","End":"05:22.985","Text":"Now, in humans,"},{"Start":"05:22.985 ","End":"05:25.100","Text":"this is determined of course by genetics,"},{"Start":"05:25.100 ","End":"05:26.960","Text":"by sex, yes,"},{"Start":"05:26.960 ","End":"05:29.570","Text":"males have larger bodies than females,"},{"Start":"05:29.570 ","End":"05:31.970","Text":"and so they have larger lungs as well,"},{"Start":"05:31.970 ","End":"05:37.700","Text":"and the height of the people and at maximal capacity in humans,"},{"Start":"05:37.700 ","End":"05:41.495","Text":"an average lungs can hold about 6 liters of air."},{"Start":"05:41.495 ","End":"05:48.409","Text":"The lung volume measures the amount of air for 1 function,"},{"Start":"05:48.409 ","End":"05:50.945","Text":"say inhalation or exhalation."},{"Start":"05:50.945 ","End":"05:57.180","Text":"We\u0027re talking here about the 6 liters is when we breathe in and when we inhale,"},{"Start":"05:57.180 ","End":"06:01.860","Text":"and that\u0027ll be this large lung capacity."}],"ID":30609},{"Watched":false,"Name":"Partial Pressures and Movement of Oxygen and Carbon Dioxide","Duration":"5m 21s","ChapterTopicVideoID":29031,"CourseChapterTopicPlaylistID":294414,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.420","Text":"So now that we\u0027ve looked at partial pressures"},{"Start":"00:03.420 ","End":"00:06.335","Text":"in gas pressure and we understand that better,"},{"Start":"00:06.335 ","End":"00:09.480","Text":"let\u0027s see how that fits in with the respiration."},{"Start":"00:09.480 ","End":"00:12.480","Text":"That is again, the movements of oxygen"},{"Start":"00:12.480 ","End":"00:16.275","Text":"from the lung and the alveolus into the bloodstream,"},{"Start":"00:16.275 ","End":"00:22.815","Text":"and the movement of carbon dioxide from the bloodstream into the lungs."},{"Start":"00:22.815 ","End":"00:27.390","Text":"The partial oxygen pressure in the lungs, remember,"},{"Start":"00:27.390 ","End":"00:29.700","Text":"we figured out how to calculate it,"},{"Start":"00:29.700 ","End":"00:35.775","Text":"is going to be roughly 100 millimeters of mercury."},{"Start":"00:35.775 ","End":"00:39.365","Text":"Whereas the partial pressure in"},{"Start":"00:39.365 ","End":"00:47.180","Text":"the incoming bloodstream is going to be about 40 millimeters of mercury,"},{"Start":"00:47.180 ","End":"00:55.490","Text":"so the oxygen will diffuse from the lung into the bloodstream."},{"Start":"00:55.490 ","End":"00:59.074","Text":"On the other hand, if we look at the carbon dioxide,"},{"Start":"00:59.074 ","End":"01:04.445","Text":"the carbon dioxide is at about 46 millimeters of mercury,"},{"Start":"01:04.445 ","End":"01:09.050","Text":"partial pressure dissolved in the blood,"},{"Start":"01:09.050 ","End":"01:11.825","Text":"whereas in the air,"},{"Start":"01:11.825 ","End":"01:15.680","Text":"it\u0027s only about 40 millimeters of mercury."},{"Start":"01:15.680 ","End":"01:18.995","Text":"Therefore, it will diffuse from where the pressure is higher,"},{"Start":"01:18.995 ","End":"01:20.225","Text":"that is in the blood,"},{"Start":"01:20.225 ","End":"01:22.665","Text":"and into the lungs."},{"Start":"01:22.665 ","End":"01:24.875","Text":"When an air mixture reaches the lung,"},{"Start":"01:24.875 ","End":"01:26.615","Text":"it gets first humidified."},{"Start":"01:26.615 ","End":"01:29.995","Text":"That\u0027s going to change the partial pressure as well,"},{"Start":"01:29.995 ","End":"01:32.135","Text":"and the pressure of the water vapor,"},{"Start":"01:32.135 ","End":"01:35.495","Text":"which is 47 millimeters of mercury,"},{"Start":"01:35.495 ","End":"01:40.760","Text":"will be included in the calculation of the total pressure, and of course,"},{"Start":"01:40.760 ","End":"01:42.344","Text":"in our calculations,"},{"Start":"01:42.344 ","End":"01:47.125","Text":"that water pressure is going to have to be subtracted from the atmospheric pressure."},{"Start":"01:47.125 ","End":"01:57.775","Text":"Here you can see that the total pressure will be 713 and not 760 at sea level."},{"Start":"01:57.775 ","End":"02:07.460","Text":"The partial pressure of oxygen in the lungs will be about 150 milliliters of oxygen."},{"Start":"02:07.460 ","End":"02:11.360","Text":"It\u0027s actually different than what\u0027s shown in this figure because there"},{"Start":"02:11.360 ","End":"02:15.770","Text":"is some equilibrium with the blood that comes in at about 150."},{"Start":"02:15.770 ","End":"02:18.370","Text":"That\u0027s what you can see up here."},{"Start":"02:18.370 ","End":"02:24.805","Text":"The partial pressure in the lungs is about 150 millimeters of mercury,"},{"Start":"02:24.805 ","End":"02:27.410","Text":"and the oxygen and carbon dioxide"},{"Start":"02:27.410 ","End":"02:30.095","Text":"in the lungs will flow according to their pressure gradient,"},{"Start":"02:30.095 ","End":"02:31.640","Text":"as we said before,"},{"Start":"02:31.640 ","End":"02:34.180","Text":"from high to low."},{"Start":"02:34.180 ","End":"02:37.340","Text":"We\u0027ve got different partial pressures."},{"Start":"02:37.340 ","End":"02:43.339","Text":"We\u0027ve got partial pressure of the carbon dioxide and of the oxygen."},{"Start":"02:43.339 ","End":"02:46.655","Text":"There is a ratio between these 2."},{"Start":"02:46.655 ","End":"02:51.740","Text":"The ratio of the CO_2 production to"},{"Start":"02:51.740 ","End":"02:58.525","Text":"the oxygen consumption in the body is somewhere between 0.7, and 1."},{"Start":"02:58.525 ","End":"03:03.785","Text":"Interestingly, when glucose is the diet of cells,"},{"Start":"03:03.785 ","End":"03:10.970","Text":"then this respiratory quotient will be about 1 because it\u0027s very efficient."},{"Start":"03:10.970 ","End":"03:18.525","Text":"When we start looking at other sources of energy like fat or protein,"},{"Start":"03:18.525 ","End":"03:22.220","Text":"then this quotient goes down to 0.8, and 0.7."},{"Start":"03:22.220 ","End":"03:24.260","Text":"If we\u0027re talking about fat or fuel,"},{"Start":"03:24.260 ","End":"03:29.210","Text":"fat is bit more efficient than protein when it\u0027s burned,"},{"Start":"03:29.210 ","End":"03:32.495","Text":"and therefore, this quotient will depend on these things."},{"Start":"03:32.495 ","End":"03:37.550","Text":"In any case, there is this quotient which you will see will be important in"},{"Start":"03:37.550 ","End":"03:44.450","Text":"calculating how much oxygen and how much carbon dioxide goes in each direction."},{"Start":"03:44.450 ","End":"03:52.235","Text":"This respiratory quotient, the RQ of a pressure of oxygen,"},{"Start":"03:52.235 ","End":"03:57.860","Text":"the RQ is used to calculate the partial pressure of oxygen in the alveoli."},{"Start":"03:57.860 ","End":"04:02.320","Text":"That\u0027s the PO_2 within the lung,"},{"Start":"04:02.320 ","End":"04:05.735","Text":"and the partial pressure of oxygen in the lungs,"},{"Start":"04:05.735 ","End":"04:07.925","Text":"as we said, was about 150."},{"Start":"04:07.925 ","End":"04:09.995","Text":"But the inspired air,"},{"Start":"04:09.995 ","End":"04:11.540","Text":"that\u0027s the air that goes in,"},{"Start":"04:11.540 ","End":"04:15.665","Text":"mixes with residual air which was there and that\u0027s going to lower,"},{"Start":"04:15.665 ","End":"04:20.705","Text":"of course, the partial pressure of the oxygen in the alveoli,"},{"Start":"04:20.705 ","End":"04:25.505","Text":"as we saw in that previous diagram."},{"Start":"04:25.505 ","End":"04:28.970","Text":"The O_2 concentration, the oxygen concentration in lungs,"},{"Start":"04:28.970 ","End":"04:33.395","Text":"is lower than the air outside the body, of course."},{"Start":"04:33.395 ","End":"04:36.710","Text":"To calculate this, if we know the RQ,"},{"Start":"04:36.710 ","End":"04:43.505","Text":"then the partial pressure of oxygen in the alveoli is going to be the inspired."},{"Start":"04:43.505 ","End":"04:49.580","Text":"That\u0027s how much the partial pressure of oxygen that we breathe in,"},{"Start":"04:49.580 ","End":"04:54.290","Text":"minus what it is in the alveoli over the RQ."},{"Start":"04:54.290 ","End":"04:55.835","Text":"If you plug in the numbers,"},{"Start":"04:55.835 ","End":"05:00.965","Text":"remember the exterior partial pressure was 150 for oxygen,"},{"Start":"05:00.965 ","End":"05:07.385","Text":"then what we get is that it\u0027s roughly 100 millimeters of mercury in the alveoli,"},{"Start":"05:07.385 ","End":"05:09.215","Text":"as we mentioned early."},{"Start":"05:09.215 ","End":"05:13.405","Text":"Therefore, oxygen will flow from the inspired air,"},{"Start":"05:13.405 ","End":"05:17.600","Text":"which is a 150 into the bloodstream,"},{"Start":"05:17.600 ","End":"05:22.110","Text":"which is going to be lower than that."}],"ID":30610},{"Watched":false,"Name":"The importance of partial pressure in movement of oxygen and carbon dioxide","Duration":"3m 50s","ChapterTopicVideoID":29032,"CourseChapterTopicPlaylistID":294414,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.310","Text":"Welcome back to our continuing discussion of"},{"Start":"00:02.310 ","End":"00:06.134","Text":"gas exchange across the alveoli and in this video,"},{"Start":"00:06.134 ","End":"00:10.530","Text":"we\u0027ll go into a bit more detail than we have until now."},{"Start":"00:10.530 ","End":"00:14.130","Text":"Oxygen diffuses, as we\u0027ve mentioned before,"},{"Start":"00:14.130 ","End":"00:16.680","Text":"from the alveoli into the capillaries."},{"Start":"00:16.680 ","End":"00:18.600","Text":"In these figures now,"},{"Start":"00:18.600 ","End":"00:20.700","Text":"we\u0027ll see the alveoli on top with"},{"Start":"00:20.700 ","End":"00:25.370","Text":"various partial pressures and the partial pressures that are in the circulatory system"},{"Start":"00:25.370 ","End":"00:32.525","Text":"where we have the red that\u0027s going to be showing the oxygenated blood,"},{"Start":"00:32.525 ","End":"00:37.370","Text":"which is going to go through the circulatory system to the cells and then"},{"Start":"00:37.370 ","End":"00:43.305","Text":"eventually become less and less oxygenated until eventually,"},{"Start":"00:43.305 ","End":"00:47.440","Text":"we have this figure blue and a lower amount."},{"Start":"00:47.440 ","End":"00:50.300","Text":"In the lungs, the oxygen diffuses out of the alveoli"},{"Start":"00:50.300 ","End":"00:53.390","Text":"and into the capillaries that are surrounding them, of course,"},{"Start":"00:53.390 ","End":"01:03.730","Text":"and about 98 percent of the oxygen that goes in actually is bound by hemoglobin."},{"Start":"01:03.730 ","End":"01:06.335","Text":"As we know in red blood cells,"},{"Start":"01:06.335 ","End":"01:11.419","Text":"we have this pigment hemoglobin which binds oxygen very strongly."},{"Start":"01:11.419 ","End":"01:18.715","Text":"It\u0027s not just dissolved in the blood that helps the system significantly."},{"Start":"01:18.715 ","End":"01:25.400","Text":"The alveoli have a higher partial pressure of oxygen."},{"Start":"01:25.400 ","End":"01:27.560","Text":"Then in the blood,"},{"Start":"01:27.560 ","End":"01:30.950","Text":"as we\u0027ve said, about a 100 yes,"},{"Start":"01:30.950 ","End":"01:35.030","Text":"to about 40 of the incoming blood and therefore"},{"Start":"01:35.030 ","End":"01:40.160","Text":"the oxygen is going to diffuse alveoli and into the blood, binding the hemoglobin."},{"Start":"01:40.160 ","End":"01:47.140","Text":"Now let\u0027s look at carbon dioxide diffusion from the capillaries into the alveoli."},{"Start":"01:47.140 ","End":"01:50.284","Text":"Here we\u0027re looking at carbon dioxide."},{"Start":"01:50.284 ","End":"01:52.970","Text":"Carbon dioxide is going to be at"},{"Start":"01:52.970 ","End":"01:57.064","Text":"about 40 millimeters of mercury as we mentioned in the alveoli,"},{"Start":"01:57.064 ","End":"02:05.220","Text":"whereas in the bloodstream it\u0027s going to be 45 millimeters that\u0027s what\u0027s coming in"},{"Start":"02:05.220 ","End":"02:09.800","Text":"the capillaries that are coming into the alveoli and therefore it\u0027s going to be"},{"Start":"02:09.800 ","End":"02:15.720","Text":"higher than the 40 and it will then diffuse out."},{"Start":"02:16.090 ","End":"02:24.530","Text":"That\u0027s what this says here and note that the oxygen and the carbon dioxide"},{"Start":"02:24.530 ","End":"02:28.025","Text":"move independently of each other because they\u0027re dependent"},{"Start":"02:28.025 ","End":"02:32.135","Text":"on the partial pressure of each of them independently,"},{"Start":"02:32.135 ","End":"02:36.145","Text":"they each have their own pressure gradients."},{"Start":"02:36.145 ","End":"02:38.465","Text":"Looking at these together,"},{"Start":"02:38.465 ","End":"02:42.245","Text":"we\u0027ve got oxygen coming in and"},{"Start":"02:42.245 ","End":"02:48.425","Text":"carbon dioxide going out because of these different partial pressures,"},{"Start":"02:48.425 ","End":"02:52.940","Text":"because of the pressure differences between the tissues and"},{"Start":"02:52.940 ","End":"02:55.040","Text":"the blood and we said we have"},{"Start":"02:55.040 ","End":"02:58.674","Text":"a similar situation which is going on at the peripheral tissues."},{"Start":"02:58.674 ","End":"03:03.170","Text":"That we have CO_2 going from the peripheral tissue which is"},{"Start":"03:03.170 ","End":"03:07.735","Text":"at about 45 millimeters going into the bloodstream."},{"Start":"03:07.735 ","End":"03:16.505","Text":"It\u0027s greater than 45 millimeters and we have a similar situation with oxygen,"},{"Start":"03:16.505 ","End":"03:22.660","Text":"which is leaving the bloodstream and going into the peripheral tissue."},{"Start":"03:22.660 ","End":"03:29.395","Text":"This drives these 2 S\u0027s in the appropriate direction."},{"Start":"03:29.395 ","End":"03:34.250","Text":"Blood returning to the lungs has a partial pressure of"},{"Start":"03:34.250 ","End":"03:38.990","Text":"oxygen about 40 millimeters and a partial pressure of carbon dioxide of"},{"Start":"03:38.990 ","End":"03:43.580","Text":"45 millimeters of pressure and"},{"Start":"03:43.580 ","End":"03:49.350","Text":"that\u0027s explains the gas exchange between the capillaries and the alveoli."}],"ID":30611},{"Watched":false,"Name":"Human Lung Capacities","Duration":"5m 26s","ChapterTopicVideoID":29033,"CourseChapterTopicPlaylistID":294414,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.205","Text":"In the previous video,"},{"Start":"00:02.205 ","End":"00:09.030","Text":"we discussed lung sizes in animals and how it was important for them"},{"Start":"00:09.030 ","End":"00:16.125","Text":"to have a lung which was large enough to support the particular needs of that animal."},{"Start":"00:16.125 ","End":"00:18.479","Text":"A cheetah and an elephant were examples."},{"Start":"00:18.479 ","End":"00:20.670","Text":"Now, let\u0027s look at humans."},{"Start":"00:20.670 ","End":"00:23.940","Text":"In humans, the size is determined by genetics,"},{"Start":"00:23.940 ","End":"00:25.935","Text":"the sex, and the height."},{"Start":"00:25.935 ","End":"00:31.845","Text":"Of course, males are larger and require larger lungs."},{"Start":"00:31.845 ","End":"00:34.290","Text":"At maximal capacity,"},{"Start":"00:34.290 ","End":"00:37.410","Text":"an average lung can hold about 6 liters of air."},{"Start":"00:37.410 ","End":"00:40.880","Text":"The lung volume measures the amount of air"},{"Start":"00:40.880 ","End":"00:44.959","Text":"for one of these functions such as inhalation or exhalation."},{"Start":"00:44.959 ","End":"00:51.590","Text":"What we\u0027re going to do now is discuss various definitions of"},{"Start":"00:51.590 ","End":"00:58.360","Text":"lung capacity and different parts of our inhalation, exhalation."},{"Start":"00:58.360 ","End":"00:59.990","Text":"These will be important,"},{"Start":"00:59.990 ","End":"01:01.640","Text":"as you will see a bit later,"},{"Start":"01:01.640 ","End":"01:06.065","Text":"to understand why it is that oxygen moves from"},{"Start":"01:06.065 ","End":"01:12.040","Text":"the lungs into the bloodstream and carbon dioxide moves out."},{"Start":"01:12.040 ","End":"01:20.055","Text":"The total lung capacity measures 2 or more volumes, it turns out."},{"Start":"01:20.055 ","End":"01:24.020","Text":"For an example, we can say that how"},{"Start":"01:24.020 ","End":"01:28.610","Text":"much one can inhale from one end of a maximal inhalation."},{"Start":"01:28.610 ","End":"01:34.070","Text":"When we inhale, we first can exhale all the way and then"},{"Start":"01:34.070 ","End":"01:40.880","Text":"inhale all the way and that can be a definition of a total lung capacity."},{"Start":"01:40.880 ","End":"01:47.135","Text":"Now, the lung volumes can be divided into 4 different parts."},{"Start":"01:47.135 ","End":"01:51.560","Text":"There\u0027s something that we call a tidal volume."},{"Start":"01:51.560 ","End":"01:55.190","Text":"That\u0027s the amount of air that is inspired,"},{"Start":"01:55.190 ","End":"01:59.125","Text":"breathed in and expired during a normal breath."},{"Start":"01:59.125 ","End":"02:01.995","Text":"That\u0027s about 1/2 a liter, so a normal breath."},{"Start":"02:01.995 ","End":"02:05.615","Text":"This is the tidal volume that you can see here."},{"Start":"02:05.615 ","End":"02:08.825","Text":"There\u0027s the expiratory reserve volume."},{"Start":"02:08.825 ","End":"02:14.405","Text":"After you breathe, you can breathe more out than you normally did."},{"Start":"02:14.405 ","End":"02:16.710","Text":"That would be this part over here,"},{"Start":"02:16.710 ","End":"02:18.450","Text":"yes, that you breathe out."},{"Start":"02:18.450 ","End":"02:21.650","Text":"That is the expiratory reserve volume."},{"Start":"02:21.650 ","End":"02:25.810","Text":"We have the inspiratory reserve volume, the IRV."},{"Start":"02:25.810 ","End":"02:33.320","Text":"That\u0027s what we can breathe in more than we normally breathe in the regular breath."},{"Start":"02:33.320 ","End":"02:35.570","Text":"Yes, that\u0027s the additional amount of air."},{"Start":"02:35.570 ","End":"02:38.270","Text":"We have the residual volume."},{"Start":"02:38.270 ","End":"02:44.855","Text":"That\u0027s the amount of air that is left after expiatory reserve volume is exhaled."},{"Start":"02:44.855 ","End":"02:48.860","Text":"After we\u0027ve exhaled as much as we can,"},{"Start":"02:48.860 ","End":"02:55.139","Text":"there still is some volume that\u0027s left in our lungs."},{"Start":"02:55.139 ","End":"02:57.720","Text":"We can\u0027t exhale further than that, otherwise,"},{"Start":"02:57.720 ","End":"03:01.065","Text":"we would damage our lungs."},{"Start":"03:01.065 ","End":"03:02.930","Text":"That\u0027s important, therefore,"},{"Start":"03:02.930 ","End":"03:07.010","Text":"this volume for preventing large fluctuations in these gases."},{"Start":"03:07.010 ","End":"03:09.795","Text":"We\u0027ll see that\u0027s important soon."},{"Start":"03:09.795 ","End":"03:17.029","Text":"Of course, since we can\u0027t exhale further than the ERV,"},{"Start":"03:17.029 ","End":"03:18.905","Text":"the expiratory reserve volume,"},{"Start":"03:18.905 ","End":"03:23.785","Text":"that must be calculated rather than measured."},{"Start":"03:23.785 ","End":"03:28.730","Text":"What\u0027s important then really is this vital capacity."},{"Start":"03:28.730 ","End":"03:31.940","Text":"That\u0027s the maximum amount of air that can be inhaled or"},{"Start":"03:31.940 ","End":"03:35.105","Text":"exhaled during the respiratory cycle."},{"Start":"03:35.105 ","End":"03:38.270","Text":"That\u0027s what we actually breathe and"},{"Start":"03:38.270 ","End":"03:41.480","Text":"that will be then the sum of the expiatory reserve volume,"},{"Start":"03:41.480 ","End":"03:44.930","Text":"the tidal volume, and the inspiratory reserve volume."},{"Start":"03:44.930 ","End":"03:47.440","Text":"These 3 pieces,"},{"Start":"03:47.440 ","End":"03:49.010","Text":"as we\u0027ve seen before."},{"Start":"03:49.010 ","End":"03:53.450","Text":"In addition to that, we have the inspiratory capacity."},{"Start":"03:53.450 ","End":"03:57.620","Text":"That is how much we can breathe in."},{"Start":"03:57.620 ","End":"04:03.080","Text":"That\u0027ll include the tidal capacity that we saw earlier."},{"Start":"04:03.080 ","End":"04:09.065","Text":"We have a functional residual capacity that we can describe,"},{"Start":"04:09.065 ","End":"04:14.910","Text":"which will include both the respiratory reserve volume and the residual volume."},{"Start":"04:14.910 ","End":"04:18.655","Text":"This is what we breathe out plus what we can\u0027t breathe out."},{"Start":"04:18.655 ","End":"04:25.745","Text":"Measures the amount of additional air that can be exhaled after a normal exhalation."},{"Start":"04:25.745 ","End":"04:30.785","Text":"Finally, we have the total lung capacity that we started with."},{"Start":"04:30.785 ","End":"04:35.925","Text":"That\u0027s the total amount of air that the lung can hold,"},{"Start":"04:35.925 ","End":"04:38.040","Text":"yes, the total lung capacity."},{"Start":"04:38.040 ","End":"04:40.730","Text":"That\u0027ll be the sum of the residual volume,"},{"Start":"04:40.730 ","End":"04:43.100","Text":"expiratory reserve volume, the tidal volume,"},{"Start":"04:43.100 ","End":"04:46.390","Text":"and the inspiratory reserve volume,"},{"Start":"04:46.390 ","End":"04:48.255","Text":"the total lung capacity."},{"Start":"04:48.255 ","End":"04:54.380","Text":"All of this is summarized in this table which I suggest that"},{"Start":"04:54.380 ","End":"05:01.715","Text":"you print out and look at more carefully on your own time."},{"Start":"05:01.715 ","End":"05:06.320","Text":"I\u0027ll just add that the typical volumes in"},{"Start":"05:06.320 ","End":"05:10.925","Text":"liters of all these are also described in this table."},{"Start":"05:10.925 ","End":"05:14.135","Text":"We had said the total lung capacity was on the order"},{"Start":"05:14.135 ","End":"05:17.630","Text":"of 6 liters and here you can see what"},{"Start":"05:17.630 ","End":"05:25.290","Text":"the various proportions are for the different parts of our breathing capacity."}],"ID":30612}],"Thumbnail":null,"ID":294414},{"Name":"Breathing","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Breathing in Mammals","Duration":"5m 17s","ChapterTopicVideoID":29008,"CourseChapterTopicPlaylistID":294415,"HasSubtitles":true,"ThumbnailPath":"https://www.proprep.uk/Images/Videos_Thumbnails/29008.jpeg","UploadDate":"2022-05-29T12:03:36.1200000","DurationForVideoObject":"PT5M17S","Description":null,"MetaTitle":"Breathing in Mammals: Video + Workbook | Proprep","MetaDescription":"The Respiratory System - Breathing. Watch the video made by an expert in the field. Download the workbook and maximize your learning.","Canonical":"https://www.proprep.uk/general-modules/all/introduction-to-biology/the-respiratory-system/breathing/vid30594","VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.154","Text":"Let\u0027s continue our discussion of breathing by looking at breathing in mammals,"},{"Start":"00:05.154 ","End":"00:08.020","Text":"mammalian breathing, that\u0027s going to be us in the end."},{"Start":"00:08.020 ","End":"00:11.455","Text":"All mammals have these well-developed lungs,"},{"Start":"00:11.455 ","End":"00:15.955","Text":"not like the amphibians that we saw before and those are the main organs for breathing."},{"Start":"00:15.955 ","End":"00:18.765","Text":"Usually, it\u0027s the only organ."},{"Start":"00:18.765 ","End":"00:21.205","Text":"In all of these cases,"},{"Start":"00:21.205 ","End":"00:24.310","Text":"we have a diaphragm,"},{"Start":"00:24.310 ","End":"00:27.685","Text":"which is going to be moving the lungs, as we\u0027ll see."},{"Start":"00:27.685 ","End":"00:30.500","Text":"At least that\u0027s one thing that moves the lungs."},{"Start":"00:30.500 ","End":"00:35.710","Text":"The lungs have to have this capacity which has evolved to"},{"Start":"00:35.710 ","End":"00:40.635","Text":"support the particular animal\u0027s activities as we saw in the previous videos."},{"Start":"00:40.635 ","End":"00:45.005","Text":"During inhalation, the lungs will expand with the air"},{"Start":"00:45.005 ","End":"00:50.030","Text":"and the oxygen then diffuses across the lung surface and enters the bloodstream."},{"Start":"00:50.030 ","End":"00:56.845","Text":"During exhalation, the lungs will expel the air and the lung volume decreases."},{"Start":"00:56.845 ","End":"00:58.730","Text":"How does that happen?"},{"Start":"00:58.730 ","End":"01:02.375","Text":"Well, it\u0027s really based on something called Boyle\u0027s Law."},{"Start":"01:02.375 ","End":"01:06.545","Text":"Boyle\u0027s Law says that in a closed space,"},{"Start":"01:06.545 ","End":"01:09.710","Text":"like this space that we have over here,"},{"Start":"01:09.710 ","End":"01:13.220","Text":"the pressure and volume are inversely related."},{"Start":"01:13.220 ","End":"01:16.880","Text":"What does that mean? That means that if we have, say,"},{"Start":"01:16.880 ","End":"01:21.905","Text":"a piston here and we decrease the volume in this closed space,"},{"Start":"01:21.905 ","End":"01:27.725","Text":"of course, the pressure is going to go up and vice versa."},{"Start":"01:27.725 ","End":"01:30.950","Text":"Yes, if we have a closed space,"},{"Start":"01:30.950 ","End":"01:36.928","Text":"let\u0027s say like this and it has a particular pressure in there as we move it up,"},{"Start":"01:36.928 ","End":"01:41.070","Text":"yes, the air pressure will go down."},{"Start":"01:41.070 ","End":"01:46.274","Text":"The relationship between gas pressure and volume we\u0027ll find out,"},{"Start":"01:46.274 ","End":"01:48.620","Text":"that helps explain the mechanics of breathing."},{"Start":"01:48.620 ","End":"01:54.260","Text":"Because we have a closed space in our lungs and the piston that we saw in"},{"Start":"01:54.260 ","End":"02:00.365","Text":"the previous figure is going to be similar to the diaphragm,"},{"Start":"02:00.365 ","End":"02:04.715","Text":"which is going to be moving up and down."},{"Start":"02:04.715 ","End":"02:08.660","Text":"It\u0027s going to be moving down,"},{"Start":"02:08.660 ","End":"02:10.835","Text":"down as we inhale,"},{"Start":"02:10.835 ","End":"02:13.390","Text":"and up as we exhale."},{"Start":"02:13.390 ","End":"02:18.695","Text":"The volume of the thorax activity increases because of the diaphragm contraction."},{"Start":"02:18.695 ","End":"02:22.175","Text":"Therefore, the pressure decreases by Boyle\u0027s Law,"},{"Start":"02:22.175 ","End":"02:25.640","Text":"and that allows us to inhale."},{"Start":"02:25.640 ","End":"02:30.680","Text":"Air will come in because the pressure will be larger outside than inside,"},{"Start":"02:30.680 ","End":"02:32.425","Text":"so it\u0027s going to go in."},{"Start":"02:32.425 ","End":"02:36.335","Text":"The opposite is going to be true when we exhale."},{"Start":"02:36.335 ","End":"02:39.690","Text":"Now the part which is flexible are the lungs."},{"Start":"02:39.690 ","End":"02:42.275","Text":"The bronchioles and bronchi."},{"Start":"02:42.275 ","End":"02:47.045","Text":"Yes, in here are stiff and they don\u0027t change in size."},{"Start":"02:47.045 ","End":"02:49.130","Text":"It\u0027s just really the alveoli,"},{"Start":"02:49.130 ","End":"02:52.430","Text":"and the structures right around them."},{"Start":"02:52.430 ","End":"02:57.575","Text":"Now in addition to the diaphragm moving now we\u0027re looking at a side view."},{"Start":"02:57.575 ","End":"03:01.190","Text":"The chest wall can expand away from the lungs."},{"Start":"03:01.190 ","End":"03:05.755","Text":"We all know that our chest goes in and out when we breathe."},{"Start":"03:05.755 ","End":"03:11.630","Text":"That is an addition to the diaphragm that helps increase the volume of"},{"Start":"03:11.630 ","End":"03:18.130","Text":"our lungs and helps decrease them as we\u0027re breathing out."},{"Start":"03:18.130 ","End":"03:23.105","Text":"We\u0027re inflating and deflating the lung with every breath."},{"Start":"03:23.105 ","End":"03:28.555","Text":"The lungs can recoil to force the air out when we want to exhale."},{"Start":"03:28.555 ","End":"03:31.350","Text":"We have these intercostal muscles,"},{"Start":"03:31.350 ","End":"03:33.835","Text":"which are doing a lot of the work."},{"Start":"03:33.835 ","End":"03:36.020","Text":"Let\u0027s look at the diaphragm for a moment."},{"Start":"03:36.020 ","End":"03:42.319","Text":"We said it goes down when we inhale and it goes up when we exhale,"},{"Start":"03:42.319 ","End":"03:46.820","Text":"increasing and decreasing the pressure on the lungs."},{"Start":"03:46.820 ","End":"03:51.365","Text":"Now, it\u0027s the movement of air, therefore is passive."},{"Start":"03:51.365 ","End":"03:57.395","Text":"They\u0027re not any muscles which are moving to move the air in and out."},{"Start":"03:57.395 ","End":"04:03.570","Text":"It\u0027s just because of the difference of air pressure really that moves things."},{"Start":"04:03.570 ","End":"04:06.395","Text":"Now things are sliding past one another."},{"Start":"04:06.395 ","End":"04:11.210","Text":"We have the lungs which are sliding against the ribs,"},{"Start":"04:11.210 ","End":"04:16.645","Text":"ribcage, and the intercostal muscles and that would create a lot of friction."},{"Start":"04:16.645 ","End":"04:21.725","Text":"We have what are called pulmonary pleura they are these membranes,"},{"Start":"04:21.725 ","End":"04:25.580","Text":"the serous membranes and it\u0027s a membrane that folds back on itself"},{"Start":"04:25.580 ","End":"04:30.330","Text":"to form a 2-layered membranous pleural sac."},{"Start":"04:30.330 ","End":"04:38.074","Text":"Between these two parts will see that there is a pleural cavity that\u0027s filled by fluids,"},{"Start":"04:38.074 ","End":"04:40.540","Text":"which is going to lubricate all of this."},{"Start":"04:40.540 ","End":"04:43.145","Text":"We have the visceral pleura,"},{"Start":"04:43.145 ","End":"04:45.815","Text":"which is covering the lung itself."},{"Start":"04:45.815 ","End":"04:47.825","Text":"We have the parietal pleura,"},{"Start":"04:47.825 ","End":"04:50.965","Text":"which is adjacent to the muscle and into the ribs."},{"Start":"04:50.965 ","End":"04:54.590","Text":"We have the cavity which is between the two of them,"},{"Start":"04:54.590 ","End":"05:00.355","Text":"the pleural cavity and that is what it\u0027s going to lubricate the situation while we\u0027re"},{"Start":"05:00.355 ","End":"05:06.515","Text":"breathing because these two different regions are going to be moving a bit differently."},{"Start":"05:06.515 ","End":"05:08.360","Text":"Now sometimes the tissue,"},{"Start":"05:08.360 ","End":"05:13.445","Text":"this pleural area can become inflamed and that could hurt."},{"Start":"05:13.445 ","End":"05:16.920","Text":"That would be called pleurisy."}],"ID":30594},{"Watched":false,"Name":"Breathing in Animals Other than Mammals","Duration":"5m 55s","ChapterTopicVideoID":29009,"CourseChapterTopicPlaylistID":294415,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.335","Text":"I\u0027m glad you\u0027re back for discussion of breathing."},{"Start":"00:04.335 ","End":"00:05.640","Text":"In the previous section,"},{"Start":"00:05.640 ","End":"00:09.420","Text":"we talked about gas exchange in and out of the lungs,"},{"Start":"00:09.420 ","End":"00:11.640","Text":"and in this section, we\u0027re going to be talking more"},{"Start":"00:11.640 ","End":"00:14.445","Text":"about the mechanics of the breathing."},{"Start":"00:14.445 ","End":"00:19.590","Text":"Now, there are 2 main types of respiratory organs, of course,"},{"Start":"00:19.590 ","End":"00:24.885","Text":"they\u0027re the lungs that we know about and that exchanges gases into the air."},{"Start":"00:24.885 ","End":"00:32.550","Text":"But in addition, there are gills that are for aquatic respiration let\u0027s say in fish,"},{"Start":"00:32.550 ","End":"00:37.295","Text":"for instance which do the gas exchange straight into water."},{"Start":"00:37.295 ","End":"00:42.590","Text":"Now, both gills and lungs can actually occur in the same animal,"},{"Start":"00:42.590 ","End":"00:45.845","Text":"like in salamanders sometimes we\u0027ll find"},{"Start":"00:45.845 ","End":"00:50.089","Text":"that both of them exist at the same time and in other cases,"},{"Start":"00:50.089 ","End":"00:53.270","Text":"say in the development of frogs and tadpoles,"},{"Start":"00:53.270 ","End":"00:57.305","Text":"you\u0027ll have gills and then later lungs as we\u0027ll see in a moment."},{"Start":"00:57.305 ","End":"01:02.450","Text":"Now, some vertebrates, in addition to the lungs and gills,"},{"Start":"01:02.450 ","End":"01:09.315","Text":"can also exchange gases through their skin and we\u0027ll see that in a minute too."},{"Start":"01:09.315 ","End":"01:15.410","Text":"In addition, there are occasionally other organs like in some turtles,"},{"Start":"01:15.410 ","End":"01:20.240","Text":"there\u0027s the cloaca at the end of its digestive tract."},{"Start":"01:20.240 ","End":"01:24.695","Text":"Interestingly, what it can do is it can bring water in from the outside."},{"Start":"01:24.695 ","End":"01:27.260","Text":"These are for aquatic turtles,"},{"Start":"01:27.260 ","End":"01:32.910","Text":"and it goes into some sack over here and then the water that\u0027s in the sack,"},{"Start":"01:32.910 ","End":"01:35.010","Text":"of course, contains oxygen."},{"Start":"01:35.010 ","End":"01:40.415","Text":"It can then exchange gases in the cloaca"},{"Start":"01:40.415 ","End":"01:46.425","Text":"into the bloodstream by a specialized little capillaries that do that gas exchange,"},{"Start":"01:46.425 ","End":"01:52.515","Text":"so that\u0027s a particular kind of respiration that occurs in these turtles."},{"Start":"01:52.515 ","End":"01:54.540","Text":"As we mentioned before,"},{"Start":"01:54.540 ","End":"02:03.590","Text":"tadpoles often have gills in order to breathe but as the tadpoles turn into frogs,"},{"Start":"02:03.590 ","End":"02:08.480","Text":"they develop primitive lungs that grow."},{"Start":"02:08.480 ","End":"02:11.015","Text":"They\u0027re not as complicated,"},{"Start":"02:11.015 ","End":"02:12.740","Text":"and as branched as we have,"},{"Start":"02:12.740 ","End":"02:15.200","Text":"let\u0027s say in us and at the same time,"},{"Start":"02:15.200 ","End":"02:17.149","Text":"the gills will disappear."},{"Start":"02:17.149 ","End":"02:18.830","Text":"In addition to this though,"},{"Start":"02:18.830 ","End":"02:23.620","Text":"these amphibians often will breathe by diffusion across the skin and so"},{"Start":"02:23.620 ","End":"02:28.685","Text":"here\u0027s some skin of a frog and there are these areas"},{"Start":"02:28.685 ","End":"02:36.080","Text":"in which the surface area of the skin is enlarged and the air can diffuse in and out of"},{"Start":"02:36.080 ","End":"02:40.490","Text":"these vesicles and allow gas exchange"},{"Start":"02:40.490 ","End":"02:45.125","Text":"back and forth into the blood that\u0027s around these areas."},{"Start":"02:45.125 ","End":"02:46.895","Text":"Of course, in order for this to work,"},{"Start":"02:46.895 ","End":"02:50.300","Text":"the skin must remain moist."},{"Start":"02:50.300 ","End":"02:52.560","Text":"Now, in mammals,"},{"Start":"02:52.560 ","End":"02:54.995","Text":"we have a diaphragm as we\u0027ll see,"},{"Start":"02:54.995 ","End":"02:57.185","Text":"which moves gases in and out."},{"Start":"02:57.185 ","End":"02:59.570","Text":"But not all organisms have a diaphragm."},{"Start":"02:59.570 ","End":"03:00.890","Text":"In frogs for instance,"},{"Start":"03:00.890 ","End":"03:04.835","Text":"there\u0027s a fairly complicated system of moving"},{"Start":"03:04.835 ","End":"03:09.500","Text":"air in and out of the frog in which there is a glottis,"},{"Start":"03:09.500 ","End":"03:11.600","Text":"there\u0027s a place in the back of the throat,"},{"Start":"03:11.600 ","End":"03:15.605","Text":"which can be either closed or open,"},{"Start":"03:15.605 ","End":"03:20.520","Text":"and of course, the mouth can be either closed or open."},{"Start":"03:20.520 ","End":"03:28.430","Text":"By moving its muscles of its chest cavity back-and-forth and also the muscles that"},{"Start":"03:28.430 ","End":"03:36.590","Text":"are on its throat and by opening and closing its nose or the nares here,"},{"Start":"03:36.590 ","End":"03:39.185","Text":"it can move air in and out."},{"Start":"03:39.185 ","End":"03:43.360","Text":"The details of this for our purposes are not so important."},{"Start":"03:43.360 ","End":"03:50.030","Text":"In birds, we have another special requirement and that is that we need"},{"Start":"03:50.030 ","End":"03:53.660","Text":"an awful lot of oxygen to be able to get in because the muscles that"},{"Start":"03:53.660 ","End":"03:58.030","Text":"are operating the wings require a lot of oxygen."},{"Start":"03:58.030 ","End":"04:01.880","Text":"We want to make the gas exchange as efficient as possible,"},{"Start":"04:01.880 ","End":"04:03.350","Text":"and for that purpose,"},{"Start":"04:03.350 ","End":"04:06.980","Text":"birds have various air sacs so here are"},{"Start":"04:06.980 ","End":"04:09.980","Text":"our posterior thoracic air sacs and then they are"},{"Start":"04:09.980 ","End":"04:14.575","Text":"anterior air sacs at different air sacs in addition to the lungs."},{"Start":"04:14.575 ","End":"04:16.310","Text":"Air, as we\u0027ll see in a moment,"},{"Start":"04:16.310 ","End":"04:20.725","Text":"moves between the sacks and the lungs,"},{"Start":"04:20.725 ","End":"04:25.100","Text":"and that is done in 2 cycles of respiration."},{"Start":"04:25.100 ","End":"04:28.790","Text":"It\u0027s necessary not only to support the amount"},{"Start":"04:28.790 ","End":"04:32.645","Text":"of oxygen that the bird needs during normal flight,"},{"Start":"04:32.645 ","End":"04:34.205","Text":"but in many cases,"},{"Start":"04:34.205 ","End":"04:39.970","Text":"birds can fly at very high altitudes and the concentration of oxygen there will be low."},{"Start":"04:39.970 ","End":"04:44.185","Text":"They\u0027ve evolved these lungs and air sacs to solve the problem,"},{"Start":"04:44.185 ","End":"04:46.105","Text":"now let\u0027s see what happens."},{"Start":"04:46.105 ","End":"04:54.020","Text":"As I mentioned, there are 2 of these cycles of intake and exhalation."},{"Start":"04:54.020 ","End":"04:55.820","Text":"In the first cycle,"},{"Start":"04:55.820 ","End":"05:04.040","Text":"what happens is the air moves in to a posterior air sac and then it moves out in"},{"Start":"05:04.040 ","End":"05:07.520","Text":"the next breath into the lungs where"},{"Start":"05:07.520 ","End":"05:12.530","Text":"the gas exchange is occurring at the same time we have the air that was in them,"},{"Start":"05:12.530 ","End":"05:14.450","Text":"not move outside but move into"},{"Start":"05:14.450 ","End":"05:19.090","Text":"the anterior air sac and then in the next breath, it moves out."},{"Start":"05:19.090 ","End":"05:21.835","Text":"We have the first exhalation,"},{"Start":"05:21.835 ","End":"05:24.935","Text":"inhalation, we have air going in."},{"Start":"05:24.935 ","End":"05:26.285","Text":"The first exhalation,"},{"Start":"05:26.285 ","End":"05:28.910","Text":"we have it going out into the lungs."},{"Start":"05:28.910 ","End":"05:34.240","Text":"Then we have a second inhalation in which the air is going into the lungs?"},{"Start":"05:34.240 ","End":"05:39.830","Text":"Yes, and then out of the second exhalation,"},{"Start":"05:39.830 ","End":"05:42.455","Text":"out of the anterior air sacs."},{"Start":"05:42.455 ","End":"05:46.640","Text":"To make things even more efficient, we have airflow,"},{"Start":"05:46.640 ","End":"05:50.120","Text":"which is perpendicular to the flow of blood and"},{"Start":"05:50.120 ","End":"05:54.869","Text":"this increases the efficiency of the gas exchange."}],"ID":30595}],"Thumbnail":null,"ID":294415},{"Name":"The Work of Breathing","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Lung Disease","Duration":"6m 3s","ChapterTopicVideoID":29034,"CourseChapterTopicPlaylistID":294416,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:08.850","Text":"Continuing our discussion of diseases that affect breathing and affect of gas exchange,"},{"Start":"00:08.850 ","End":"00:14.520","Text":"we\u0027ll now turn our attention to these obstructive diseases like asthma."},{"Start":"00:14.520 ","End":"00:17.670","Text":"Asthma is caused by inflammation"},{"Start":"00:17.670 ","End":"00:22.320","Text":"of the bronchioles that\u0027s triggered by various environmental factors,"},{"Start":"00:22.320 ","End":"00:24.720","Text":"let\u0027s say pollen or things of that sort."},{"Start":"00:24.720 ","End":"00:29.420","Text":"These can obstruct the pathways not letting air in."},{"Start":"00:29.420 ","End":"00:32.970","Text":"You know these people who have trouble breathing they\u0027ll,"},{"Start":"00:33.040 ","End":"00:37.700","Text":"the air simply doesn\u0027t go through very well."},{"Start":"00:37.700 ","End":"00:40.910","Text":"This can result from edema,"},{"Start":"00:40.910 ","End":"00:44.165","Text":"that\u0027s fluid accumulation in the area"},{"Start":"00:44.165 ","End":"00:49.550","Text":"around the bronchioles on the outside of the airways."},{"Start":"00:49.550 ","End":"00:54.755","Text":"It can be caused by smooth muscle spasms and the walls of the bronchioles."},{"Start":"00:54.755 ","End":"00:57.320","Text":"Or there can be increased mucus and there you hear"},{"Start":"00:57.320 ","End":"01:00.574","Text":"people coughing, increased mucus secretion."},{"Start":"01:00.574 ","End":"01:03.980","Text":"The airways can be damaged in that"},{"Start":"01:03.980 ","End":"01:07.970","Text":"the epithelia is damaged or some combination of these events."},{"Start":"01:07.970 ","End":"01:11.180","Text":"Of course, patients experienced increased occlusion,"},{"Start":"01:11.180 ","End":"01:15.350","Text":"that is that the air is obstructed and there can be"},{"Start":"01:15.350 ","End":"01:20.155","Text":"increased inflammation and that can also be somewhat painful."},{"Start":"01:20.155 ","End":"01:24.305","Text":"Those with obstructive diseases they have large volumes of trapped air"},{"Start":"01:24.305 ","End":"01:29.188","Text":"after they exhale and they breathe,"},{"Start":"01:29.188 ","End":"01:31.790","Text":"therefore, an exceedingly high lung"},{"Start":"01:31.790 ","End":"01:36.020","Text":"volume to compensate for the lack of airway recruitment."},{"Start":"01:36.020 ","End":"01:43.040","Text":"The lung, they hold a lot of air inside areas and air in"},{"Start":"01:43.040 ","End":"01:50.270","Text":"their lungs that in the attempt to compensate for the lack of exchange."},{"Start":"01:50.270 ","End":"01:51.560","Text":"Now, finally,"},{"Start":"01:51.560 ","End":"01:57.260","Text":"what we\u0027re going to do is look at dead space in the lungs."},{"Start":"01:57.260 ","End":"01:59.760","Text":"This is interesting things."},{"Start":"01:59.760 ","End":"02:05.540","Text":"The alveolar recruitment is"},{"Start":"02:05.540 ","End":"02:12.230","Text":"the process of opening airways that normally remain closed when cardiac output increases."},{"Start":"02:12.230 ","End":"02:14.075","Text":"What are we saying here?"},{"Start":"02:14.075 ","End":"02:18.365","Text":"It turns out that the pulmonary circulation pressure,"},{"Start":"02:18.365 ","End":"02:25.730","Text":"that is the pressure of the blood that\u0027s inside the lungs is rather low if you"},{"Start":"02:25.730 ","End":"02:29.405","Text":"compare it to the pressure that\u0027s in the rest of our system"},{"Start":"02:29.405 ","End":"02:33.835","Text":"and it\u0027s independent of the cardiac output."},{"Start":"02:33.835 ","End":"02:36.415","Text":"That\u0027s actually what you\u0027d really want,"},{"Start":"02:36.415 ","End":"02:41.015","Text":"that\u0027s because if the pressure changes too much in the bloodstream,"},{"Start":"02:41.015 ","End":"02:47.599","Text":"that would cause damage to these very thin capillaries and possibly to the alveoli."},{"Start":"02:47.599 ","End":"02:50.480","Text":"As the cardiac output increases,"},{"Start":"02:50.480 ","End":"02:52.100","Text":"like let\u0027s say when you start to run,"},{"Start":"02:52.100 ","End":"02:56.285","Text":"the number of capillaries and arteries that are perfused, that is,"},{"Start":"02:56.285 ","End":"03:01.790","Text":"that have blood going through them increases."},{"Start":"03:01.790 ","End":"03:05.450","Text":"It turns out here that there are"},{"Start":"03:05.450 ","End":"03:13.285","Text":"local control mechanisms that try to keep ventilation and perfusion matched."},{"Start":"03:13.285 ","End":"03:17.110","Text":"The blood vessels are not always in use,"},{"Start":"03:17.110 ","End":"03:19.555","Text":"but they\u0027re ready if needed."},{"Start":"03:19.555 ","End":"03:25.750","Text":"We see here is that there is local control that keeps the ventilation perfusion matched."},{"Start":"03:25.750 ","End":"03:29.590","Text":"A decreased pressure, oxygen pressure around"},{"Start":"03:29.590 ","End":"03:33.220","Text":"the under ventilated alveoli constricts these arterioles"},{"Start":"03:33.220 ","End":"03:37.120","Text":"diverting blood to better ventilated alveoli."},{"Start":"03:37.120 ","End":"03:40.720","Text":"If a particular alveoli are not well ventilated,"},{"Start":"03:40.720 ","End":"03:42.350","Text":"they don\u0027t have a lot of air in them,"},{"Start":"03:42.350 ","End":"03:47.065","Text":"then there is a control mechanism that diverts blood"},{"Start":"03:47.065 ","End":"03:52.855","Text":"to the capillaries of the alveoli that are better ventilated."},{"Start":"03:52.855 ","End":"03:58.364","Text":"But when more alveoli are recruited,"},{"Start":"03:58.364 ","End":"04:02.680","Text":"here you can see there\u0027s an alveoli now that has better,"},{"Start":"04:02.680 ","End":"04:04.090","Text":"more air in it,"},{"Start":"04:04.090 ","End":"04:08.545","Text":"then the blood will start to flow to there as well so"},{"Start":"04:08.545 ","End":"04:14.584","Text":"that it can respond to the demand for higher oxygen."},{"Start":"04:14.584 ","End":"04:22.300","Text":"There is a ventilation perfusion quotient."},{"Start":"04:22.300 ","End":"04:24.340","Text":"That\u0027s this V/Q,"},{"Start":"04:24.340 ","End":"04:27.910","Text":"a mismatch between the ventilation and perfusion,"},{"Start":"04:27.910 ","End":"04:33.985","Text":"which is denoted as a Q in the lungs and this mismatch can occur."},{"Start":"04:33.985 ","End":"04:38.880","Text":"Here\u0027s a normal situation where this V/Q ratio is about 0.8,"},{"Start":"04:38.880 ","End":"04:43.340","Text":"where the shunt perfusion isn\u0027t working properly,"},{"Start":"04:43.340 ","End":"04:47.825","Text":"the alveoli are smaller and we have wasted perfusion."},{"Start":"04:47.825 ","End":"04:51.020","Text":"That is, we\u0027ve got blood going"},{"Start":"04:51.020 ","End":"04:54.550","Text":"through capillaries but we don\u0027t have a good gas exchange."},{"Start":"04:54.550 ","End":"04:58.144","Text":"There can also be dead space ventilation."},{"Start":"04:58.144 ","End":"05:01.160","Text":"There too we have wasted ventilation."},{"Start":"05:01.160 ","End":"05:04.320","Text":"We have an pulmonary embolism."},{"Start":"05:04.420 ","End":"05:09.290","Text":"That is that the blood vessels are too large and can have"},{"Start":"05:09.290 ","End":"05:13.775","Text":"a very high volume to perfusion situation,"},{"Start":"05:13.775 ","End":"05:17.764","Text":"and there too we don\u0027t have good gas exchange."},{"Start":"05:17.764 ","End":"05:22.303","Text":"This dead space region"},{"Start":"05:22.303 ","End":"05:26.270","Text":"can be regions of broken down or blocked lung tissue that caused this,"},{"Start":"05:26.270 ","End":"05:28.715","Text":"for instance, this embolism as we mentioned."},{"Start":"05:28.715 ","End":"05:33.680","Text":"This reduces the surface area available for gas diffusion, and of course,"},{"Start":"05:33.680 ","End":"05:38.920","Text":"decreases the amount of oxygen in the blood and increases the CO_2 level."},{"Start":"05:38.920 ","End":"05:43.565","Text":"This dead space is created either when"},{"Start":"05:43.565 ","End":"05:49.400","Text":"no ventilation occurs or when the perfusion might be too high."},{"Start":"05:49.400 ","End":"05:57.365","Text":"This quotient of V to Q should be kept at a normal level,"},{"Start":"05:57.365 ","End":"06:02.130","Text":"otherwise, oxygenation doesn\u0027t work as well."}],"ID":30617},{"Watched":false,"Name":"Lung Resistance and Compliance","Duration":"7m 10s","ChapterTopicVideoID":29035,"CourseChapterTopicPlaylistID":294416,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.140 ","End":"00:05.204","Text":"I\u0027m glad you\u0027re back to continue our discussion about the work,"},{"Start":"00:05.204 ","End":"00:08.685","Text":"the energy that\u0027s required to breathe."},{"Start":"00:08.685 ","End":"00:12.690","Text":"Now, there are various diseases that you probably know about."},{"Start":"00:12.690 ","End":"00:20.100","Text":"For instance, emphysema is one of them that cause problems in gas exchange."},{"Start":"00:20.100 ","End":"00:25.200","Text":"We\u0027re going to be talking about lung resistance and compliance."},{"Start":"00:25.200 ","End":"00:34.860","Text":"That is how it either resist or be compliant with inflow and outflow of air."},{"Start":"00:34.860 ","End":"00:41.475","Text":"Pulmonary diseases reduce the rate of gas exchange into and out of the lungs, of course."},{"Start":"00:41.475 ","End":"00:46.760","Text":"We can see this in the various graphs that we have here on the right."},{"Start":"00:46.760 ","End":"00:48.605","Text":"In a normal graph,"},{"Start":"00:48.605 ","End":"00:52.630","Text":"we have the pressure."},{"Start":"00:52.630 ","End":"00:54.455","Text":"As the pressure goes up,"},{"Start":"00:54.455 ","End":"00:56.750","Text":"how the lung volume changes."},{"Start":"00:56.750 ","End":"01:00.140","Text":"That\u0027ll be something having to do with the elasticity of the lung."},{"Start":"01:00.140 ","End":"01:03.785","Text":"In emphysema, as the pulmonary pressure goes up,"},{"Start":"01:03.785 ","End":"01:05.885","Text":"the lung will get too big."},{"Start":"01:05.885 ","End":"01:09.795","Text":"In fibrosis, it won\u0027t be big enough."},{"Start":"01:09.795 ","End":"01:12.170","Text":"We\u0027re going to be looking at compliance,"},{"Start":"01:12.170 ","End":"01:15.740","Text":"that is how elastic the lung is, and secondly,"},{"Start":"01:15.740 ","End":"01:18.890","Text":"the resistance of how much obstruction exists in"},{"Start":"01:18.890 ","End":"01:23.610","Text":"the airways to keep the lungs from getting large."},{"Start":"01:23.630 ","End":"01:26.365","Text":"Both of these things, of course,"},{"Start":"01:26.365 ","End":"01:29.710","Text":"can dramatically alter the breathing."},{"Start":"01:29.710 ","End":"01:34.195","Text":"How large the lung is and whether the air can get through,"},{"Start":"01:34.195 ","End":"01:38.885","Text":"and that will affect the gas exchange, of course."},{"Start":"01:38.885 ","End":"01:42.955","Text":"Let\u0027s look first at restrictive diseases."},{"Start":"01:42.955 ","End":"01:50.305","Text":"In restrictive diseases, the airways let less air through."},{"Start":"01:50.305 ","End":"01:53.230","Text":"They can become stiff or fibrotic,"},{"Start":"01:53.230 ","End":"01:58.820","Text":"have these fibers in them so that the lung tissue can\u0027t bend or move."},{"Start":"01:58.820 ","End":"02:04.555","Text":"Here for instance, we have the normal lungs where in 1 second, of course,"},{"Start":"02:04.555 ","End":"02:11.840","Text":"how much the volume increases upon the volume exhaled in this graph."},{"Start":"02:11.840 ","End":"02:16.580","Text":"This is 1 second then how much what the total volume is going to be in the normal lobe."},{"Start":"02:16.580 ","End":"02:20.060","Text":"In the restrictive disease, in 1 second,"},{"Start":"02:20.060 ","End":"02:24.255","Text":"we\u0027re going to have less volume coming out, of course,"},{"Start":"02:24.255 ","End":"02:33.950","Text":"and the total volume is going to take more time to get out."},{"Start":"02:33.950 ","End":"02:39.320","Text":"In these cases, the intrapleural pressure is going to be more positive."},{"Start":"02:39.320 ","End":"02:44.855","Text":"It\u0027s going to require more work to get to that point."},{"Start":"02:44.855 ","End":"02:51.425","Text":"The airways also can collapse upon exhalation and that can trap air in the lungs."},{"Start":"02:51.425 ","End":"02:52.820","Text":"Those are not good things."},{"Start":"02:52.820 ","End":"02:55.340","Text":"This total volume that we talked about,"},{"Start":"02:55.340 ","End":"02:59.054","Text":"the functional vital capacity, FVC,"},{"Start":"02:59.054 ","End":"03:05.645","Text":"will be lower and the time it takes to exhale most of the air more prolonged, of course."},{"Start":"03:05.645 ","End":"03:09.500","Text":"A patient who is suffering from these diseases cannot exhale"},{"Start":"03:09.500 ","End":"03:15.060","Text":"the normal amount of air and the gas exchange won\u0027t be as good."},{"Start":"03:15.110 ","End":"03:21.990","Text":"Let\u0027s look and see what the lung might look like in these pulmonary fibrosis."},{"Start":"03:21.990 ","End":"03:26.420","Text":"The lung disease that occurs when the tissues become damaged or scarred."},{"Start":"03:26.420 ","End":"03:30.530","Text":"Here you can see normal lungs, but after scarring,"},{"Start":"03:30.530 ","End":"03:34.010","Text":"the alveoli might not be normal and not have"},{"Start":"03:34.010 ","End":"03:41.420","Text":"the same structure and the same amount of surface area to exchange gases."},{"Start":"03:41.420 ","End":"03:45.455","Text":"The replacement of normal lung with the scar tissue causes"},{"Start":"03:45.455 ","End":"03:50.065","Text":"irreversible decrease in oxygen diffusion capacity."},{"Start":"03:50.065 ","End":"03:55.340","Text":"There\u0027s less ability of oxygen to get into the blood,"},{"Start":"03:55.340 ","End":"03:57.335","Text":"as you can see a larger arrow in"},{"Start":"03:57.335 ","End":"04:02.885","Text":"the normal situation than in the pulmonary fibrosis situation."},{"Start":"04:02.885 ","End":"04:06.515","Text":"That can be caused by various environmental pollutants."},{"Start":"04:06.515 ","End":"04:09.395","Text":"Sometimes there are various medicines that could cause this."},{"Start":"04:09.395 ","End":"04:16.205","Text":"Various connective tissue diseases and something called interstitial lung disease."},{"Start":"04:16.205 ","End":"04:22.955","Text":"Unfortunately, there\u0027s no cure for these things and the treatment is also rather limited."},{"Start":"04:22.955 ","End":"04:26.420","Text":"I mentioned earlier that in newborn babies,"},{"Start":"04:26.420 ","End":"04:30.055","Text":"there is an issue of the surfactants."},{"Start":"04:30.055 ","End":"04:33.890","Text":"There is newborn respiratory distress syndrome,"},{"Start":"04:33.890 ","End":"04:38.975","Text":"NRDS, when the baby\u0027s lungs are not fully developed, and therefore,"},{"Start":"04:38.975 ","End":"04:44.220","Text":"they have their alveoli collapse because of the surfactant issue,"},{"Start":"04:44.220 ","End":"04:48.100","Text":"and that can cause breathing difficulties."},{"Start":"04:48.100 ","End":"04:50.405","Text":"The treatment of that,"},{"Start":"04:50.405 ","End":"04:51.785","Text":"as we mentioned earlier,"},{"Start":"04:51.785 ","End":"05:01.470","Text":"also is done by giving some extra oxygen and sometimes surfactant can be added as well."},{"Start":"05:01.780 ","End":"05:07.085","Text":"Now, there can also be obstructive diseases."},{"Start":"05:07.085 ","End":"05:08.780","Text":"What are obstructive diseases?"},{"Start":"05:08.780 ","End":"05:14.644","Text":"That\u0027s the type of lung disease that occurs when there are blockages in the airways."},{"Start":"05:14.644 ","End":"05:19.985","Text":"What we\u0027ve seen until now are these restrictive diseases."},{"Start":"05:19.985 ","End":"05:25.043","Text":"The obstructive diseases will be such that it takes longer,"},{"Start":"05:25.043 ","End":"05:33.440","Text":"you can see the shape of this curve for the volume to get to what it normally should be."},{"Start":"05:33.440 ","End":"05:38.255","Text":"It takes longer because of the blockages and that of course,"},{"Start":"05:38.255 ","End":"05:43.580","Text":"damages the lungs and causes the airways to narrow, causing breathing difficulties."},{"Start":"05:43.580 ","End":"05:47.765","Text":"This can result in smaller bronchi,"},{"Start":"05:47.765 ","End":"05:55.115","Text":"larger bronchioles because of the excessive contraction of the smooth muscle."},{"Start":"05:55.115 ","End":"05:59.520","Text":"Emphysema is one of these obstructive diseases."},{"Start":"05:59.520 ","End":"06:05.225","Text":"Tobacco smoking is the number one factor of this disease."},{"Start":"06:05.225 ","End":"06:08.345","Text":"Please don\u0027t smoke, this is why."},{"Start":"06:08.345 ","End":"06:13.900","Text":"You can see the inside of these lungs becomes blackened."},{"Start":"06:13.900 ","End":"06:19.280","Text":"Yes, you get carbon deposits and tar on the inside"},{"Start":"06:19.280 ","End":"06:24.725","Text":"of the lung that keep the lungs from exchanging gases."},{"Start":"06:24.725 ","End":"06:27.484","Text":"Also there can be build-up inside"},{"Start":"06:27.484 ","End":"06:32.270","Text":"the bronchioles that restrict the amount of air going through,"},{"Start":"06:32.270 ","End":"06:36.230","Text":"and the walls of the alveoli become destroyed,"},{"Start":"06:36.230 ","End":"06:38.360","Text":"decreasing the surface area as we said."},{"Start":"06:38.360 ","End":"06:41.765","Text":"The overall compliance of the lung is increased."},{"Start":"06:41.765 ","End":"06:44.000","Text":"Because the alveolar walls are damaged,"},{"Start":"06:44.000 ","End":"06:47.795","Text":"the lung elasticity becomes less good,"},{"Start":"06:47.795 ","End":"06:52.550","Text":"decreases due to the loss of elastic fibers."},{"Start":"06:52.550 ","End":"06:57.595","Text":"Therefore, more air is trapped in the lungs at the end of exhalation."},{"Start":"06:57.595 ","End":"06:59.375","Text":"At the end of exhalation,"},{"Start":"06:59.375 ","End":"07:10.080","Text":"the alveoli don\u0027t contract sufficiently and there is less ability to oxygenate the blood."}],"ID":30618},{"Watched":false,"Name":"Surface Tension in the Lungs","Duration":"4m 54s","ChapterTopicVideoID":29036,"CourseChapterTopicPlaylistID":294416,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.105","Text":"Let\u0027s continue our discussion of breathing."},{"Start":"00:03.105 ","End":"00:08.640","Text":"An aspect that you may not have thought about that has to do with breathing"},{"Start":"00:08.640 ","End":"00:14.235","Text":"which turns out to be very important is the alveolar surface tension,"},{"Start":"00:14.235 ","End":"00:17.850","Text":"surface tension that there is inside the alveoli."},{"Start":"00:17.850 ","End":"00:25.380","Text":"You\u0027ll remember that surface tension is what keeps a water droplet together."},{"Start":"00:25.380 ","End":"00:29.865","Text":"It\u0027s the surface, that\u0027s the air,"},{"Start":"00:29.865 ","End":"00:34.430","Text":"water interface, that it causes some tension."},{"Start":"00:34.430 ","End":"00:41.060","Text":"It\u0027s the way the molecules of water organize on the surface of the water droplets,"},{"Start":"00:41.060 ","End":"00:46.294","Text":"and that causes a certain surface tension,"},{"Start":"00:46.294 ","End":"00:50.795","Text":"a structural thing inside the alveoli."},{"Start":"00:50.795 ","End":"00:53.435","Text":"That is very important."},{"Start":"00:53.435 ","End":"00:59.810","Text":"It will turn out in keeping the alveoli structure open so they don\u0027t collapse."},{"Start":"00:59.810 ","End":"01:07.025","Text":"There is something called the Law of Laplace in which the air pressure in the alveoli"},{"Start":"01:07.025 ","End":"01:11.030","Text":"is directly proportional to the surface tension that we"},{"Start":"01:11.030 ","End":"01:15.550","Text":"call t. The pressure is proportional."},{"Start":"01:15.550 ","End":"01:18.880","Text":"The pressure in the alveoli which is going to keep them"},{"Start":"01:18.880 ","End":"01:24.740","Text":"open is directly proportional to this surface tension that\u0027s inside,"},{"Start":"01:24.740 ","End":"01:26.780","Text":"but it\u0027s inversely proportional,"},{"Start":"01:26.780 ","End":"01:31.595","Text":"that is on the bottom to the radius of the alveoli."},{"Start":"01:31.595 ","End":"01:36.770","Text":"The larger the radius of the alveoli,"},{"Start":"01:36.770 ","End":"01:41.510","Text":"the larger the alveoli the smaller the pressure will be."},{"Start":"01:41.510 ","End":"01:43.385","Text":"Let\u0027s look at that."},{"Start":"01:43.385 ","End":"01:46.805","Text":"The pressure in a smaller alveolus,"},{"Start":"01:46.805 ","End":"01:48.785","Text":"like we have over here,"},{"Start":"01:48.785 ","End":"01:55.820","Text":"the pressure would be greater than in the large alveolus if the surface tension is the"},{"Start":"01:55.820 ","End":"02:02.645","Text":"same in both as you can see over here because the radius is double."},{"Start":"02:02.645 ","End":"02:06.310","Text":"In this example, it\u0027s larger."},{"Start":"02:06.310 ","End":"02:10.340","Text":"Therefore, small alveoli would be at"},{"Start":"02:10.340 ","End":"02:15.395","Text":"great risk of collapsing because the pressure inside is lower."},{"Start":"02:15.395 ","End":"02:18.200","Text":"Of course, if the alveoli collapse,"},{"Start":"02:18.200 ","End":"02:21.115","Text":"then they\u0027re no longer useful."},{"Start":"02:21.115 ","End":"02:27.875","Text":"To counter that, the body makes something called a pulmonary surfactant."},{"Start":"02:27.875 ","End":"02:29.150","Text":"What\u0027s a surfactant?"},{"Start":"02:29.150 ","End":"02:36.170","Text":"A surfactant is a surface active complex that is going to change the surface tension."},{"Start":"02:36.170 ","End":"02:39.680","Text":"It\u0027s made up of phospholipids and proteins and this reduces"},{"Start":"02:39.680 ","End":"02:45.395","Text":"the surface tension between the alveoli tissue and the air found within the alveoli."},{"Start":"02:45.395 ","End":"02:50.780","Text":"It changes the surface tension and it reduces the tendency of the alveoli to"},{"Start":"02:50.780 ","End":"02:56.854","Text":"collapse and the effort needed to inflate those alveoli."},{"Start":"02:56.854 ","End":"03:00.380","Text":"That\u0027s extremely important for preventing the collapse of"},{"Start":"03:00.380 ","End":"03:04.735","Text":"this small alveoli relative to the large alveoli."},{"Start":"03:04.735 ","End":"03:07.640","Text":"As we mentioned, without surfactant,"},{"Start":"03:07.640 ","End":"03:11.450","Text":"the pressures would be different in"},{"Start":"03:11.450 ","End":"03:17.449","Text":"a small and large alveoli and the small ones would be more likely to collapse."},{"Start":"03:17.449 ","End":"03:22.055","Text":"On the other hand, with surfactant that changes the surface pressure,"},{"Start":"03:22.055 ","End":"03:24.890","Text":"1 would have less surface tension."},{"Start":"03:24.890 ","End":"03:28.120","Text":"The smaller one would have less surface tension that\u0027s"},{"Start":"03:28.120 ","End":"03:31.655","Text":"more surfactant than those smaller alveoli,"},{"Start":"03:31.655 ","End":"03:35.540","Text":"and that can be adjusted such that"},{"Start":"03:35.540 ","End":"03:41.610","Text":"both alveoli 1 and 2 in this example have equal pressure because of that surfactant,"},{"Start":"03:41.610 ","End":"03:48.765","Text":"and therefore 1 will inflate faster rate than 2 until they\u0027ll equal in size."},{"Start":"03:48.765 ","End":"03:55.230","Text":"That will prevent the smaller one from collapsing."},{"Start":"03:56.060 ","End":"04:02.335","Text":"If sub types could go wrong in something called respiratory distress syndrome,"},{"Start":"04:02.335 ","End":"04:05.315","Text":"and that happens in babies that are born prematurely."},{"Start":"04:05.315 ","End":"04:07.535","Text":"You probably know that that\u0027s"},{"Start":"04:07.535 ","End":"04:11.585","Text":"the big danger that the lungs they say are not fully developed."},{"Start":"04:11.585 ","End":"04:12.995","Text":"That\u0027s what they\u0027re talking about."},{"Start":"04:12.995 ","End":"04:17.360","Text":"They\u0027re talking about the ability of surfactant to"},{"Start":"04:17.360 ","End":"04:22.280","Text":"move into various needed areas of lungs, the smaller alveoli."},{"Start":"04:22.280 ","End":"04:28.440","Text":"Babies born prematurely don\u0027t produce enough of this surfactant, and therefore,"},{"Start":"04:28.440 ","End":"04:32.435","Text":"they demand more effort to inflate their lungs and they may not"},{"Start":"04:32.435 ","End":"04:37.070","Text":"get sufficient amount of air into their lungs."},{"Start":"04:37.070 ","End":"04:42.980","Text":"This can be corrected using higher concentrations of oxygen."},{"Start":"04:42.980 ","End":"04:45.230","Text":"That\u0027s often what\u0027s done to these premature babies,"},{"Start":"04:45.230 ","End":"04:51.090","Text":"is give them a higher percentage of oxygen in the air that they breathe."}],"ID":30619},{"Watched":false,"Name":"Anatomical Shunts of Capillaries in the Lung","Duration":"4m 19s","ChapterTopicVideoID":29037,"CourseChapterTopicPlaylistID":294416,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.540","Text":"It\u0027s good that you\u0027re back to continue our discussion of the dead space."},{"Start":"00:06.540 ","End":"00:15.225","Text":"You\u0027ll remember the ventilation versus perfusion mismatch."},{"Start":"00:15.225 ","End":"00:20.534","Text":"The V over Q ventilation perfusion mismatch."},{"Start":"00:20.534 ","End":"00:28.860","Text":"We have to be ventilating the alveoli that is getting air into the alveoli and"},{"Start":"00:28.860 ","End":"00:32.460","Text":"that has to be matched somehow or other with"},{"Start":"00:32.460 ","End":"00:37.450","Text":"the perfusion that is how much blood is going past."},{"Start":"00:37.450 ","End":"00:40.085","Text":"In normal situation,"},{"Start":"00:40.085 ","End":"00:44.675","Text":"now the blood goes through the alveoli and"},{"Start":"00:44.675 ","End":"00:49.805","Text":"is oxygenated as it goes out and the carbon dioxide leaves."},{"Start":"00:49.805 ","End":"00:59.975","Text":"But sometimes there can be capillaries that bypass the alveoli."},{"Start":"00:59.975 ","End":"01:03.440","Text":"There\u0027s non-oxygenated blood which might"},{"Start":"01:03.440 ","End":"01:07.460","Text":"join up with the other blood which has been oxygenated,"},{"Start":"01:07.460 ","End":"01:10.190","Text":"lowering the amount of oxygen in the blood."},{"Start":"01:10.190 ","End":"01:14.780","Text":"In that case, blood might be going from the right side to the left side of"},{"Start":"01:14.780 ","End":"01:19.615","Text":"the heart without ever traversing pulmonary capillaries."},{"Start":"01:19.615 ","End":"01:21.335","Text":"Therefore, there won\u0027t be"},{"Start":"01:21.335 ","End":"01:25.580","Text":"any alveolar gas exchange lowering the amount of oxygen in the blood,"},{"Start":"01:25.580 ","End":"01:28.910","Text":"and that is certainly not a good thing."},{"Start":"01:28.910 ","End":"01:34.370","Text":"That can occur when the blood supply to the lungs via the pulmonary arteries is"},{"Start":"01:34.370 ","End":"01:41.330","Text":"returned via the pulmonary veins without going through these pulmonary capillaries."},{"Start":"01:41.330 ","End":"01:43.100","Text":"Of course, that\u0027ll be only some of them."},{"Start":"01:43.100 ","End":"01:44.750","Text":"If all of them did that,"},{"Start":"01:44.750 ","End":"01:47.150","Text":"then the person would be dead."},{"Start":"01:47.150 ","End":"01:53.899","Text":"So the ventilation in this particular area is unaffected in this disease,"},{"Start":"01:53.899 ","End":"01:57.545","Text":"but the blood won\u0027t be oxygenated."},{"Start":"01:57.545 ","End":"02:02.140","Text":"So the ventilation, that is the amount of oxygen which"},{"Start":"02:02.140 ","End":"02:07.385","Text":"gets early mountain air and it gets into the alveoli is about the same,"},{"Start":"02:07.385 ","End":"02:12.110","Text":"but the blood flow is not normal and that of course,"},{"Start":"02:12.110 ","End":"02:18.350","Text":"will affect this, the Q ratio."},{"Start":"02:18.350 ","End":"02:20.405","Text":"The rate of gas exchange,"},{"Start":"02:20.405 ","End":"02:22.895","Text":"in this case, is reduced."},{"Start":"02:22.895 ","End":"02:25.745","Text":"Looking at this physiological shunt,"},{"Start":"02:25.745 ","End":"02:28.505","Text":"this can happen sometimes if,"},{"Start":"02:28.505 ","End":"02:32.495","Text":"let\u0027s say we get some alveoli which are filled with fluid,"},{"Start":"02:32.495 ","End":"02:35.465","Text":"so there are alveoli there."},{"Start":"02:35.465 ","End":"02:42.485","Text":"But they can\u0027t exchange gases because they\u0027ve filled with fluid and this can happen,"},{"Start":"02:42.485 ","End":"02:46.745","Text":"let\u0027s say if there\u0027s an infection or there\u0027s edema in the lung that is there,"},{"Start":"02:46.745 ","End":"02:48.980","Text":"is there some bleeding in the lung."},{"Start":"02:48.980 ","End":"02:51.560","Text":"Let\u0027s say there is pneumonia for instance,"},{"Start":"02:51.560 ","End":"02:52.595","Text":"which is causing this."},{"Start":"02:52.595 ","End":"02:54.785","Text":"That would be an infection in the lung."},{"Start":"02:54.785 ","End":"03:02.705","Text":"In that case, some of the capillaries would simply shunt around those areas."},{"Start":"03:02.705 ","End":"03:07.370","Text":"This intrapulmonary shunting would occur and that decreases"},{"Start":"03:07.370 ","End":"03:14.990","Text":"the ventilation as well because the alveoli are full of liquid,"},{"Start":"03:14.990 ","End":"03:19.025","Text":"but it does not affect blood perfusion."},{"Start":"03:19.025 ","End":"03:23.570","Text":"That again, would cause this mismatch between the 2."},{"Start":"03:23.570 ","End":"03:28.355","Text":"The lung, however, can compensate for these shunts sometimes."},{"Start":"03:28.355 ","End":"03:33.035","Text":"So that if the ventilation is greater than the perfusion,"},{"Start":"03:33.035 ","End":"03:35.180","Text":"as we saw earlier, that is,"},{"Start":"03:35.180 ","End":"03:40.080","Text":"the ventilation would be normal,"},{"Start":"03:40.080 ","End":"03:44.270","Text":"but the perfusion is not normal because of the shunting,"},{"Start":"03:44.270 ","End":"03:49.480","Text":"then the arterioles might dilate and the bronchioles constrict."},{"Start":"03:49.480 ","End":"03:54.665","Text":"This would increase the perfusion and reduce ventilation in order to compensate."},{"Start":"03:54.665 ","End":"03:59.105","Text":"However, if ventilation is less than perfusion,"},{"Start":"03:59.105 ","End":"04:01.505","Text":"as we saw in this example,"},{"Start":"04:01.505 ","End":"04:04.220","Text":"then the arterioles can constrict,"},{"Start":"04:04.220 ","End":"04:08.830","Text":"and the bronchioles dilate to correct the imbalance."},{"Start":"04:08.830 ","End":"04:12.765","Text":"Yes, the arterioles can constrict"},{"Start":"04:12.765 ","End":"04:18.270","Text":"but the bronchioles dilate so that you can get more air in."}],"ID":30620},{"Watched":false,"Name":"Breathing Requires Energy","Duration":"7m 12s","ChapterTopicVideoID":29038,"CourseChapterTopicPlaylistID":294416,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.675","Text":"I\u0027m glad you\u0027re back to discuss the subject of breathing."},{"Start":"00:03.675 ","End":"00:06.810","Text":"Until now, we\u0027ve been discussing gas exchange,"},{"Start":"00:06.810 ","End":"00:10.890","Text":"which of course is the most important thing in breathing and also some of"},{"Start":"00:10.890 ","End":"00:15.075","Text":"the mechanics that had to do with the structures of say,"},{"Start":"00:15.075 ","End":"00:20.265","Text":"gills or lungs or gas exchange, even across skin."},{"Start":"00:20.265 ","End":"00:27.735","Text":"But we have not really considered how much energy is required to breathe at all."},{"Start":"00:27.735 ","End":"00:31.075","Text":"Let\u0027s call that the work of breathing,"},{"Start":"00:31.075 ","End":"00:35.100","Text":"the energy that\u0027s used by the muscles for respiration."},{"Start":"00:35.100 ","End":"00:39.810","Text":"Here we can see an elk who is breathing out, is actually calling."},{"Start":"00:39.810 ","End":"00:44.215","Text":"That of course, is going to require some energy,"},{"Start":"00:44.215 ","End":"00:49.190","Text":"so how much energy is going to be expended in the process of breathing."},{"Start":"00:49.190 ","End":"00:52.310","Text":"We\u0027ll find out that this is very"},{"Start":"00:52.310 ","End":"00:58.330","Text":"important when it comes to how well the lungs are working."},{"Start":"00:58.330 ","End":"01:01.455","Text":"Again, the work of breathing,"},{"Start":"01:01.455 ","End":"01:03.715","Text":"let\u0027s call that WOB,"},{"Start":"01:03.715 ","End":"01:08.345","Text":"is the energy that\u0027s used by the muscles for"},{"Start":"01:08.345 ","End":"01:13.100","Text":"respiration and it can be"},{"Start":"01:13.100 ","End":"01:15.500","Text":"calculated in terms of the pulmonary pressure"},{"Start":"01:15.500 ","End":"01:18.700","Text":"multiplied by the change in pulmonary volume."},{"Start":"01:18.700 ","End":"01:27.543","Text":"So pressure times volume."},{"Start":"01:27.543 ","End":"01:33.440","Text":"Or you can also measure it in terms of how much oxygen is required to do this breathing."},{"Start":"01:33.440 ","End":"01:42.260","Text":"Of course, there are different factors that the breathing has to deal with."},{"Start":"01:42.260 ","End":"01:46.940","Text":"For instance, there are the elastic forces that are in alveoli,"},{"Start":"01:46.940 ","End":"01:48.523","Text":"they have to be expanded."},{"Start":"01:48.523 ","End":"01:53.405","Text":"If you\u0027re blowing into balloon that cost some energy during inspiration."},{"Start":"01:53.405 ","End":"01:55.985","Text":"There\u0027s the effort that has to be used to"},{"Start":"01:55.985 ","End":"02:00.574","Text":"move the air past restrictive forces during inspiration."},{"Start":"02:00.574 ","End":"02:08.105","Text":"That\u0027ll be the friction that the air encounters when it enters all these small passages."},{"Start":"02:08.105 ","End":"02:14.020","Text":"Of course, there may be energy required to force the air out during expiration."},{"Start":"02:14.020 ","End":"02:18.250","Text":"All those would contribute to the work of breathing,"},{"Start":"02:18.250 ","End":"02:21.609","Text":"and in a normal resting state interestingly,"},{"Start":"02:21.609 ","End":"02:27.000","Text":"this constitutes about 5 percent of the total body oxygen consumption."},{"Start":"02:27.000 ","End":"02:32.350","Text":"We spend about 5 percent of the oxygen consumption just"},{"Start":"02:32.350 ","End":"02:37.910","Text":"in getting the oxygen in and the carbon dioxide out."},{"Start":"02:37.910 ","End":"02:42.130","Text":"To look at this in a more quantitative way,"},{"Start":"02:42.130 ","End":"02:47.135","Text":"we\u0027ll discuss something called the respiratory rate."},{"Start":"02:47.135 ","End":"02:51.740","Text":"We\u0027ll look at something called alveolar ventilation."},{"Start":"02:51.740 ","End":"02:56.420","Text":"So how much air is getting in and out of the alveoli."},{"Start":"02:56.420 ","End":"03:01.955","Text":"The respiratory rate is going to be the number of breaths taken per minute,"},{"Start":"03:01.955 ","End":"03:03.740","Text":"so how fast we\u0027re breathing."},{"Start":"03:03.740 ","End":"03:12.995","Text":"Yeah, that\u0027ll be normally about 12-15 breaths per minute when we\u0027re resting."},{"Start":"03:12.995 ","End":"03:15.305","Text":"That can be measured."},{"Start":"03:15.305 ","End":"03:18.665","Text":"The alveolar ventilation, on the other hand,"},{"Start":"03:18.665 ","End":"03:25.580","Text":"is going to be how much air moves in and out of the alveoli."},{"Start":"03:25.580 ","End":"03:30.055","Text":"Now, there\u0027s a relationship between these 2 things, of course."},{"Start":"03:30.055 ","End":"03:35.764","Text":"There are 2 because there are 2 ways to keep the alveolar ventilation constant,"},{"Start":"03:35.764 ","End":"03:39.260","Text":"how much air is getting into the alveoli."},{"Start":"03:39.260 ","End":"03:45.860","Text":"Either, we can increase the respiratory rate while decreasing the tidal volume of air,"},{"Start":"03:45.860 ","End":"03:49.565","Text":"that is how much air is getting in per breath but"},{"Start":"03:49.565 ","End":"03:53.750","Text":"increase how quickly we breathe back-and-forth,"},{"Start":"03:53.750 ","End":"03:56.185","Text":"back-and-forth, how many breaths there are."},{"Start":"03:56.185 ","End":"03:58.400","Text":"We can see this going up here,"},{"Start":"03:58.400 ","End":"03:59.900","Text":"the number of breaths going up,"},{"Start":"03:59.900 ","End":"04:03.245","Text":"but we can also decrease the respiratory rate while"},{"Start":"04:03.245 ","End":"04:06.650","Text":"increasing the tidal volume per breath."},{"Start":"04:06.650 ","End":"04:10.715","Text":"What does that mean? That means we\u0027re breathing more slowly,"},{"Start":"04:10.715 ","End":"04:17.690","Text":"fewer breaths, but we\u0027re increasing the volume of each breath."},{"Start":"04:17.690 ","End":"04:20.780","Text":"That will do the work in the same way."},{"Start":"04:20.780 ","End":"04:27.290","Text":"Here you can see that in this treadmill velocity where we require more and more oxygen,"},{"Start":"04:27.290 ","End":"04:29.900","Text":"what we can be doing in the bottom curve"},{"Start":"04:29.900 ","End":"04:33.800","Text":"is taking deeper and deeper breaths and the upper one,"},{"Start":"04:33.800 ","End":"04:37.300","Text":"what we\u0027re doing is we\u0027re taking more breaths."},{"Start":"04:37.300 ","End":"04:39.645","Text":"Of course, in both,"},{"Start":"04:39.645 ","End":"04:42.530","Text":"the ventilations of the alveoli remain the same,"},{"Start":"04:42.530 ","End":"04:44.863","Text":"the amount of air that\u0027s going in and out of them,"},{"Start":"04:44.863 ","End":"04:47.150","Text":"but the type of work that\u0027s required to do"},{"Start":"04:47.150 ","End":"04:51.055","Text":"these 2 different things can be quite different."},{"Start":"04:51.055 ","End":"04:54.570","Text":"Therefore the energy spent can be different."},{"Start":"04:54.570 ","End":"04:58.730","Text":"Both the tidal volume and respiratory rate are"},{"Start":"04:58.730 ","End":"05:04.085","Text":"necessarily tightly regulated when the oxygen demand increases,"},{"Start":"05:04.085 ","End":"05:06.895","Text":"like when we\u0027re running."},{"Start":"05:06.895 ","End":"05:11.650","Text":"There are going to be 2 types of work conducting during respiration."},{"Start":"05:11.650 ","End":"05:14.005","Text":"There is flow resistive,"},{"Start":"05:14.005 ","End":"05:17.860","Text":"that is the work of the alveoli and the tissues in"},{"Start":"05:17.860 ","End":"05:21.975","Text":"the lung and there will be elastic work,"},{"Start":"05:21.975 ","End":"05:24.730","Text":"that\u0027s the work of the intercostal muscles,"},{"Start":"05:24.730 ","End":"05:26.545","Text":"the chest wall and the diaphragm."},{"Start":"05:26.545 ","End":"05:28.945","Text":"So 2 different things are going on."},{"Start":"05:28.945 ","End":"05:37.480","Text":"We\u0027ve got what is necessary to get the air past the small areas in the lungs,"},{"Start":"05:37.480 ","End":"05:40.720","Text":"the alveoli and the various tissues of the lung and of course,"},{"Start":"05:40.720 ","End":"05:46.880","Text":"moving the muscles up and down the chest wall and moving the diaphragm up and down."},{"Start":"05:46.880 ","End":"05:49.395","Text":"Increasing the respiration rate,"},{"Start":"05:49.395 ","End":"05:52.065","Text":"increases the flow-resistive work,"},{"Start":"05:52.065 ","End":"05:54.325","Text":"this is top part of the airways,"},{"Start":"05:54.325 ","End":"05:55.869","Text":"and at the same time,"},{"Start":"05:55.869 ","End":"05:58.930","Text":"decreases the elastic work of the muscles."},{"Start":"05:58.930 ","End":"06:03.420","Text":"Increasing respiration is going"},{"Start":"06:03.420 ","End":"06:07.120","Text":"to increase the flow-resistive work and decrease the elastic work."},{"Start":"06:07.120 ","End":"06:09.169","Text":"Decreasing the respiratory rate,"},{"Start":"06:09.169 ","End":"06:10.959","Text":"that\u0027s breathing more slowly,"},{"Start":"06:10.959 ","End":"06:14.330","Text":"reverses the type of work required."},{"Start":"06:14.900 ","End":"06:17.610","Text":"Now, let\u0027s look,"},{"Start":"06:17.610 ","End":"06:20.310","Text":"for instance, at the flow-resistive."},{"Start":"06:20.310 ","End":"06:22.690","Text":"It\u0027s required to move air through"},{"Start":"06:22.690 ","End":"06:26.690","Text":"the airways against the resistance of the airways as we said."},{"Start":"06:26.690 ","End":"06:28.596","Text":"There can be disease,"},{"Start":"06:28.596 ","End":"06:30.490","Text":"Chronic Obstructive Pulmonary Diseases,"},{"Start":"06:30.490 ","End":"06:36.334","Text":"COPD, and that would increase the elastic work that\u0027s necessary."},{"Start":"06:36.334 ","End":"06:40.610","Text":"The elastic work is"},{"Start":"06:40.610 ","End":"06:44.930","Text":"required to counter the elastic recoil like a balloon that\u0027s blowing up"},{"Start":"06:44.930 ","End":"06:48.560","Text":"during inspiration and it displaces"},{"Start":"06:48.560 ","End":"06:53.135","Text":"the chest wall outward while we\u0027re breathing in and the abdominal organs downward,"},{"Start":"06:53.135 ","End":"06:55.565","Text":"that\u0027s the diaphragm going down."},{"Start":"06:55.565 ","End":"07:04.520","Text":"In a disease such as pulmonary fibrosis where the elasticity becomes less good,"},{"Start":"07:04.520 ","End":"07:06.890","Text":"of all these various organs,"},{"Start":"07:06.890 ","End":"07:08.090","Text":"that will of course,"},{"Start":"07:08.090 ","End":"07:12.750","Text":"increase the elastic work that\u0027s necessary."}],"ID":30621}],"Thumbnail":null,"ID":294416},{"Name":"Transport of Gases in Human Bodily Fluids","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Bicarbonate Buffer System and Carbon Monoxide Poisoning","Duration":"4m 40s","ChapterTopicVideoID":29026,"CourseChapterTopicPlaylistID":294417,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.339","Text":"Welcome back to the 3rd video"},{"Start":"00:05.339 ","End":"00:09.750","Text":"that deals with the transport of oxygen via the red blood cells,"},{"Start":"00:09.750 ","End":"00:13.140","Text":"and we\u0027ve been discussing the bicarbonate buffer system."},{"Start":"00:13.140 ","End":"00:16.230","Text":"Let\u0027s look at this in a little bit more detail."},{"Start":"00:16.230 ","End":"00:21.975","Text":"We\u0027ve discussed the previous video about how in the red blood cells,"},{"Start":"00:21.975 ","End":"00:26.445","Text":"the carbon dioxide is absorbed into the cells,"},{"Start":"00:26.445 ","End":"00:33.290","Text":"and how it is then turned into carbonic acid,"},{"Start":"00:33.290 ","End":"00:39.734","Text":"which then goes into a bicarbonate ion."},{"Start":"00:39.734 ","End":"00:43.700","Text":"We have this movement between carbonic acid and bicarbonate ion,"},{"Start":"00:43.700 ","End":"00:51.095","Text":"which changes the pH either down if we\u0027re going to carbonic acid or up of course,"},{"Start":"00:51.095 ","End":"00:54.085","Text":"if we\u0027re going towards the bicarbonate."},{"Start":"00:54.085 ","End":"00:56.315","Text":"It\u0027s very important though,"},{"Start":"00:56.315 ","End":"01:04.145","Text":"that this blood really stay neutral around pH 7 and the system here"},{"Start":"01:04.145 ","End":"01:08.870","Text":"enables the soaked up carbon dioxide into the blood to keep"},{"Start":"01:08.870 ","End":"01:14.470","Text":"the pH quite stable around pH 7."},{"Start":"01:14.470 ","End":"01:17.975","Text":"Even a slight change in the overall pH of the body"},{"Start":"01:17.975 ","End":"01:21.605","Text":"actually can result in severe injury or death,"},{"Start":"01:21.605 ","End":"01:24.469","Text":"so this system is very important."},{"Start":"01:24.469 ","End":"01:31.475","Text":"It also allows people to travel and live at high altitudes because at the high altitudes,"},{"Start":"01:31.475 ","End":"01:37.600","Text":"of course, the partial pressure of oxygen and carbon dioxide are lower."},{"Start":"01:37.600 ","End":"01:41.885","Text":"When the partial pressure of carbon dioxide changes at high altitudes,"},{"Start":"01:41.885 ","End":"01:45.350","Text":"the bicarbonate buffer system adjusts to regulate"},{"Start":"01:45.350 ","End":"01:52.140","Text":"the carbon dioxide while maintaining the correct pH in the body."},{"Start":"01:52.310 ","End":"01:59.375","Text":"While carbon dioxide can readily associate and dissociate from hemoglobin as we\u0027ve seen,"},{"Start":"01:59.375 ","End":"02:05.240","Text":"there can be problems called the principal one,"},{"Start":"02:05.240 ","End":"02:08.660","Text":"the worst one is carbon monoxide poisoning."},{"Start":"02:08.660 ","End":"02:13.910","Text":"Because there are other molecules other than carbon dioxide, like carbon monoxide."},{"Start":"02:13.910 ","End":"02:16.460","Text":"That\u0027s, instead of having 2 oxygens,"},{"Start":"02:16.460 ","End":"02:22.885","Text":"we\u0027ve only got 1 that binds carbon monoxide,"},{"Start":"02:22.885 ","End":"02:27.245","Text":"binds hemoglobin very, very avidly."},{"Start":"02:27.245 ","End":"02:28.805","Text":"Where does it come from?"},{"Start":"02:28.805 ","End":"02:31.550","Text":"It\u0027s a colorless, odorless gas,"},{"Start":"02:31.550 ","End":"02:33.450","Text":"making it rather dangerous,"},{"Start":"02:33.450 ","End":"02:37.265","Text":"and it\u0027s produced by gas-powered vehicles"},{"Start":"02:37.265 ","End":"02:42.395","Text":"because the carbon in them is not fully oxidized sometimes,"},{"Start":"02:42.395 ","End":"02:47.555","Text":"and therefore we have carbon monoxide which is emitted."},{"Start":"02:47.555 ","End":"02:50.990","Text":"That can be quite dangerous if we have,"},{"Start":"02:50.990 ","End":"02:54.250","Text":"say, a motor running in a closed space."},{"Start":"02:54.250 ","End":"03:01.205","Text":"As you can see, hemoglobin affinity to carbon monoxide is much,"},{"Start":"03:01.205 ","End":"03:07.110","Text":"much greater, like 240 times that of oxygen."},{"Start":"03:08.150 ","End":"03:16.190","Text":"The carbon monoxide will replace the oxygen that\u0027s bound to the hemoglobin,"},{"Start":"03:16.190 ","End":"03:20.540","Text":"making it such that when carbon monoxide is present,"},{"Start":"03:20.540 ","End":"03:24.470","Text":"then very little of oxygen is transported to the cells,"},{"Start":"03:24.470 ","End":"03:28.255","Text":"the cells are starved for oxygen hypoxia,"},{"Start":"03:28.255 ","End":"03:35.165","Text":"and long-term exposure to carbon monoxide can cause brain damage or even death."},{"Start":"03:35.165 ","End":"03:38.030","Text":"What are the symptoms?"},{"Start":"03:38.030 ","End":"03:42.740","Text":"The symptoms are, depending on how much carbon monoxide,"},{"Start":"03:42.740 ","End":"03:47.120","Text":"there is in the blood it can go all the way from no symptoms"},{"Start":"03:47.120 ","End":"03:52.940","Text":"or say even a slight headache to life-threatening or death?"},{"Start":"03:52.940 ","End":"03:57.530","Text":"Yes, if the percentage of blood goes very intermediary"},{"Start":"03:57.530 ","End":"04:02.045","Text":"symptoms that are important to know are specially getting a headache,"},{"Start":"04:02.045 ","End":"04:06.560","Text":"that your respiratory rate will increase to try to get more oxygen,"},{"Start":"04:06.560 ","End":"04:11.120","Text":"some drowsiness and then start getting confusion,"},{"Start":"04:11.120 ","End":"04:15.830","Text":"shortness of breath, eventually unconsciousness or in seizures,"},{"Start":"04:15.830 ","End":"04:18.878","Text":"it is quite dangerous."},{"Start":"04:18.878 ","End":"04:21.036","Text":"How is it dealt with?"},{"Start":"04:21.036 ","End":"04:23.745","Text":"It\u0027s dealt with by administering"},{"Start":"04:23.745 ","End":"04:31.430","Text":"100 percent oxygen so that there is less carbon monoxide around,"},{"Start":"04:31.430 ","End":"04:40.020","Text":"and hopefully the hemoglobin will take up the oxygen rather than the carbon monoxide."}],"ID":30622},{"Watched":false,"Name":"Oxygen Transport via Hemoglobin in the Blood","Duration":"7m 54s","ChapterTopicVideoID":29027,"CourseChapterTopicPlaylistID":294417,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.810","Text":"Welcome back to our discussion of the transport of"},{"Start":"00:03.810 ","End":"00:09.015","Text":"gases that is really breathing in the human body."},{"Start":"00:09.015 ","End":"00:15.675","Text":"What we know is that oxygen diffuses across the alveoli in the lungs,"},{"Start":"00:15.675 ","End":"00:21.210","Text":"enters the bloodstream and is transported to the tissues where it\u0027s used,"},{"Start":"00:21.210 ","End":"00:24.780","Text":"it\u0027s unloaded into the tissues and conversely,"},{"Start":"00:24.780 ","End":"00:32.420","Text":"carbon dioxide diffuses out"},{"Start":"00:32.420 ","End":"00:36.990","Text":"of the blood and into the alveoli so it can be expelled from the body."},{"Start":"00:36.990 ","End":"00:41.630","Text":"Of course, that carbon dioxide also comes from the tissues."},{"Start":"00:41.630 ","End":"00:47.360","Text":"We have this circular process where oxygen goes"},{"Start":"00:47.360 ","End":"00:49.580","Text":"into the bloodstream and is used in"},{"Start":"00:49.580 ","End":"00:53.360","Text":"the tissues where there\u0027s respiration and carbon dioxide comes back out."},{"Start":"00:53.360 ","End":"00:57.455","Text":"Now, all of this is transported via the blood,"},{"Start":"00:57.455 ","End":"01:03.100","Text":"and in particular the red blood cells, as we\u0027ll see."},{"Start":"01:03.100 ","End":"01:07.250","Text":"The gas exchange is a continuous process."},{"Start":"01:07.250 ","End":"01:12.285","Text":"We discussed the issue of diffusion in a previous video."},{"Start":"01:12.285 ","End":"01:16.205","Text":"The oxygen and carbon dioxide are transported,"},{"Start":"01:16.205 ","End":"01:22.115","Text":"however, through different mechanisms than just dissolving in the blood."},{"Start":"01:22.115 ","End":"01:28.990","Text":"In fact, they are moved via hemoglobin,"},{"Start":"01:28.990 ","End":"01:35.305","Text":"that is, a protein which is found in red blood cells."},{"Start":"01:35.305 ","End":"01:38.780","Text":"Although oxygen does dissolve in the blood,"},{"Start":"01:38.780 ","End":"01:43.355","Text":"only about 1.5 percent of the oxygen is transported that way,"},{"Start":"01:43.355 ","End":"01:51.334","Text":"98.5 percent of the oxygen binds the hemoglobin and then is carried to the body tissues."},{"Start":"01:51.334 ","End":"01:56.215","Text":"Now the hemoglobin is denoted in two different ways,"},{"Start":"01:56.215 ","End":"02:01.000","Text":"either when it\u0027s connected or when oxygen"},{"Start":"02:01.000 ","End":"02:07.660","Text":"is bound to it as HbO_2 or HHb,"},{"Start":"02:07.660 ","End":"02:09.595","Text":"as we see here."},{"Start":"02:09.595 ","End":"02:15.855","Text":"That\u0027s how it\u0027s denoted when the hemoglobin is deoxygenated."},{"Start":"02:15.855 ","End":"02:19.590","Text":"Notice it does not have oxygen in it."},{"Start":"02:19.590 ","End":"02:26.260","Text":"Now the hemoglobin is actually a complicated molecule, very complicated molecule."},{"Start":"02:26.260 ","End":"02:32.710","Text":"It\u0027s a protein that includes within it these disks that are called heme."},{"Start":"02:32.710 ","End":"02:35.755","Text":"This is the chemical nature of the heme."},{"Start":"02:35.755 ","End":"02:42.395","Text":"The heme has an iron atom inside it."},{"Start":"02:42.395 ","End":"02:44.555","Text":"What\u0027s interesting is that,"},{"Start":"02:44.555 ","End":"02:50.119","Text":"1 molecule of hemoglobin is a tetramer."},{"Start":"02:50.119 ","End":"02:53.995","Text":"That means it includes 4 different subunits,"},{"Start":"02:53.995 ","End":"03:00.260","Text":"2 subunits that are called Alpha subunits and 2 subunits called Beta subunits."},{"Start":"03:00.260 ","End":"03:02.720","Text":"They\u0027re a bit different from one another,"},{"Start":"03:02.720 ","End":"03:05.360","Text":"the Alpha and Beta subunits,"},{"Start":"03:05.360 ","End":"03:09.910","Text":"but each of them does contain this heme."},{"Start":"03:10.160 ","End":"03:18.170","Text":"The subunits interact with one another and with these heme groups that hold the iron."},{"Start":"03:18.170 ","End":"03:22.550","Text":"It\u0027s the heme group that is going to bind the oxygen."},{"Start":"03:22.550 ","End":"03:27.455","Text":"Each heme group binds 1 oxygen molecule."},{"Start":"03:27.455 ","End":"03:32.810","Text":"Therefore, each hemoglobin molecule that contains the 4 subunits"},{"Start":"03:32.810 ","End":"03:38.865","Text":"is going to be able to bind 4 oxygen molecules."},{"Start":"03:38.865 ","End":"03:43.565","Text":"Now you know that blood is red and in fact,"},{"Start":"03:43.565 ","End":"03:49.415","Text":"the blood that we usually see when it\u0027s exposed to the air binds oxygen very avidly."},{"Start":"03:49.415 ","End":"03:54.605","Text":"Therefore, we know that it is very bright red but"},{"Start":"03:54.605 ","End":"03:57.590","Text":"the blood which is inside"},{"Start":"03:57.590 ","End":"04:02.090","Text":"the veins that is coming back from the tissue actually is not as bright,"},{"Start":"04:02.090 ","End":"04:09.320","Text":"the venous blood that\u0027s deoxygenated is a darker red color."},{"Start":"04:09.320 ","End":"04:16.610","Text":"Now there is a cooperative effect of binding oxygen to the hemoglobin."},{"Start":"04:16.610 ","End":"04:20.450","Text":"If this is the hemoglobin molecule that has"},{"Start":"04:20.450 ","End":"04:28.220","Text":"the 4 heme groups in it and each one heme in each of the 4 subunits,"},{"Start":"04:28.220 ","End":"04:35.130","Text":"then what we know is that as oxygen binds once, twice,"},{"Start":"04:35.130 ","End":"04:37.820","Text":"3 times, or 4 times,"},{"Start":"04:37.820 ","End":"04:43.865","Text":"the binding constant of each of these bindings is not the same."},{"Start":"04:43.865 ","End":"04:47.087","Text":"As hemoglobin binds successive oxygens,"},{"Start":"04:47.087 ","End":"04:52.895","Text":"the oxygen affinity of each of the subunits increases."},{"Start":"04:52.895 ","End":"04:57.620","Text":"In fact, the affinity of the fourth oxygen that\u0027s bound,"},{"Start":"04:57.620 ","End":"04:59.615","Text":"this one actually in this figure,"},{"Start":"04:59.615 ","End":"05:05.515","Text":"is approximately 300 times that of the first one."},{"Start":"05:05.515 ","End":"05:11.645","Text":"This occurs because the hemoglobin molecule changes its conformation as the oxygen binds,"},{"Start":"05:11.645 ","End":"05:15.170","Text":"making further oxygen binding stronger."},{"Start":"05:15.170 ","End":"05:18.350","Text":"This can be denoted in a curve."},{"Start":"05:18.350 ","End":"05:21.290","Text":"As the oxygen partial pressure increases,"},{"Start":"05:21.290 ","End":"05:24.095","Text":"as there\u0027s more and more oxygen,"},{"Start":"05:24.095 ","End":"05:27.830","Text":"if we look at the amount of hemoglobin or at"},{"Start":"05:27.830 ","End":"05:31.190","Text":"the percentage of hemoglobin which is bound,"},{"Start":"05:31.190 ","End":"05:34.580","Text":"what we do see is that it\u0027s not a linear curve,"},{"Start":"05:34.580 ","End":"05:39.860","Text":"it\u0027s what\u0027s called a sigmoidal curve."},{"Start":"05:39.860 ","End":"05:42.470","Text":"As the partial pressure of oxygen increases,"},{"Start":"05:42.470 ","End":"05:46.070","Text":"the hemoglobin becomes increasingly saturated,"},{"Start":"05:46.070 ","End":"05:49.295","Text":"but not linearly as we said."},{"Start":"05:49.295 ","End":"05:53.885","Text":"Now, the position of this curve can actually move somewhat in"},{"Start":"05:53.885 ","End":"05:59.715","Text":"two different directions as we can see in this figure."},{"Start":"05:59.715 ","End":"06:04.880","Text":"The affinity of the hemoglobin may shift to the left and"},{"Start":"06:04.880 ","End":"06:11.345","Text":"that\u0027s higher or to the right depending on the conditions surrounding the hemoglobin."},{"Start":"06:11.345 ","End":"06:14.216","Text":"Here they call it environmental conditions,"},{"Start":"06:14.216 ","End":"06:15.740","Text":"that is going to be, for instance,"},{"Start":"06:15.740 ","End":"06:17.405","Text":"the pH and the temperature."},{"Start":"06:17.405 ","End":"06:23.810","Text":"If the carbon dioxide in the blood reacts with water to form bicarbonate,"},{"Start":"06:23.810 ","End":"06:25.940","Text":"when it dissolves in the blood,"},{"Start":"06:25.940 ","End":"06:34.190","Text":"it actually turns to bicarbonate and hydrogen atoms that\u0027s going to drive the pH lower."},{"Start":"06:34.190 ","End":"06:38.780","Text":"As the carbon dioxide in the blood increases,"},{"Start":"06:38.780 ","End":"06:44.270","Text":"the pH is produced and the pH decreases, becomes more acidic."},{"Start":"06:44.270 ","End":"06:48.170","Text":"Then what we see is that there is a decrease in"},{"Start":"06:48.170 ","End":"06:54.110","Text":"the pH and there is a reduction in the affinity of hemoglobin for oxygen."},{"Start":"06:54.110 ","End":"06:58.685","Text":"The hemoglobin then will release oxygen more"},{"Start":"06:58.685 ","End":"07:03.515","Text":"easily when there is more carbon dioxide in the blood."},{"Start":"07:03.515 ","End":"07:05.300","Text":"Of course, that\u0027s what we want."},{"Start":"07:05.300 ","End":"07:07.445","Text":"When we have more respiration,"},{"Start":"07:07.445 ","End":"07:09.560","Text":"we\u0027re going to have more carbon dioxide,"},{"Start":"07:09.560 ","End":"07:12.090","Text":"we\u0027re going to need more oxygen."},{"Start":"07:12.090 ","End":"07:18.195","Text":"The hemoglobin has evolved such that that works better"},{"Start":"07:18.195 ","End":"07:25.890","Text":"when the pH goes down and that\u0027s the result of the carbon dioxide going up."},{"Start":"07:26.300 ","End":"07:31.010","Text":"There\u0027s a shift in the opposite direction"},{"Start":"07:31.010 ","End":"07:36.130","Text":"that also results from an increase in body temperature."},{"Start":"07:36.130 ","End":"07:40.909","Text":"Increased temperatures, such as from increased activity of skeletal muscles,"},{"Start":"07:40.909 ","End":"07:44.824","Text":"causes the affinity of hemoglobin for oxygen to be reduced,"},{"Start":"07:44.824 ","End":"07:53.700","Text":"allowing the hemoglobin then to deliver more oxygen to the tissues."}],"ID":30623},{"Watched":false,"Name":"Anemia and the Bicarbonate Buffer System","Duration":"8m 8s","ChapterTopicVideoID":29028,"CourseChapterTopicPlaylistID":294417,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.450","Text":"Welcome back to our discussion of transport of"},{"Start":"00:03.450 ","End":"00:07.650","Text":"oxygen in the blood and our discussion of hemoglobin."},{"Start":"00:07.650 ","End":"00:10.095","Text":"Now, as we all know,"},{"Start":"00:10.095 ","End":"00:12.300","Text":"and as we discussed in the previous video,"},{"Start":"00:12.300 ","End":"00:17.880","Text":"the hemoglobin, which is inside the red blood cells, is a protein."},{"Start":"00:17.880 ","End":"00:20.235","Text":"Proteins, of course,"},{"Start":"00:20.235 ","End":"00:27.840","Text":"can undergo changes via mutations that are in the genes that encode those proteins."},{"Start":"00:27.840 ","End":"00:31.920","Text":"There can be diseases, genetic diseases,"},{"Start":"00:31.920 ","End":"00:37.530","Text":"in which the hemoglobin doesn\u0027t work quite right because of mutations."},{"Start":"00:37.530 ","End":"00:41.570","Text":"These can be inherited if they\u0027re not deadly."},{"Start":"00:41.570 ","End":"00:45.740","Text":"We know of 2 different kinds of anemias."},{"Start":"00:45.740 ","End":"00:47.870","Text":"One of them is well-known,"},{"Start":"00:47.870 ","End":"00:53.095","Text":"is called sickle-cell anemia and the other is thalassemia."},{"Start":"00:53.095 ","End":"00:58.040","Text":"Both of these diseases decrease the blood\u0027s ability to deliver"},{"Start":"00:58.040 ","End":"01:02.795","Text":"oxygen to the tissues and its oxygen carrying capacity."},{"Start":"01:02.795 ","End":"01:05.599","Text":"Now, let\u0027s see how this happens."},{"Start":"01:05.599 ","End":"01:09.950","Text":"Well, in sickle-cell anemia,"},{"Start":"01:09.950 ","End":"01:13.970","Text":"the hemoglobin that\u0027s inside"},{"Start":"01:13.970 ","End":"01:17.480","Text":"these cells forms strands that changes"},{"Start":"01:17.480 ","End":"01:21.456","Text":"the shape of the hemoglobin and makes them sticky to each other,"},{"Start":"01:21.456 ","End":"01:25.130","Text":"so that these strands that are formed inside the cells that"},{"Start":"01:25.130 ","End":"01:29.860","Text":"changes the way the cells are shaped."},{"Start":"01:29.860 ","End":"01:33.135","Text":"Sometimes it will block blood flow."},{"Start":"01:33.135 ","End":"01:40.324","Text":"Not only are these cells not in the ideal shape to exchange oxygen,"},{"Start":"01:40.324 ","End":"01:41.750","Text":"but in addition to that,"},{"Start":"01:41.750 ","End":"01:44.930","Text":"they can get stuck inside blood vessels and this"},{"Start":"01:44.930 ","End":"01:48.785","Text":"causes tremendous amount of pain to these patients."},{"Start":"01:48.785 ","End":"01:55.160","Text":"It also can mean that they will deliver less oxygen to their tissues."},{"Start":"01:55.160 ","End":"01:59.155","Text":"This is a pretty bad disease."},{"Start":"01:59.155 ","End":"02:03.266","Text":"The shape of the red blood cells becomes crescent shaped,"},{"Start":"02:03.266 ","End":"02:05.815","Text":"therefore, the name sickle-cell anemia,"},{"Start":"02:05.815 ","End":"02:07.780","Text":"they become elongated, stiffened,"},{"Start":"02:07.780 ","End":"02:14.965","Text":"and the ability to deliver oxygen through the capillaries is decreased."},{"Start":"02:14.965 ","End":"02:20.715","Text":"In thalassemia, we have a different kind of defect,"},{"Start":"02:20.715 ","End":"02:24.510","Text":"either in the Alpha or Beta subunits of hemoglobin."},{"Start":"02:24.510 ","End":"02:29.605","Text":"In this case, the patients produce a high number of red blood cells,"},{"Start":"02:29.605 ","End":"02:34.540","Text":"but they have less hemoglobin in them than they should."},{"Start":"02:34.540 ","End":"02:39.815","Text":"That results in destruction of these red blood cells anemia."},{"Start":"02:39.815 ","End":"02:44.135","Text":"These patients don\u0027t carry as much oxygen either"},{"Start":"02:44.135 ","End":"02:49.050","Text":"and that can be very detrimental to them as well."},{"Start":"02:49.050 ","End":"02:52.010","Text":"What about carbon dioxide?"},{"Start":"02:52.010 ","End":"02:57.920","Text":"The transport of carbon dioxide in the blood works somewhat differently."},{"Start":"02:57.920 ","End":"03:02.870","Text":"It can bind in a small amount to hemoglobin, as we\u0027ll see."},{"Start":"03:02.870 ","End":"03:09.020","Text":"But most of the carbon dioxide actually is dissolved in the blood in an interesting way."},{"Start":"03:09.020 ","End":"03:14.525","Text":"Carbon dioxide molecules are transported in the blood actually by 3 different methods."},{"Start":"03:14.525 ","End":"03:18.385","Text":"Either the dissolution into the blood between 5 and 7 percent,"},{"Start":"03:18.385 ","End":"03:21.800","Text":"it\u0027s more soluble in the blood than oxygen as you\u0027ve seen."},{"Start":"03:21.800 ","End":"03:24.590","Text":"It can also bind to hemoglobin,"},{"Start":"03:24.590 ","End":"03:28.260","Text":"as we said, that\u0027s about 10 percent."},{"Start":"03:28.260 ","End":"03:32.165","Text":"In that case, what\u0027s going to happen is it\u0027s going to form"},{"Start":"03:32.165 ","End":"03:36.875","Text":"something called carbaminohemoglobin that\u0027s reversible."},{"Start":"03:36.875 ","End":"03:40.415","Text":"But it\u0027s also, in most cases,"},{"Start":"03:40.415 ","End":"03:44.510","Text":"is carried as bicarbonate ion in the blood and"},{"Start":"03:44.510 ","End":"03:50.265","Text":"participates in a bicarbonate buffer system which as you\u0027ll see,"},{"Start":"03:50.265 ","End":"03:52.365","Text":"becomes very important,"},{"Start":"03:52.365 ","End":"03:55.975","Text":"so has 85 percent."},{"Start":"03:55.975 ","End":"03:59.675","Text":"That\u0027s a lot. Let\u0027s concentrate on that."},{"Start":"03:59.675 ","End":"04:02.585","Text":"In the bicarbonate buffer system,"},{"Start":"04:02.585 ","End":"04:08.705","Text":"what we\u0027ll see is that it has a very large role in regulating the pH of the blood."},{"Start":"04:08.705 ","End":"04:10.415","Text":"That\u0027s really important."},{"Start":"04:10.415 ","End":"04:13.625","Text":"If the pH goes badly off,"},{"Start":"04:13.625 ","End":"04:17.660","Text":"it can be deadly for the individual."},{"Start":"04:17.660 ","End":"04:23.030","Text":"Now how does this work? Carbon dioxide diffuses into the red blood cells,"},{"Start":"04:23.030 ","End":"04:25.370","Text":"as you can see here, diffuses from the tissue."},{"Start":"04:25.370 ","End":"04:29.930","Text":"The tissues are making carbon dioxide as a result of respiration."},{"Start":"04:29.930 ","End":"04:35.420","Text":"Then there\u0027s an enzyme inside the cells called carbonic anhydrase,"},{"Start":"04:35.420 ","End":"04:38.420","Text":"CA, inside the red blood cells."},{"Start":"04:38.420 ","End":"04:40.010","Text":"What does that enzyme do?"},{"Start":"04:40.010 ","End":"04:46.850","Text":"It converts the carbon dioxide together with water to carbonic acid."},{"Start":"04:46.850 ","End":"04:51.140","Text":"The carbonic acid very quickly by"},{"Start":"04:51.140 ","End":"04:55.220","Text":"itself and this is a reaction that occurs without any help,"},{"Start":"04:55.220 ","End":"04:58.430","Text":"it dissociates into bicarbonate and"},{"Start":"04:58.430 ","End":"05:07.845","Text":"hydrogen ions because the carbonic acid is unstable."},{"Start":"05:07.845 ","End":"05:15.695","Text":"This then allows for more uptake of carbon dioxide into the red blood cells because"},{"Start":"05:15.695 ","End":"05:19.145","Text":"there is a concentration gradient which is soaking"},{"Start":"05:19.145 ","End":"05:23.005","Text":"up first the carbon dioxide then the carbonic acid."},{"Start":"05:23.005 ","End":"05:31.400","Text":"This reaction then is very fast and it draws more carbon dioxide into the cells."},{"Start":"05:31.400 ","End":"05:36.184","Text":"If too much of the hydrogen is produced,"},{"Start":"05:36.184 ","End":"05:37.880","Text":"then as we said,"},{"Start":"05:37.880 ","End":"05:43.280","Text":"you\u0027ll get a lower pH in the blood cells for"},{"Start":"05:43.280 ","End":"05:49.400","Text":"that matter but hemoglobin has the ability to bind free hydrogen ions."},{"Start":"05:49.400 ","End":"05:56.770","Text":"The pH shift inside these cells is limited by that."},{"Start":"05:56.770 ","End":"06:03.710","Text":"That\u0027s what happens when the blood cells are taking up carbon dioxide."},{"Start":"06:03.710 ","End":"06:05.555","Text":"What about the release?"},{"Start":"06:05.555 ","End":"06:12.313","Text":"When the cells then get to the lungs as we can see in the figure here on the right,"},{"Start":"06:12.313 ","End":"06:16.130","Text":"then we have a shift to the left rather than to the right."},{"Start":"06:16.130 ","End":"06:20.525","Text":"In other words, carbon dioxide needs to leave the red blood cells."},{"Start":"06:20.525 ","End":"06:21.995","Text":"How is that happening?"},{"Start":"06:21.995 ","End":"06:25.190","Text":"Well, it turns out that chloride,"},{"Start":"06:25.190 ","End":"06:27.050","Text":"there\u0027s a chloride ion,"},{"Start":"06:27.050 ","End":"06:30.110","Text":"which is important for this,"},{"Start":"06:30.110 ","End":"06:32.060","Text":"a chloride ion and"},{"Start":"06:32.060 ","End":"06:36.875","Text":"the newly synthesized bicarbonate is transported out of the red blood cell."},{"Start":"06:36.875 ","End":"06:41.725","Text":"The bicarbonate then is going to go."},{"Start":"06:41.725 ","End":"06:48.670","Text":"Now, let\u0027s look at what happens to that bicarbonate molecule."},{"Start":"06:48.670 ","End":"06:53.980","Text":"Well, it actually is transported out of the red blood cells into"},{"Start":"06:53.980 ","End":"07:01.300","Text":"the blood plasma and that occurs in exchange for a chloride ion which goes in."},{"Start":"07:01.300 ","End":"07:04.764","Text":"This is called the chloride shift."},{"Start":"07:04.764 ","End":"07:09.835","Text":"However, when the blood reaches the lungs,"},{"Start":"07:09.835 ","End":"07:11.945","Text":"the opposite has to happen."},{"Start":"07:11.945 ","End":"07:17.335","Text":"That is, the carbon dioxide has to be released from the red blood cells"},{"Start":"07:17.335 ","End":"07:23.075","Text":"and go into the alveoli so that it can be released into the air."},{"Start":"07:23.075 ","End":"07:25.950","Text":"There is a reverse chloride shift."},{"Start":"07:25.950 ","End":"07:29.210","Text":"In this case, the bicarbonate then goes in, again,"},{"Start":"07:29.210 ","End":"07:30.920","Text":"in exchange for chloride,"},{"Start":"07:30.920 ","End":"07:35.670","Text":"which is going now in the opposite direction as it had gone before."},{"Start":"07:35.670 ","End":"07:43.400","Text":"The hydrogen ion dissociates from the hemoglobin and binds the bicarbonate ion,"},{"Start":"07:43.400 ","End":"07:45.120","Text":"which is now inside."},{"Start":"07:45.120 ","End":"07:49.670","Text":"We\u0027ve got to reverse reaction and therefore produces"},{"Start":"07:49.670 ","End":"07:55.100","Text":"this carbonic acid intermediate and that is converted by"},{"Start":"07:55.100 ","End":"07:59.825","Text":"this carbonic anhydrase back in the opposite direction to"},{"Start":"07:59.825 ","End":"08:06.330","Text":"carbon dioxide and the carbon dioxide is expelled from the lungs."}],"ID":30624}],"Thumbnail":null,"ID":294417},{"Name":"Exercises","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Exercise 1","Duration":"1m 6s","ChapterTopicVideoID":29020,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.500","Text":"The respiratory system does which of the following?"},{"Start":"00:04.500 ","End":"00:09.360","Text":"Does it provide body tissues with just oxygen?"},{"Start":"00:09.360 ","End":"00:12.465","Text":"Oxygen, and carbon dioxide?"},{"Start":"00:12.465 ","End":"00:15.870","Text":"Does it establish how many breaths are taken per minute,"},{"Start":"00:15.870 ","End":"00:17.670","Text":"the respiratory system we\u0027re asking?"},{"Start":"00:17.670 ","End":"00:21.930","Text":"Or does it provide the body with carbon dioxide?"},{"Start":"00:21.930 ","End":"00:24.585","Text":"Well, let\u0027s see."},{"Start":"00:24.585 ","End":"00:30.980","Text":"The respiratory system certainly does not provide body tissues with carbon dioxide,"},{"Start":"00:30.980 ","End":"00:32.840","Text":"carbon dioxide is taken away."},{"Start":"00:32.840 ","End":"00:37.040","Text":"It does not establish how many breaths are taken per minute,"},{"Start":"00:37.040 ","End":"00:39.920","Text":"that can be controlled in various ways."},{"Start":"00:39.920 ","End":"00:43.010","Text":"It certainly does not provide the body with CO2,"},{"Start":"00:43.010 ","End":"00:46.355","Text":"so it\u0027s got to be providing the body tissues with oxygen."},{"Start":"00:46.355 ","End":"00:48.550","Text":"Of course, that\u0027s the right answer."},{"Start":"00:48.550 ","End":"00:53.960","Text":"The functions of the respiratory system from the slide that we\u0027ve seen is gas exchange,"},{"Start":"00:53.960 ","End":"01:00.820","Text":"which delivers oxygen to the cells and carbon dioxide waste from the cells,"},{"Start":"01:00.820 ","End":"01:02.975","Text":"so our answer is a,"},{"Start":"01:02.975 ","End":"01:06.720","Text":"provides body tissues with oxygen."}],"ID":30606},{"Watched":false,"Name":"Exercise 2","Duration":"1m 8s","ChapterTopicVideoID":29021,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.790","Text":"Air that we\u0027re breathing is warmed and humidified in the nasal passages."},{"Start":"00:05.790 ","End":"00:07.695","Text":"It\u0027s warmed and humidified."},{"Start":"00:07.695 ","End":"00:09.075","Text":"Well, what\u0027s that for?"},{"Start":"00:09.075 ","End":"00:12.825","Text":"This helps to do which of the following; ward off infection?"},{"Start":"00:12.825 ","End":"00:15.930","Text":"Decreased sensitivity during breathing,"},{"Start":"00:15.930 ","End":"00:18.150","Text":"prevent damage to the lungs,"},{"Start":"00:18.150 ","End":"00:20.820","Text":"or all of the above?"},{"Start":"00:20.820 ","End":"00:25.635","Text":"Ward off infection, decreased sensitivity during breathing."},{"Start":"00:25.635 ","End":"00:27.375","Text":"What is sensitivity mean?"},{"Start":"00:27.375 ","End":"00:29.130","Text":"Prevent damage to the lungs."},{"Start":"00:29.130 ","End":"00:31.275","Text":"Well, let\u0027s see."},{"Start":"00:31.275 ","End":"00:35.065","Text":"It\u0027s not going to be infection."},{"Start":"00:35.065 ","End":"00:38.960","Text":"It\u0027s not going to be decreasing sensitivity."},{"Start":"00:38.960 ","End":"00:40.330","Text":"Certainly not all of the above,"},{"Start":"00:40.330 ","End":"00:42.830","Text":"if those 2 are wrong, prevent damage to the lungs."},{"Start":"00:42.830 ","End":"00:46.519","Text":"So if you remember this slide,"},{"Start":"00:46.519 ","End":"00:50.900","Text":"then what we know is that in mammalian systems,"},{"Start":"00:50.900 ","End":"00:55.550","Text":"the nasal cavity equilibrates the air to body conditions,"},{"Start":"00:55.550 ","End":"00:58.220","Text":"reducing any damage that cold,"},{"Start":"00:58.220 ","End":"00:59.705","Text":"dry air can cause."},{"Start":"00:59.705 ","End":"01:02.045","Text":"So our answer, therefore,"},{"Start":"01:02.045 ","End":"01:07.379","Text":"his gut to be to prevent damage to the lungs."}],"ID":30607},{"Watched":false,"Name":"Exercise 3","Duration":"1m 31s","ChapterTopicVideoID":29010,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.790","Text":"Which is the order of airflow during inhalation?"},{"Start":"00:05.790 ","End":"00:09.495","Text":"Well, let\u0027s look at the various possibilities."},{"Start":"00:09.495 ","End":"00:12.210","Text":"Naval cavity, the trachea,"},{"Start":"00:12.210 ","End":"00:16.215","Text":"the larynx, bronchi, bronchioles or alveoli."},{"Start":"00:16.215 ","End":"00:19.140","Text":"Well alveoli are the end of each of them."},{"Start":"00:19.140 ","End":"00:23.540","Text":"The bronchioles are these 2 and the bronchi are these."},{"Start":"00:23.540 ","End":"00:27.310","Text":"Here\u0027s the difference between these answers."},{"Start":"00:27.310 ","End":"00:28.890","Text":"Which is it going to be,"},{"Start":"00:28.890 ","End":"00:30.690","Text":"the bronchioles or the bronchi?"},{"Start":"00:30.690 ","End":"00:32.370","Text":"Well, bronchioles,"},{"Start":"00:32.370 ","End":"00:33.419","Text":"they\u0027re going to be smaller,"},{"Start":"00:33.419 ","End":"00:35.665","Text":"so it\u0027s got to be either a or b."},{"Start":"00:35.665 ","End":"00:37.835","Text":"Then we have over here,"},{"Start":"00:37.835 ","End":"00:40.360","Text":"we have larynx, trachea,"},{"Start":"00:40.360 ","End":"00:42.740","Text":"or trachea, larynx,"},{"Start":"00:42.740 ","End":"00:46.380","Text":"and they always starts out in the nasal cavity."},{"Start":"00:46.380 ","End":"00:51.570","Text":"Is it going to be trachea and larynx or is it going to be larynx and trachea?"},{"Start":"00:51.570 ","End":"00:58.630","Text":"Well, so remember that the trachea is the tube that leads down the throat deep."},{"Start":"00:58.630 ","End":"01:02.310","Text":"The trachea is going to have to be our answer."},{"Start":"01:02.310 ","End":"01:04.890","Text":"B is going to have to be our answer."},{"Start":"01:04.890 ","End":"01:08.190","Text":"Remember this figure, here is the trachea."},{"Start":"01:08.190 ","End":"01:12.150","Text":"It goes first to the larynx, trachea, bronchi."},{"Start":"01:12.150 ","End":"01:14.805","Text":"Yes, primary and secondary,"},{"Start":"01:14.805 ","End":"01:18.630","Text":"tertiary, the bronchioles, the smaller ones."},{"Start":"01:18.630 ","End":"01:23.575","Text":"Then at the very end of the bronchioles are the alveoli."},{"Start":"01:23.575 ","End":"01:26.704","Text":"Our answers got to be naval cavity,"},{"Start":"01:26.704 ","End":"01:31.080","Text":"larynx, trachea, bronchi, bronchioles, alveoli."}],"ID":30596},{"Watched":false,"Name":"Exercise 4","Duration":"1m 5s","ChapterTopicVideoID":29011,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.645","Text":"The inspiratory reserve volume,"},{"Start":"00:03.645 ","End":"00:06.345","Text":"inspiration that means breathing in."},{"Start":"00:06.345 ","End":"00:09.225","Text":"Reserve volume measures what?"},{"Start":"00:09.225 ","End":"00:13.875","Text":"The amount of air remaining in the lungs after a maximal exhalation?"},{"Start":"00:13.875 ","End":"00:16.725","Text":"The amount of air that the lung holds all together?"},{"Start":"00:16.725 ","End":"00:20.190","Text":"The amount of air that can be further exhaled after a normal breath,"},{"Start":"00:20.190 ","End":"00:26.220","Text":"or the amount of air that can be further inhaled after a normal breath?"},{"Start":"00:26.220 ","End":"00:31.365","Text":"It\u0027s not going to be the amount of air remaining in the lung after"},{"Start":"00:31.365 ","End":"00:36.795","Text":"because that\u0027s the reserve volume after a maximal exhalation."},{"Start":"00:36.795 ","End":"00:38.615","Text":"Not the amount of air the lung holds,"},{"Start":"00:38.615 ","End":"00:40.730","Text":"not the amount of air that can be further exhaled."},{"Start":"00:40.730 ","End":"00:44.420","Text":"The amount of air that can be further inhaled after normal breaths."},{"Start":"00:44.420 ","End":"00:50.570","Text":"Take a normal breath and then we breathe some more that\u0027s the reserve volume."},{"Start":"00:50.570 ","End":"00:53.615","Text":"It\u0027s this reserve volume,"},{"Start":"00:53.615 ","End":"00:59.385","Text":"the IRV, this region here, the extra amount."},{"Start":"00:59.385 ","End":"01:04.440","Text":"It\u0027s the amount of air that can be further inhaled after a normal breath."}],"ID":30597},{"Watched":false,"Name":"Exercise 5","Duration":"1m 36s","ChapterTopicVideoID":29012,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.120","Text":"Of the following, which does not explain why the partial pressure of"},{"Start":"00:06.120 ","End":"00:11.875","Text":"oxygen is lower in the lung than is the external air?"},{"Start":"00:11.875 ","End":"00:15.555","Text":"We\u0027re talking about the partial pressure of oxygen,"},{"Start":"00:15.555 ","End":"00:18.165","Text":"which is lower in the lung."},{"Start":"00:18.165 ","End":"00:20.970","Text":"Air in the lung is humidified, therefore,"},{"Start":"00:20.970 ","End":"00:27.645","Text":"water vapor pressure alters the pressure. That could make sense."},{"Start":"00:27.645 ","End":"00:30.740","Text":"But we\u0027re talking about the partial pressures, is what we\u0027re interested in."},{"Start":"00:30.740 ","End":"00:33.620","Text":"Carbon dioxide mixes with oxygen."},{"Start":"00:33.620 ","End":"00:39.100","Text":"Oxygen is moved into the blood and is headed to the tissues or"},{"Start":"00:39.100 ","End":"00:44.420","Text":"is it that the lungs exert a pressure on the air to reduce the oxygen pressure."},{"Start":"00:44.420 ","End":"00:51.420","Text":"Notice that in this question we\u0027re asked which does not explain."},{"Start":"00:52.880 ","End":"00:57.875","Text":"If you remember, partial pressure in the lungs,"},{"Start":"00:57.875 ","End":"01:05.825","Text":"is influenced by the carbon dioxide coming in,"},{"Start":"01:05.825 ","End":"01:07.790","Text":"the oxygen going out,"},{"Start":"01:07.790 ","End":"01:14.620","Text":"and the partial pressure of water in the lungs so therefore,"},{"Start":"01:14.620 ","End":"01:17.835","Text":"our answer is going to be,"},{"Start":"01:17.835 ","End":"01:21.350","Text":"the ones which does not explain why"},{"Start":"01:21.350 ","End":"01:25.520","Text":"the partial pressure of oxygen is lower in the lung than in the external air will"},{"Start":"01:25.520 ","End":"01:28.580","Text":"be that the lungs exert a pressure on the air because that\u0027s the"},{"Start":"01:28.580 ","End":"01:32.615","Text":"same on all the parts of the air,"},{"Start":"01:32.615 ","End":"01:34.130","Text":"including the carbon dioxide,"},{"Start":"01:34.130 ","End":"01:36.540","Text":"the oxygen, and the water."}],"ID":30598},{"Watched":false,"Name":"Exercise 6","Duration":"50s","ChapterTopicVideoID":29013,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.805","Text":"The total lung capacity."},{"Start":"00:02.805 ","End":"00:08.550","Text":"Total lung capacity is calculated using which of the following formulas?"},{"Start":"00:08.550 ","End":"00:11.640","Text":"So we\u0027ve got a bunch of different things here."},{"Start":"00:11.640 ","End":"00:18.090","Text":"Let\u0027s just go straight to the slide that explains what the total lung capacity is."},{"Start":"00:18.090 ","End":"00:22.020","Text":"The total lung capacity is everything."},{"Start":"00:22.020 ","End":"00:24.360","Text":"The functional residual capacity,"},{"Start":"00:24.360 ","End":"00:27.797","Text":"the normal breath,"},{"Start":"00:27.797 ","End":"00:29.494","Text":"the vital capacity,"},{"Start":"00:29.494 ","End":"00:31.549","Text":"and the inspiratory capacity."},{"Start":"00:31.549 ","End":"00:36.990","Text":"So our answer therefore is going to be the sum of the residual volume,"},{"Start":"00:36.990 ","End":"00:39.740","Text":"expiratory reserve volume, the tidal volume,"},{"Start":"00:39.740 ","End":"00:43.567","Text":"that\u0027s the normal breathing,"},{"Start":"00:43.567 ","End":"00:45.815","Text":"and the inspiratory reserve volume."},{"Start":"00:45.815 ","End":"00:51.030","Text":"So our answer then to the question will be D. All of those things."}],"ID":30599},{"Watched":false,"Name":"Exercise 7","Duration":"1m 56s","ChapterTopicVideoID":29014,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.520","Text":"Here\u0027s an interesting question."},{"Start":"00:02.520 ","End":"00:07.095","Text":"How would paralysis of the diaphragm alter inspiration?"},{"Start":"00:07.095 ","End":"00:10.380","Text":"This is breathing in, inhaling."},{"Start":"00:10.380 ","End":"00:13.980","Text":"Now, the diaphragm is paralyzed."},{"Start":"00:13.980 ","End":"00:16.620","Text":"Could we breathe? What would happen?"},{"Start":"00:16.620 ","End":"00:19.710","Text":"Would it prevent contraction of the intercostal muscles,"},{"Start":"00:19.710 ","End":"00:23.190","Text":"the muscles that move the chest?"},{"Start":"00:23.190 ","End":"00:25.065","Text":"I\u0027m not sure why it would do that."},{"Start":"00:25.065 ","End":"00:30.060","Text":"It would prevent inhalation because the intrapleural pressure would not change,"},{"Start":"00:30.060 ","End":"00:33.840","Text":"so here we have to think about what it is that the diaphragm does,"},{"Start":"00:33.840 ","End":"00:35.775","Text":"and we\u0027ll look at that in a second."},{"Start":"00:35.775 ","End":"00:39.180","Text":"It would decrease the intrapleural pressure and allow"},{"Start":"00:39.180 ","End":"00:44.125","Text":"more air to enter the lungs. Why would it do that?"},{"Start":"00:44.125 ","End":"00:48.710","Text":"It would slow exploration because the lung would not relax,"},{"Start":"00:48.710 ","End":"00:51.035","Text":"we\u0027re talking about inspiration here."},{"Start":"00:51.035 ","End":"00:54.220","Text":"Why would it slow exploration?"},{"Start":"00:54.220 ","End":"00:56.765","Text":"Let\u0027s look at these things."},{"Start":"00:56.765 ","End":"01:00.050","Text":"Certainly has nothing to do with the intercostal muscles."},{"Start":"01:00.050 ","End":"01:03.620","Text":"It will not decrease the intrapleural pressure."},{"Start":"01:03.620 ","End":"01:05.345","Text":"That has nothing to do with it either."},{"Start":"01:05.345 ","End":"01:09.532","Text":"We\u0027d said before that we\u0027re talking about inspiration, not exploration."},{"Start":"01:09.532 ","End":"01:12.740","Text":"So it\u0027s got to be B. Let\u0027s think about this."},{"Start":"01:12.740 ","End":"01:17.356","Text":"The diaphragm, if you remember when it moves down,"},{"Start":"01:17.356 ","End":"01:21.590","Text":"changes the volume of the thoracic activity"},{"Start":"01:21.590 ","End":"01:24.460","Text":"because the diaphragm contracts and moves down"},{"Start":"01:24.460 ","End":"01:27.500","Text":"and the pressure decreases according to Boyle\u0027s law."},{"Start":"01:27.500 ","End":"01:30.875","Text":"Therefore, the lung volume expands and"},{"Start":"01:30.875 ","End":"01:35.960","Text":"the expanding thoracic cavity allows air to rush into the lungs,"},{"Start":"01:35.960 ","End":"01:39.820","Text":"when its volume is increased."},{"Start":"01:40.160 ","End":"01:45.635","Text":"Our answer therefore has to be that if the diaphragm we\u0027re not working,"},{"Start":"01:45.635 ","End":"01:56.620","Text":"it would prevent inhalation because the intrapleural pressure would not change."}],"ID":30600},{"Watched":false,"Name":"Exercise 8","Duration":"1m 41s","ChapterTopicVideoID":29015,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.230","Text":"Here\u0027s a question that regards the function of"},{"Start":"00:04.230 ","End":"00:09.690","Text":"the airways and what happens in restrictive airway diseases."},{"Start":"00:09.690 ","End":"00:14.160","Text":"That is, when the airways become restricted,"},{"Start":"00:14.160 ","End":"00:18.960","Text":"they become such that air can\u0027t pass as well. What happens in these?"},{"Start":"00:18.960 ","End":"00:21.420","Text":"Does it increase the compliance of the lung?"},{"Start":"00:21.420 ","End":"00:23.490","Text":"We have to remember what compliance means,"},{"Start":"00:23.490 ","End":"00:25.560","Text":"decreases the compliance of the lung,"},{"Start":"00:25.560 ","End":"00:28.610","Text":"and after we review that\u0027s what compliance means."},{"Start":"00:28.610 ","End":"00:34.300","Text":"Increases the lung volume or decreases the work of breathing decreases."},{"Start":"00:34.300 ","End":"00:36.485","Text":"The disease will have less work."},{"Start":"00:36.485 ","End":"00:39.275","Text":"Probably not, probably have more work."},{"Start":"00:39.275 ","End":"00:41.990","Text":"It\u0027s not going to increase the compliance."},{"Start":"00:41.990 ","End":"00:44.225","Text":"Let\u0027s look and see what compliance is."},{"Start":"00:44.225 ","End":"00:46.340","Text":"Not going to increase the lung volume"},{"Start":"00:46.340 ","End":"00:49.010","Text":"and it certainly doesn\u0027t decrease the work of breathing."},{"Start":"00:49.010 ","End":"00:51.200","Text":"Lung resistance and compliance."},{"Start":"00:51.200 ","End":"00:54.515","Text":"This was a slide that we saw before."},{"Start":"00:54.515 ","End":"00:58.820","Text":"Pulmonary diseases reduce the rate of gas exchange."},{"Start":"00:58.820 ","End":"01:06.320","Text":"Why? Because of the compliance that is the elasticity of the lung."},{"Start":"01:06.320 ","End":"01:09.875","Text":"If the lung is less elastic,"},{"Start":"01:09.875 ","End":"01:14.845","Text":"there we going to get gas exchange that works less well."},{"Start":"01:14.845 ","End":"01:22.579","Text":"When the restrictive diseases in which the airways are less compliant or stiff,"},{"Start":"01:22.579 ","End":"01:31.620","Text":"we\u0027re not going to be able to breathe as well and that will be restrictive lung disease."},{"Start":"01:31.620 ","End":"01:33.505","Text":"Our answer, therefore,"},{"Start":"01:33.505 ","End":"01:41.070","Text":"is going to be decrease in the compliance or the elasticity of the lung."}],"ID":30601},{"Watched":false,"Name":"Exercise 9","Duration":"1m 26s","ChapterTopicVideoID":29016,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.068","Text":"Alveolar ventilation, that is the air,"},{"Start":"00:04.068 ","End":"00:11.550","Text":"that gets into the alveoli remains constant when which of the following happens?"},{"Start":"00:11.550 ","End":"00:13.665","Text":"Or as you can see, maybe 2 of them."},{"Start":"00:13.665 ","End":"00:19.380","Text":"The respiratory rate is increased while the volume of the air per breath is decreased."},{"Start":"00:19.380 ","End":"00:24.390","Text":"The respiratory rate and the volume of air per breadth are increased."},{"Start":"00:24.390 ","End":"00:29.550","Text":"Here we\u0027ve got respiratory rates and the volume increased."},{"Start":"00:29.550 ","End":"00:32.790","Text":"Well, so that wouldn\u0027t mean that we have anything constant."},{"Start":"00:32.790 ","End":"00:40.565","Text":"How about the respiratory rate is decreased while increasing the volume per breadth."},{"Start":"00:40.565 ","End":"00:46.790","Text":"That could mean maybe both A and C. Let\u0027s see what we remember."},{"Start":"00:46.790 ","End":"00:52.040","Text":"What we remember is that alveolar ventilation, again,"},{"Start":"00:52.040 ","End":"00:56.710","Text":"is how much air moves into and out of the alveoli,"},{"Start":"00:56.710 ","End":"00:59.420","Text":"and that there are 2 ways indeed,"},{"Start":"00:59.420 ","End":"01:02.225","Text":"to keep the alveolar ventilation constant."},{"Start":"01:02.225 ","End":"01:07.040","Text":"One is to increase the respiratory rate while decreasing the tidal volume of air."},{"Start":"01:07.040 ","End":"01:10.945","Text":"That\u0027s the air that\u0027s going in and out during a normal breath."},{"Start":"01:10.945 ","End":"01:14.420","Text":"The other way is to decrease the respiratory rate while"},{"Start":"01:14.420 ","End":"01:19.270","Text":"increasing the amount of air going in per breath, deep breathing."},{"Start":"01:19.270 ","End":"01:23.870","Text":"Our answer therefore is certainly going to be the last one,"},{"Start":"01:23.870 ","End":"01:27.030","Text":"both A and C."}],"ID":30602},{"Watched":false,"Name":"Exercise 10","Duration":"1m 49s","ChapterTopicVideoID":29017,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:08.550","Text":"Which of the following will not facilitate the transfer of oxygen to the tissues?"},{"Start":"00:08.550 ","End":"00:10.575","Text":"Decrease in body temperature,"},{"Start":"00:10.575 ","End":"00:12.465","Text":"decrease in the pH of the blood,"},{"Start":"00:12.465 ","End":"00:17.745","Text":"increased carbon dioxide, or increased exercise."},{"Start":"00:17.745 ","End":"00:20.490","Text":"We\u0027re looking for something which will not facilitate"},{"Start":"00:20.490 ","End":"00:23.055","Text":"the transfer of oxygen to the tissues,"},{"Start":"00:23.055 ","End":"00:27.110","Text":"or what effect does body temperature have on that?"},{"Start":"00:27.110 ","End":"00:30.920","Text":"Certainly the decrease in body temperature."},{"Start":"00:30.920 ","End":"00:33.110","Text":"I don\u0027t think we learned anything about that."},{"Start":"00:33.110 ","End":"00:34.955","Text":"What about decrease in pH?"},{"Start":"00:34.955 ","End":"00:37.115","Text":"We did learn something about that."},{"Start":"00:37.115 ","End":"00:38.909","Text":"Increased carbon dioxide, we did,"},{"Start":"00:38.909 ","End":"00:45.145","Text":"and increased exercise is going to raise the temperature somewhat as well."},{"Start":"00:45.145 ","End":"00:50.435","Text":"It turns out, is going to facilitate transfer of oxygen to the tissues."},{"Start":"00:50.435 ","End":"00:57.200","Text":"Let\u0027s recall this slide in which we were able to"},{"Start":"00:57.200 ","End":"01:04.745","Text":"move this curve either to the left or to the right,"},{"Start":"01:04.745 ","End":"01:08.720","Text":"depending on several different factors."},{"Start":"01:08.720 ","End":"01:13.835","Text":"One of them is CO_2 in the blood reacts with water to form bicarbonate, so CO_2."},{"Start":"01:13.835 ","End":"01:15.619","Text":"Yes, level CO_2 increases."},{"Start":"01:15.619 ","End":"01:19.000","Text":"So that was one thing that changes the pH."},{"Start":"01:19.000 ","End":"01:20.150","Text":"So we\u0027ve got 2 things here,"},{"Start":"01:20.150 ","End":"01:21.845","Text":"carbon dioxide and pH,"},{"Start":"01:21.845 ","End":"01:25.445","Text":"and the last thing was going to be increase of temperature,"},{"Start":"01:25.445 ","End":"01:29.510","Text":"such as from increased activity of skeletal muscle that"},{"Start":"01:29.510 ","End":"01:33.743","Text":"also can decrease the affinity for oxygen."},{"Start":"01:33.743 ","End":"01:36.935","Text":"So which is going to be our answer?"},{"Start":"01:36.935 ","End":"01:43.455","Text":"Which of these is going to not affect the transfer of oxygen?"},{"Start":"01:43.455 ","End":"01:45.960","Text":"The decrease in body temperature,"},{"Start":"01:45.960 ","End":"01:48.670","Text":"so our answer is A."}],"ID":30603},{"Watched":false,"Name":"Exercise 11","Duration":"1m 1s","ChapterTopicVideoID":29018,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.670","Text":"The majority of carbon dioxide in the blood is transported by which of the following?"},{"Start":"00:05.670 ","End":"00:07.515","Text":"Talking about carbon dioxide."},{"Start":"00:07.515 ","End":"00:11.280","Text":"Is it hemoglobin just regular dissolution in the blood?"},{"Start":"00:11.280 ","End":"00:13.680","Text":"Conversion to bicarbonates."},{"Start":"00:13.680 ","End":"00:18.285","Text":"Well, remember the bicarbonate buffering or binding to plasma proteins,"},{"Start":"00:18.285 ","End":"00:20.235","Text":"that we actually didn\u0027t talk about at all."},{"Start":"00:20.235 ","End":"00:23.220","Text":"We\u0027ve talked about hemoglobin, not plasma proteins."},{"Start":"00:23.220 ","End":"00:25.500","Text":"What\u0027s our answer going to be?"},{"Start":"00:25.500 ","End":"00:28.140","Text":"Is binding to hemoglobin,"},{"Start":"00:28.140 ","End":"00:31.830","Text":"the solution in the blood or plasma proteins are not the answers."},{"Start":"00:31.830 ","End":"00:33.830","Text":"If you remember this slide,"},{"Start":"00:33.830 ","End":"00:38.200","Text":"then what you should remember is that the majority,"},{"Start":"00:38.200 ","End":"00:42.575","Text":"85 percent of carbon dioxide is carried as"},{"Start":"00:42.575 ","End":"00:50.585","Text":"a bicarbonate ion inside red blood cells in the bicarbonate buffer system,"},{"Start":"00:50.585 ","End":"00:55.325","Text":"and so our answer is C, conversion to bicarbonate."},{"Start":"00:55.325 ","End":"01:01.950","Text":"The majority of the CO_2 is transported by this conversion to bicarbonate."}],"ID":30604},{"Watched":false,"Name":"Exercise 12","Duration":"38s","ChapterTopicVideoID":29019,"CourseChapterTopicPlaylistID":294418,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.680","Text":"Most of the oxygen in the blood is transported by which?"},{"Start":"00:04.680 ","End":"00:09.240","Text":"The solution in the blood being carried as bicarbonate ions,"},{"Start":"00:09.240 ","End":"00:14.700","Text":"binding to blood plasma or binding to hemoglobin-. That\u0027s easy."},{"Start":"00:14.700 ","End":"00:19.019","Text":"Remember we discussed a lot about hemoglobin binding oxygen."},{"Start":"00:19.019 ","End":"00:20.550","Text":"That\u0027s going to be our answer."},{"Start":"00:20.550 ","End":"00:25.800","Text":"Remember, oxygen binds hemoglobin in the red blood cells,"},{"Start":"00:25.800 ","End":"00:30.810","Text":"and about 98.5 percent of the oxygen binds hemoglobin."},{"Start":"00:30.810 ","End":"00:34.230","Text":"So that\u0027s certainly going to be our answer."},{"Start":"00:34.230 ","End":"00:38.320","Text":"Binding to hemoglobin, d."}],"ID":30605}],"Thumbnail":null,"ID":294418}]

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