[{"Name":"Overview of the Circulatory System","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Open and Closed Circulatory Systems","Duration":"8m 47s","ChapterTopicVideoID":29052,"CourseChapterTopicPlaylistID":294419,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.385","Text":"Hi, students. I\u0027m glad you\u0027re back now to discuss the circulatory system."},{"Start":"00:06.385 ","End":"00:08.320","Text":"In the previous section,"},{"Start":"00:08.320 ","End":"00:12.010","Text":"we talked a lot about breathing and we talked about the exchange of"},{"Start":"00:12.010 ","End":"00:15.738","Text":"gases in and out of the blood,"},{"Start":"00:15.738 ","End":"00:18.130","Text":"but of course, that blood has to move."},{"Start":"00:18.130 ","End":"00:22.150","Text":"It has to get from the lungs where"},{"Start":"00:22.150 ","End":"00:28.525","Text":"it\u0027s oxygenated to the rest of the body,"},{"Start":"00:28.525 ","End":"00:33.265","Text":"to the cells that are in the periphery where the gas exchange can be made."},{"Start":"00:33.265 ","End":"00:35.080","Text":"In addition to that, of course,"},{"Start":"00:35.080 ","End":"00:37.480","Text":"there are nutrients which have to be brought to"},{"Start":"00:37.480 ","End":"00:42.305","Text":"those cells and there are waste products that have to be carried away."},{"Start":"00:42.305 ","End":"00:46.880","Text":"All of that movement is done, of course,"},{"Start":"00:46.880 ","End":"00:49.250","Text":"via the circulatory system,"},{"Start":"00:49.250 ","End":"00:53.300","Text":"and we have the heart at the center which pumps things around."},{"Start":"00:53.300 ","End":"00:59.870","Text":"In this section, what we\u0027re going to be doing is looking at different types"},{"Start":"00:59.870 ","End":"01:07.490","Text":"of hearts and see how various animals move nutrients around."},{"Start":"01:07.490 ","End":"01:10.894","Text":"Of course, in some of the smaller animals,"},{"Start":"01:10.894 ","End":"01:17.030","Text":"we\u0027re going to have simple diffusion which will be sufficient to move things."},{"Start":"01:17.030 ","End":"01:19.480","Text":"Let\u0027s dive into it."},{"Start":"01:19.480 ","End":"01:23.570","Text":"Most animals require a mechanism for transporting"},{"Start":"01:23.570 ","End":"01:28.599","Text":"nutrients throughout their bodies and of course, removing waste products."},{"Start":"01:28.599 ","End":"01:33.320","Text":"Therefore, the circulatory system has evolved over time and we"},{"Start":"01:33.320 ","End":"01:37.310","Text":"we\u0027ll see this from simple diffusion to a complex network of blood vessels."},{"Start":"01:37.310 ","End":"01:41.435","Text":"We can compare this in various organisms."},{"Start":"01:41.435 ","End":"01:46.880","Text":"Of course, at the core of the circulatory system is the heart that pumps"},{"Start":"01:46.880 ","End":"01:53.340","Text":"blood throughout the body from the heart to the extremities."},{"Start":"01:53.650 ","End":"01:56.180","Text":"How does that heart work?"},{"Start":"01:56.180 ","End":"01:58.640","Text":"Well, we\u0027ll look at that a little bit later."},{"Start":"01:58.640 ","End":"02:04.320","Text":"There are intrinsic electrical impulses inside the heart that make it beat."},{"Start":"02:04.320 ","End":"02:05.660","Text":"You\u0027ve heard of pacemakers,"},{"Start":"02:05.660 ","End":"02:07.340","Text":"for instance, which are inserted."},{"Start":"02:07.340 ","End":"02:16.085","Text":"Well, there\u0027s a normal regular native natural pacemaker"},{"Start":"02:16.085 ","End":"02:20.270","Text":"which regulates those pulses under normal situations."},{"Start":"02:20.270 ","End":"02:22.520","Text":"In addition to that, of course, hormones,"},{"Start":"02:22.520 ","End":"02:27.170","Text":"the endocrine system can affect how fast the heart is beating."},{"Start":"02:27.170 ","End":"02:30.185","Text":"Now, we\u0027ll get back to that later."},{"Start":"02:30.185 ","End":"02:33.830","Text":"Right now, we\u0027re just in the introductory section."},{"Start":"02:33.830 ","End":"02:35.840","Text":"Now, in almost all animals,"},{"Start":"02:35.840 ","End":"02:39.980","Text":"the circulatory system is used to transport nutrients and gases throughout"},{"Start":"02:39.980 ","End":"02:45.755","Text":"the body and in small or thin organisms like you can see here,"},{"Start":"02:45.755 ","End":"02:49.084","Text":"very simple diffusion might be sufficient,"},{"Start":"02:49.084 ","End":"02:52.735","Text":"especially if these animals are living in water."},{"Start":"02:52.735 ","End":"02:55.550","Text":"That should be sufficient for nutrient,"},{"Start":"02:55.550 ","End":"02:57.875","Text":"waste, and gas exchange."},{"Start":"02:57.875 ","End":"03:00.140","Text":"However, in larger organisms like let\u0027s"},{"Start":"03:00.140 ","End":"03:02.720","Text":"say this elephant over here and here we can see the ear,"},{"Start":"03:02.720 ","End":"03:06.440","Text":"there are going to be vessels that are going to be"},{"Start":"03:06.440 ","End":"03:11.045","Text":"moving the blood to and from the extremities."},{"Start":"03:11.045 ","End":"03:15.780","Text":"It\u0027s going to be something we might call bulk flow of blood."},{"Start":"03:15.820 ","End":"03:18.560","Text":"Now, in the simplest system,"},{"Start":"03:18.560 ","End":"03:24.992","Text":"we\u0027re going to have a heart which is going to be transporting blood to"},{"Start":"03:24.992 ","End":"03:33.185","Text":"the extremities of the organism where the gas exchange has to occur between the cells."},{"Start":"03:33.185 ","End":"03:39.200","Text":"Not only gas, but all the exchanges have to occur between the cells and the blood,"},{"Start":"03:39.200 ","End":"03:43.610","Text":"and then the blood will be transported back towards the heart."},{"Start":"03:43.610 ","End":"03:48.830","Text":"This kind of a system would be called a closed circulatory"},{"Start":"03:48.830 ","End":"03:54.680","Text":"system because all of the blood is contained inside blood vessels throughout the body."},{"Start":"03:54.680 ","End":"03:57.395","Text":"Of course, the blood flow is unidirectional,"},{"Start":"03:57.395 ","End":"03:59.760","Text":"it goes in only 1 direction,"},{"Start":"03:59.760 ","End":"04:06.515","Text":"and it\u0027s a systemic circulatory route because it returns back to the heart."},{"Start":"04:06.515 ","End":"04:13.863","Text":"Of course, there is high pressure on 1 end and lower pressure on the other end and"},{"Start":"04:13.863 ","End":"04:17.215","Text":"this high pressure that\u0027s moving things quickly"},{"Start":"04:17.215 ","End":"04:21.430","Text":"allows organisms to have a higher metabolism."},{"Start":"04:21.430 ","End":"04:25.284","Text":"We can find this kind of a closed system,"},{"Start":"04:25.284 ","End":"04:28.127","Text":"notice without any lungs or gills,"},{"Start":"04:28.127 ","End":"04:31.360","Text":"in earthworms, vertebrates, that of course are going"},{"Start":"04:31.360 ","End":"04:35.335","Text":"to have lungs and gills, and some mollusks."},{"Start":"04:35.335 ","End":"04:38.905","Text":"We\u0027ll see different examples of this and see how"},{"Start":"04:38.905 ","End":"04:43.390","Text":"different organisms handle these closed systems."},{"Start":"04:43.390 ","End":"04:45.085","Text":"In addition to that, however,"},{"Start":"04:45.085 ","End":"04:48.830","Text":"there are also open systems."},{"Start":"04:48.830 ","End":"04:50.390","Text":"What\u0027s an open system?"},{"Start":"04:50.390 ","End":"04:55.700","Text":"In open system, we\u0027re going to have a heart indeed that\u0027s going to be pumping blood."},{"Start":"04:55.700 ","End":"04:59.330","Text":"However, it\u0027s not going to be connected"},{"Start":"04:59.330 ","End":"05:06.035","Text":"necessarily at the extremities or at the various cellular systems."},{"Start":"05:06.035 ","End":"05:10.775","Text":"It can spill out into the area between the cells."},{"Start":"05:10.775 ","End":"05:14.755","Text":"That will be called the hemocoel."},{"Start":"05:14.755 ","End":"05:21.620","Text":"That\u0027s the cavity that is between the cells and the blood we\u0027ll call it, actually,"},{"Start":"05:21.620 ","End":"05:25.250","Text":"hemolymph because it mixes with the interstitial fluid,"},{"Start":"05:25.250 ","End":"05:32.085","Text":"that\u0027s the fluid which is between the systems and it\u0027s not enclosed as we said."},{"Start":"05:32.085 ","End":"05:34.610","Text":"The hemolymph does circulate however,"},{"Start":"05:34.610 ","End":"05:38.540","Text":"we do have a heart and it circulates around the body."},{"Start":"05:38.540 ","End":"05:41.180","Text":"Notice it\u0027s not unidirectional."},{"Start":"05:41.180 ","End":"05:44.060","Text":"It\u0027s going in both directions here and"},{"Start":"05:44.060 ","End":"05:49.430","Text":"therefore there\u0027ll be gas exchange and exchange of nutrients and so on,"},{"Start":"05:49.430 ","End":"05:52.535","Text":"and waste products at the organs."},{"Start":"05:52.535 ","End":"05:55.130","Text":"They will eventually reach the heart again,"},{"Start":"05:55.130 ","End":"05:59.165","Text":"and enter the heart through something called ostea."},{"Start":"05:59.165 ","End":"06:01.400","Text":"These little holes that are there."},{"Start":"06:01.400 ","End":"06:06.005","Text":"These kinds of systems are found in arthropods like this grasshopper over here,"},{"Start":"06:06.005 ","End":"06:10.480","Text":"insects, crustaceans, and most mollusks."},{"Start":"06:10.480 ","End":"06:14.060","Text":"Let\u0027s compare the 2 different systems,"},{"Start":"06:14.060 ","End":"06:17.030","Text":"the closed and open systems."},{"Start":"06:17.030 ","End":"06:20.360","Text":"On the left, we\u0027ll have open circulatory system,"},{"Start":"06:20.360 ","End":"06:23.920","Text":"on the right, the closed circulatory system."},{"Start":"06:23.920 ","End":"06:26.340","Text":"In the open circulatory system,"},{"Start":"06:26.340 ","End":"06:31.415","Text":"the blood flows through large open spaces,"},{"Start":"06:31.415 ","End":"06:33.710","Text":"this interstitial area and channels that are called"},{"Start":"06:33.710 ","End":"06:37.205","Text":"lacunae and sinuses among the tissues."},{"Start":"06:37.205 ","End":"06:39.440","Text":"In closed circulatory systems, the blood,"},{"Start":"06:39.440 ","End":"06:42.665","Text":"of course, stays inside the blood vessels."},{"Start":"06:42.665 ","End":"06:47.870","Text":"In open systems, the tissues are in direct contact with the blood,"},{"Start":"06:47.870 ","End":"06:52.655","Text":"but in closed systems the blood does not come in direct contact with the tissue."},{"Start":"06:52.655 ","End":"06:56.300","Text":"Instead, we\u0027re going to see that the blood is in contact"},{"Start":"06:56.300 ","End":"07:01.405","Text":"only with the capillaries and there\u0027s going to be diffusion through capillaries."},{"Start":"07:01.405 ","End":"07:04.280","Text":"In open system, the blood flow is of"},{"Start":"07:04.280 ","End":"07:07.145","Text":"course going to be very slow and the pressure will be low."},{"Start":"07:07.145 ","End":"07:08.660","Text":"In the closed system,"},{"Start":"07:08.660 ","End":"07:11.660","Text":"the blood flow is rapid and the pressure is high."},{"Start":"07:11.660 ","End":"07:14.870","Text":"In open systems, the exchange of gases and nutrients"},{"Start":"07:14.870 ","End":"07:18.670","Text":"takes place between the blood and the tissues."},{"Start":"07:18.670 ","End":"07:21.905","Text":"We\u0027re going to have exchange of gases be"},{"Start":"07:21.905 ","End":"07:26.450","Text":"directly between the blood and the tissues when we don\u0027t have the capillaries."},{"Start":"07:26.450 ","End":"07:28.070","Text":"However, in the closed system,"},{"Start":"07:28.070 ","End":"07:33.340","Text":"we\u0027ve got this capillary walls through which the nutrients and gases must pass."},{"Start":"07:33.340 ","End":"07:36.710","Text":"The open system is going to be less efficient because"},{"Start":"07:36.710 ","End":"07:40.445","Text":"the blood is flowing more slowly and furthermore,"},{"Start":"07:40.445 ","End":"07:45.470","Text":"it can\u0027t be controlled as well as it can in a closed system."},{"Start":"07:45.470 ","End":"07:47.885","Text":"The amount of blood that\u0027s getting to"},{"Start":"07:47.885 ","End":"07:51.920","Text":"certain tissues may be slower or faster depending on"},{"Start":"07:51.920 ","End":"07:59.430","Text":"the anatomy and does not have anything to do with blood vessels."},{"Start":"07:59.570 ","End":"08:04.835","Text":"Enclosed system, it\u0027s going to be a more efficient delivery system"},{"Start":"08:04.835 ","End":"08:07.250","Text":"because the blood can be regulated by"},{"Start":"08:07.250 ","End":"08:10.655","Text":"the contraction and relaxation of the blood vessels."},{"Start":"08:10.655 ","End":"08:14.530","Text":"We know that the arteries actually have"},{"Start":"08:14.530 ","End":"08:19.925","Text":"muscles in them which can contract and that can make the pressure higher."},{"Start":"08:19.925 ","End":"08:23.495","Text":"Finally, in open systems,"},{"Start":"08:23.495 ","End":"08:29.810","Text":"there may or may not be a respiratory pigment like hemoglobin kind of thing,"},{"Start":"08:29.810 ","End":"08:30.965","Text":"but if there is,"},{"Start":"08:30.965 ","End":"08:32.869","Text":"it\u0027s dissolved in the plasma,"},{"Start":"08:32.869 ","End":"08:34.925","Text":"not in red blood cells."},{"Start":"08:34.925 ","End":"08:37.910","Text":"In closed circulatory systems, usually,"},{"Start":"08:37.910 ","End":"08:45.960","Text":"there are red blood cells and the respiratory pigment is usually present."}],"ID":30636},{"Watched":false,"Name":"Open Circulatory Systems","Duration":"4m 33s","ChapterTopicVideoID":29053,"CourseChapterTopicPlaylistID":294419,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.945","Text":"We\u0027re going to continue our discussion of the circulatory system in invertebrates."},{"Start":"00:06.945 ","End":"00:10.962","Text":"What we\u0027d saw before with the open and closed systems,"},{"Start":"00:10.962 ","End":"00:15.180","Text":"were systems that were in larger organisms,"},{"Start":"00:15.180 ","End":"00:19.740","Text":"then we\u0027re going to be talking about narrow or at least more complicated ones."},{"Start":"00:19.740 ","End":"00:26.790","Text":"In these systems, we\u0027re not going to need a circulatory system with blood at all."},{"Start":"00:26.790 ","End":"00:30.210","Text":"In the simplest animals and they can still be pretty large,"},{"Start":"00:30.210 ","End":"00:32.288","Text":"like sponges for instance,"},{"Start":"00:32.288 ","End":"00:37.080","Text":"they use diffusion directly from the water that\u0027s around"},{"Start":"00:37.080 ","End":"00:42.345","Text":"them to exchange gases, nutrients, and waste."},{"Start":"00:42.345 ","End":"00:44.090","Text":"How does that work?"},{"Start":"00:44.090 ","End":"00:50.435","Text":"The way it works is on the outside of the sponges the water flows in,"},{"Start":"00:50.435 ","End":"00:53.710","Text":"there are the muscles which pump it in."},{"Start":"00:53.710 ","End":"00:57.170","Text":"Then it goes through the center of the sponge,"},{"Start":"00:57.170 ","End":"00:59.585","Text":"see the water exits over here."},{"Start":"00:59.585 ","End":"01:03.590","Text":"Along the way there\u0027s diffusion of the water,"},{"Start":"01:03.590 ","End":"01:06.020","Text":"gasses, nutrients, and waste."},{"Start":"01:06.020 ","End":"01:09.170","Text":"That\u0027s 1 way to take care of things."},{"Start":"01:09.170 ","End":"01:12.890","Text":"Another way, say in jellies,"},{"Start":"01:12.890 ","End":"01:15.350","Text":"like in jellyfish, for instance,"},{"Start":"01:15.350 ","End":"01:17.750","Text":"comb jellies, these are a bit more complex,"},{"Start":"01:17.750 ","End":"01:19.475","Text":"believe it or not, than these sponges,"},{"Start":"01:19.475 ","End":"01:24.305","Text":"and they also use diffusion through their epidermis, through the skin,"},{"Start":"01:24.305 ","End":"01:31.070","Text":"the outside walls, and inside they have a gastrovascular compartment."},{"Start":"01:31.070 ","End":"01:38.209","Text":"It\u0027s a compartment that does move water through to increase the rate of diffusion."},{"Start":"01:38.209 ","End":"01:42.800","Text":"However, these systems are still relatively simple compared"},{"Start":"01:42.800 ","End":"01:47.705","Text":"to more complex circulatory systems of the kind we looked at a little bit earlier."},{"Start":"01:47.705 ","End":"01:50.600","Text":"in more complex organisms,"},{"Start":"01:50.600 ","End":"01:57.080","Text":"the diffusion is not so efficient and therefore they\u0027re going to require this heart."},{"Start":"01:57.080 ","End":"01:59.915","Text":"For instance, in this grasshopper,"},{"Start":"01:59.915 ","End":"02:05.345","Text":"which is going to transport blood, yes,"},{"Start":"02:05.345 ","End":"02:07.300","Text":"but not through a closed system,"},{"Start":"02:07.300 ","End":"02:11.165","Text":"and of course his blood is called hemolymph, into the sinuses."},{"Start":"02:11.165 ","End":"02:13.340","Text":"There is a circulatory system."},{"Start":"02:13.340 ","End":"02:17.110","Text":"It\u0027s going to be an open one,"},{"Start":"02:17.110 ","End":"02:22.385","Text":"which is what most arthropods and many mollusks have this open circulatory system."},{"Start":"02:22.385 ","End":"02:26.794","Text":"In this case, we have the heart pushing in 1 direction,"},{"Start":"02:26.794 ","End":"02:29.945","Text":"pushing this hemolymph through the body."},{"Start":"02:29.945 ","End":"02:34.325","Text":"The movement around the body is aided by"},{"Start":"02:34.325 ","End":"02:40.020","Text":"muscle contraction that helps move things through the body."},{"Start":"02:40.490 ","End":"02:44.180","Text":"In other organisms,"},{"Start":"02:44.180 ","End":"02:47.990","Text":"besides the arthropods but still invertebrates, let\u0027s say,"},{"Start":"02:47.990 ","End":"02:51.230","Text":"crustaceans including lobsters,"},{"Start":"02:51.230 ","End":"02:55.005","Text":"they have some an intermediary system."},{"Start":"02:55.005 ","End":"03:00.020","Text":"They do have these arteries that push things out,"},{"Start":"03:00.020 ","End":"03:03.575","Text":"but still the system is an open system."},{"Start":"03:03.575 ","End":"03:08.600","Text":"Blood is moved into various parts of the body where it then returns"},{"Start":"03:08.600 ","End":"03:15.785","Text":"between the cells back into the interstitial space,"},{"Start":"03:15.785 ","End":"03:20.300","Text":"but it\u0027s deliberate to the extremities more efficiently through"},{"Start":"03:20.300 ","End":"03:28.115","Text":"these little arteries and that supplies precise blood supply to specific organs."},{"Start":"03:28.115 ","End":"03:30.515","Text":"Let\u0027s look at another example."},{"Start":"03:30.515 ","End":"03:33.410","Text":"Here\u0027s an invertebrates like active mollusks,"},{"Start":"03:33.410 ","End":"03:35.345","Text":"I say, squids for instance."},{"Start":"03:35.345 ","End":"03:40.220","Text":"Those organisms did evolve closed circulatory systems."},{"Start":"03:40.220 ","End":"03:44.075","Text":"That\u0027s because they need to be able to move very rapidly."},{"Start":"03:44.075 ","End":"03:46.370","Text":"The squid, for instance,"},{"Start":"03:46.370 ","End":"03:48.725","Text":"can swim very quickly."},{"Start":"03:48.725 ","End":"03:52.775","Text":"They also have gills in which they"},{"Start":"03:52.775 ","End":"03:58.345","Text":"can collect or do gas exchange with the water around them."},{"Start":"03:58.345 ","End":"04:04.275","Text":"They\u0027re going to have a systemic heart and they\u0027re going to have these gills."},{"Start":"04:04.275 ","End":"04:09.680","Text":"You\u0027ll see there\u0027s a systemic area and there is a bronchial heart."},{"Start":"04:09.680 ","End":"04:17.930","Text":"There are actually these 2 hearts that are pushing the blood around."},{"Start":"04:17.930 ","End":"04:25.700","Text":"Still, this is a closed circulatory system that is more characteristic of vertebrates."},{"Start":"04:25.700 ","End":"04:32.430","Text":"Let\u0027s turn our attention in the next videos to vertebrates."}],"ID":30637},{"Watched":false,"Name":"Closed Circulatory Systems","Duration":"7m 58s","ChapterTopicVideoID":29051,"CourseChapterTopicPlaylistID":294419,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.025","Text":"In our previous discussions of the circulatory system in the previous video,"},{"Start":"00:05.025 ","End":"00:07.665","Text":"we were talking about"},{"Start":"00:07.665 ","End":"00:12.240","Text":"open circulatory systems in organisms"},{"Start":"00:12.240 ","End":"00:16.530","Text":"that are not vertebrates or invertebrates of various sorts."},{"Start":"00:16.530 ","End":"00:20.250","Text":"Now what we\u0027re doing is we\u0027re going to be turning our attention"},{"Start":"00:20.250 ","End":"00:24.300","Text":"to closed circulatory systems that are"},{"Start":"00:24.300 ","End":"00:32.745","Text":"going to be delivering blood in a much more controlled way than happens in open systems."},{"Start":"00:32.745 ","End":"00:37.890","Text":"Now, vertebrate systems have a lot less variety than all the variety that we saw in"},{"Start":"00:37.890 ","End":"00:43.370","Text":"the previous video than those of invertebrates because the blood is pumped by a heart,"},{"Start":"00:43.370 ","End":"00:49.655","Text":"and does not normally fill the body cavity in these closed systems."},{"Start":"00:49.655 ","End":"00:51.275","Text":"In addition to that,"},{"Start":"00:51.275 ","End":"00:53.060","Text":"there are specialized molecules,"},{"Start":"00:53.060 ","End":"00:55.040","Text":"the hemoglobin molecules in the blood,"},{"Start":"00:55.040 ","End":"00:57.225","Text":"which transport the oxygen."},{"Start":"00:57.225 ","End":"00:58.860","Text":"In many vertebrates,"},{"Start":"00:58.860 ","End":"01:04.595","Text":"actually in addition to this circulatory system that we call the cardiovascular system,"},{"Start":"01:04.595 ","End":"01:08.660","Text":"there\u0027s another system that\u0027s called the lymphatic system,"},{"Start":"01:08.660 ","End":"01:13.940","Text":"which does not go through the heart that moves things around as well,"},{"Start":"01:13.940 ","End":"01:17.210","Text":"primarily cells that have to do with the immune system."},{"Start":"01:17.210 ","End":"01:20.525","Text":"But we\u0027re not going to be looking at that here."},{"Start":"01:20.525 ","End":"01:23.010","Text":"We\u0027re talking about vertebrates."},{"Start":"01:23.010 ","End":"01:25.520","Text":"Let\u0027s start looking at fish."},{"Start":"01:25.520 ","End":"01:30.109","Text":"At fish, they have the simplest circulatory system, the vertebrates,"},{"Start":"01:30.109 ","End":"01:35.490","Text":"and they have 1 circuit where the blood flows through the heart."},{"Start":"01:35.490 ","End":"01:38.900","Text":"Here\u0027s the heart. Then it goes to"},{"Start":"01:38.900 ","End":"01:44.020","Text":"the area which does the gas exchange to the outside through the gills."},{"Start":"01:44.020 ","End":"01:45.960","Text":"Of course, there are capillaries."},{"Start":"01:45.960 ","End":"01:48.418","Text":"Now the blood is oxygenated,"},{"Start":"01:48.418 ","End":"01:52.610","Text":"and it moves back around into what\u0027s called the systemic circulation,"},{"Start":"01:52.610 ","End":"01:56.570","Text":"that\u0027s going to be the capillaries that are near the organs,"},{"Start":"01:56.570 ","End":"02:00.795","Text":"and then go through the veins back to the heart."},{"Start":"02:00.795 ","End":"02:05.840","Text":"These organisms, these fish, have 1 circuit."},{"Start":"02:05.840 ","End":"02:10.280","Text":"We\u0027ll see later that in many cases there are more than 1 circuit where"},{"Start":"02:10.280 ","End":"02:14.765","Text":"the blood flows in 1 direction from a 2-chambered heart."},{"Start":"02:14.765 ","End":"02:18.665","Text":"Notice we have an atrium and we have a ventricle,"},{"Start":"02:18.665 ","End":"02:23.030","Text":"and we\u0027ll have that in more complicated hearts as well,"},{"Start":"02:23.030 ","End":"02:25.144","Text":"pushing in 1 direction."},{"Start":"02:25.144 ","End":"02:27.630","Text":"This is only a 2-chambered heart."},{"Start":"02:27.630 ","End":"02:31.040","Text":"We have gill circulation through the capillaries,"},{"Start":"02:31.040 ","End":"02:37.905","Text":"and we have systemic circulation through the body of the fish."},{"Start":"02:37.905 ","End":"02:43.018","Text":"This case we do have unidirectional flow of blood,"},{"Start":"02:43.018 ","End":"02:48.620","Text":"and there is a gradient of oxygenated blood,"},{"Start":"02:48.620 ","End":"02:50.090","Text":"of course, through the system."},{"Start":"02:50.090 ","End":"02:53.015","Text":"What\u0027s in the heart is going to be least oxygenated,"},{"Start":"02:53.015 ","End":"02:58.315","Text":"and what\u0027s coming out of the gills is going to be the most oxygenated."},{"Start":"02:58.315 ","End":"03:03.710","Text":"The result of this system is that there is a limit in the amount of oxygen that can"},{"Start":"03:03.710 ","End":"03:09.460","Text":"reach some tissues of the body because it\u0027s only a single system."},{"Start":"03:09.460 ","End":"03:14.660","Text":"This reduces the overall metabolic capacity of the fish"},{"Start":"03:14.660 ","End":"03:21.775","Text":"compared to more complicated plans like we can see here."},{"Start":"03:21.775 ","End":"03:25.250","Text":"In other vertebrates, in amphibians, reptiles,"},{"Start":"03:25.250 ","End":"03:27.575","Text":"and birds, and of course in mammals,"},{"Start":"03:27.575 ","End":"03:29.269","Text":"there are 2 circuits."},{"Start":"03:29.269 ","End":"03:34.030","Text":"There\u0027s what\u0027s called the pulmonary circulation."},{"Start":"03:34.030 ","End":"03:39.455","Text":"In some amphibians, there\u0027s a gas exchange in addition to that through the skin."},{"Start":"03:39.455 ","End":"03:44.360","Text":"There\u0027s pulmonary circulation and there is systemic circulation."},{"Start":"03:44.360 ","End":"03:46.413","Text":"They are separated,"},{"Start":"03:46.413 ","End":"03:48.078","Text":"these 2 systems,"},{"Start":"03:48.078 ","End":"03:52.415","Text":"unlike the fish where it\u0027s all 1 system."},{"Start":"03:52.415 ","End":"03:57.875","Text":"Getting back to a diagram which is similar to what we saw in the fish,"},{"Start":"03:57.875 ","End":"04:02.345","Text":"here we have the heart circulating blood"},{"Start":"04:02.345 ","End":"04:07.490","Text":"from the heart to the lungs and then back to the heart and we have"},{"Start":"04:07.490 ","End":"04:11.465","Text":"the heart circulating blood from the heart through"},{"Start":"04:11.465 ","End":"04:17.570","Text":"the systemic capillaries and then back to the heart into separate systems."},{"Start":"04:17.570 ","End":"04:20.195","Text":"In amphibians, notice,"},{"Start":"04:20.195 ","End":"04:23.825","Text":"we don\u0027t have a 2-chambered heart like we did in fish,"},{"Start":"04:23.825 ","End":"04:27.035","Text":"rather we have a 3-chambered heart."},{"Start":"04:27.035 ","End":"04:30.488","Text":"We have 2 atria up here,"},{"Start":"04:30.488 ","End":"04:35.030","Text":"and we have 1 large ventricle. What does that mean?"},{"Start":"04:35.030 ","End":"04:40.564","Text":"That means that the blood which is returning from the lungs is"},{"Start":"04:40.564 ","End":"04:46.655","Text":"also mixing with blood which is returning from the system."},{"Start":"04:46.655 ","End":"04:49.075","Text":"It\u0027s mixing over here."},{"Start":"04:49.075 ","End":"04:51.405","Text":"We\u0027ll see that in a second."},{"Start":"04:51.405 ","End":"04:57.395","Text":"The atria receive blood from both the pulmonary and the systemic circulations."},{"Start":"04:57.395 ","End":"05:04.768","Text":"Therefore, there\u0027s mixing of the oxygenated and deoxygenated blood in this 1 ventricle,"},{"Start":"05:04.768 ","End":"05:08.510","Text":"and that is going to reduce the efficiency of oxygenation,"},{"Start":"05:08.510 ","End":"05:11.915","Text":"of course, because it\u0027s mixing with the oxygenated."},{"Start":"05:11.915 ","End":"05:15.890","Text":"However, in order to help out with this,"},{"Start":"05:15.890 ","End":"05:20.145","Text":"there is a ridge within the ventricle."},{"Start":"05:20.145 ","End":"05:23.255","Text":"There\u0027s a ridge which is over here,"},{"Start":"05:23.255 ","End":"05:31.270","Text":"which helps direct the blood in the right direction so that it can get better oxygenated."},{"Start":"05:31.270 ","End":"05:40.160","Text":"There is this ridge that diverts oxygen-rich blood to the systemic capillaries,"},{"Start":"05:40.160 ","End":"05:46.120","Text":"and the deoxygenated blood into the pulmonary circuit."},{"Start":"05:46.120 ","End":"05:48.845","Text":"The advantage of this system, of course,"},{"Start":"05:48.845 ","End":"05:56.075","Text":"is that there\u0027s high pressure in the vessels that pushes blood both into the lungs,"},{"Start":"05:56.075 ","End":"05:59.060","Text":"and into the systemic capillaries."},{"Start":"05:59.060 ","End":"06:02.600","Text":"That\u0027s the advantage over fish that only have"},{"Start":"06:02.600 ","End":"06:08.170","Text":"this 2-chamber system and don\u0027t have the 2 different separate systems."},{"Start":"06:08.170 ","End":"06:11.180","Text":"Because of this, these 2 systems,"},{"Start":"06:11.180 ","End":"06:15.650","Text":"amphibians are often described as having double circulation."},{"Start":"06:15.650 ","End":"06:19.190","Text":"Now in reptiles, they have a similar situation."},{"Start":"06:19.190 ","End":"06:24.090","Text":"Also there are 2 atria and 1 ventricle."},{"Start":"06:24.260 ","End":"06:27.200","Text":"Here\u0027s the 3-chambered heart."},{"Start":"06:27.200 ","End":"06:32.105","Text":"However, there is again this partial septum,"},{"Start":"06:32.105 ","End":"06:36.770","Text":"and there\u0027s an additional artery that you can see"},{"Start":"06:36.770 ","End":"06:42.395","Text":"here which comes out and joins the systemic capillary."},{"Start":"06:42.395 ","End":"06:46.115","Text":"In principle, it\u0027s really the same as in amphibians."},{"Start":"06:46.115 ","End":"06:47.420","Text":"Reptiles and amphibians, of course,"},{"Start":"06:47.420 ","End":"06:48.920","Text":"are very closely related."},{"Start":"06:48.920 ","End":"06:54.215","Text":"But there is a little bit of a change such"},{"Start":"06:54.215 ","End":"06:59.990","Text":"that they can deal with particular systems more efficiently."},{"Start":"06:59.990 ","End":"07:09.855","Text":"For instance, alligators and crocodiles have something called a foramen of Panizza."},{"Start":"07:09.855 ","End":"07:11.900","Text":"They have these 2 aortas."},{"Start":"07:11.900 ","End":"07:14.600","Text":"They have the right one arising from the left ventricle and"},{"Start":"07:14.600 ","End":"07:17.120","Text":"the left one coming from the right ventricle,"},{"Start":"07:17.120 ","End":"07:19.017","Text":"as you can see here,"},{"Start":"07:19.017 ","End":"07:23.790","Text":"and they\u0027re connected by this foramen of Panizza as we said."},{"Start":"07:23.790 ","End":"07:27.320","Text":"That allows blood from the right ventricle to bypass"},{"Start":"07:27.320 ","End":"07:30.880","Text":"the pulmonary circulation when the animal is submerged."},{"Start":"07:30.880 ","End":"07:33.604","Text":"When the animal is submerged and can\u0027t breathe,"},{"Start":"07:33.604 ","End":"07:35.390","Text":"the alligators and crocodiles,"},{"Start":"07:35.390 ","End":"07:43.720","Text":"then the pulmonary section is shut down by a particular kind of valve."},{"Start":"07:43.720 ","End":"07:49.505","Text":"Therefore it continues moving blood around into its extremities,"},{"Start":"07:49.505 ","End":"07:52.175","Text":"but not through the lungs,"},{"Start":"07:52.175 ","End":"07:57.570","Text":"which are non-functional because the animal is submerged."}],"ID":30638},{"Watched":false,"Name":"Circulatory System in Mammals and Birds","Duration":"2m 8s","ChapterTopicVideoID":29054,"CourseChapterTopicPlaylistID":294419,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.505","Text":"I\u0027m glad you\u0027re back now to continue our discussion of the circulatory system."},{"Start":"00:05.505 ","End":"00:09.870","Text":"We\u0027ve been talking about open and closed circulatory systems,"},{"Start":"00:09.870 ","End":"00:16.935","Text":"and now we\u0027re going to be turning our attention finally really to mammals and birds."},{"Start":"00:16.935 ","End":"00:23.240","Text":"That\u0027s what\u0027s going to really concern us more since we of course are mammals."},{"Start":"00:23.240 ","End":"00:26.610","Text":"We had seen hearts that only had 3 chambers,"},{"Start":"00:26.610 ","End":"00:30.389","Text":"remember 2 atria and 1 ventricle."},{"Start":"00:30.389 ","End":"00:36.945","Text":"Now we\u0027re looking at a heart in which there is a division into 4 chambers."},{"Start":"00:36.945 ","End":"00:41.700","Text":"There are 2 atria and 2 ventricles,"},{"Start":"00:41.700 ","End":"00:48.500","Text":"and the oxygenated blood therefore is totally separated from the deoxygenated blood."},{"Start":"00:48.500 ","End":"00:50.495","Text":"Remember in the previous system,"},{"Start":"00:50.495 ","End":"00:57.045","Text":"the oxygenated and the deoxygenated blood mixed in the single ventricle,"},{"Start":"00:57.045 ","End":"01:02.990","Text":"here the ventricle is split so there is no mixing of the blood."},{"Start":"01:02.990 ","End":"01:10.280","Text":"It\u0027s split by this septum is what it\u0027s called the area between the 2 ventricles,"},{"Start":"01:10.280 ","End":"01:15.665","Text":"and of course there are some birth defects in which there\u0027s a hole in the septum"},{"Start":"01:15.665 ","End":"01:18.410","Text":"that needs to be repaired otherwise the baby will not be able"},{"Start":"01:18.410 ","End":"01:21.850","Text":"to oxygenate it\u0027s blood as well as it should."},{"Start":"01:21.850 ","End":"01:27.240","Text":"Interestingly, the 4 chambered hearts that we have both in birds and in"},{"Start":"01:27.240 ","End":"01:33.220","Text":"mammals evolved independently from a 3 chambered heart,"},{"Start":"01:33.220 ","End":"01:37.520","Text":"so there\u0027s this independent evolution and that\u0027s called"},{"Start":"01:37.520 ","End":"01:42.680","Text":"convergent evolution when we arrive at the same solution but is"},{"Start":"01:42.680 ","End":"01:45.258","Text":"separately at 2 separate times and"},{"Start":"01:45.258 ","End":"01:49.250","Text":"that evidentially is what happened"},{"Start":"01:49.250 ","End":"01:53.945","Text":"with the evolution of birds and mammals that evolved separately."},{"Start":"01:53.945 ","End":"01:58.555","Text":"Birds, of course, tend to have a larger heart than mammals because"},{"Start":"01:58.555 ","End":"02:06.390","Text":"birds need higher metabolic demands so that they can fly."}],"ID":30639}],"Thumbnail":null,"ID":294419},{"Name":"Components of the Blood","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Components of the Blood","Duration":"5m 33s","ChapterTopicVideoID":29066,"CourseChapterTopicPlaylistID":294420,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.620","Text":"Glad you\u0027re back. Now we\u0027re going to be discussing what\u0027s in the blood,"},{"Start":"00:06.620 ","End":"00:08.505","Text":"the components of the blood."},{"Start":"00:08.505 ","End":"00:09.780","Text":"In the previous videos,"},{"Start":"00:09.780 ","End":"00:12.750","Text":"we talked about how the blood does"},{"Start":"00:12.750 ","End":"00:16.530","Text":"gas exchange and we talked about how it\u0027s moved around the body,"},{"Start":"00:16.530 ","End":"00:20.460","Text":"but we didn\u0027t really look at the cells that are in the blood and"},{"Start":"00:20.460 ","End":"00:25.680","Text":"that\u0027s what the coming videos are going to concentrate on."},{"Start":"00:25.680 ","End":"00:30.450","Text":"As you know, hemoglobin is responsible for distributing the oxygen,"},{"Start":"00:30.450 ","End":"00:31.890","Text":"a little bit of carbon dioxide also,"},{"Start":"00:31.890 ","End":"00:37.040","Text":"but mostly it binds oxygen,"},{"Start":"00:37.040 ","End":"00:42.949","Text":"and it\u0027s then moved throughout the circulatory system in many vertebrates,"},{"Start":"00:42.949 ","End":"00:51.300","Text":"many invertebrates, to bring oxygen to the body or to the cells of the body."},{"Start":"00:51.300 ","End":"00:55.670","Text":"Of course, the blood itself contains not only hemoglobin,"},{"Start":"00:55.670 ","End":"00:59.915","Text":"it contains the red blood cells that contain the hemoglobin."},{"Start":"00:59.915 ","End":"01:05.210","Text":"We can divide actually the blood into different parts."},{"Start":"01:05.210 ","End":"01:11.360","Text":"We can talk about plasma and we can talk about the cells that are in it,"},{"Start":"01:11.360 ","End":"01:13.640","Text":"and we can talk about the cell fragments."},{"Start":"01:13.640 ","End":"01:17.990","Text":"The blood, if we were to spin it down in a centrifuge,"},{"Start":"01:17.990 ","End":"01:22.340","Text":"what we would find is we have cells at the bottom which make"},{"Start":"01:22.340 ","End":"01:27.610","Text":"up about 46 percent or so of the cells,"},{"Start":"01:27.610 ","End":"01:31.045","Text":"of the volume of our tube."},{"Start":"01:31.045 ","End":"01:33.020","Text":"Red blood cells is almost all of it,"},{"Start":"01:33.020 ","End":"01:37.628","Text":"and then we will see there are all other kinds of blood cells in addition,"},{"Start":"01:37.628 ","End":"01:41.375","Text":"and then we have a liquid part, a plasma part."},{"Start":"01:41.375 ","End":"01:44.760","Text":"These are the different kinds of blood cells,"},{"Start":"01:44.760 ","End":"01:48.895","Text":"and we\u0027ll get into a lot more detail with that."},{"Start":"01:48.895 ","End":"01:52.450","Text":"The interstitial fluid that surrounds the cells,"},{"Start":"01:52.450 ","End":"01:55.780","Text":"like we talked about interstitial fluid in the tissues."},{"Start":"01:55.780 ","End":"01:58.435","Text":"Here the blood actually is a tissue."},{"Start":"01:58.435 ","End":"02:02.515","Text":"We can talk about the interstitial fluid that\u0027s around them."},{"Start":"02:02.515 ","End":"02:05.745","Text":"That\u0027s really going to be the plasma."},{"Start":"02:05.745 ","End":"02:07.535","Text":"The blood, believe it or not,"},{"Start":"02:07.535 ","End":"02:15.700","Text":"is about 20 percent of a person\u0027s extracellular fluid and 8 percent of the weight."},{"Start":"02:15.700 ","End":"02:19.860","Text":"We know that they\u0027re all different kinds of cells in this blood,"},{"Start":"02:19.860 ","End":"02:23.995","Text":"and what we need to do now is to look at them in greater detail."},{"Start":"02:23.995 ","End":"02:30.230","Text":"Of course, the role of blood in the body is through the red blood cells to"},{"Start":"02:30.230 ","End":"02:36.905","Text":"bring oxygen to the tissues and to bring carbon dioxide back,"},{"Start":"02:36.905 ","End":"02:39.650","Text":"and to bring food and waste products."},{"Start":"02:39.650 ","End":"02:43.070","Text":"But as we\u0027ll see, it\u0027s much more complicated than that."},{"Start":"02:43.070 ","End":"02:46.534","Text":"It\u0027s important for regulation of the body systems in general"},{"Start":"02:46.534 ","End":"02:50.255","Text":"and for maintaining things as they are, homeostasis."},{"Start":"02:50.255 ","End":"02:56.495","Text":"Homeostasis is established by stabilizing the pH of the blood,"},{"Start":"02:56.495 ","End":"02:58.119","Text":"of the temperature of the blood,"},{"Start":"02:58.119 ","End":"03:02.175","Text":"and of the body therefore and of course, the osmotic pressure."},{"Start":"03:02.175 ","End":"03:05.990","Text":"It supports growth by distributing the nutrients and hormones."},{"Start":"03:05.990 ","End":"03:08.420","Text":"We haven\u0027t discussed hormones lately,"},{"Start":"03:08.420 ","End":"03:09.500","Text":"but of course,"},{"Start":"03:09.500 ","End":"03:14.780","Text":"the hormones have to be distributed through the body as well and removing waste."},{"Start":"03:14.780 ","End":"03:18.065","Text":"It also plays a protective role by"},{"Start":"03:18.065 ","End":"03:22.925","Text":"transporting clotting factors so that if we have an injury for instance,"},{"Start":"03:22.925 ","End":"03:26.585","Text":"then this injury needs to be repaired."},{"Start":"03:26.585 ","End":"03:31.400","Text":"There are clotting factors that will stop the bleeding and that includes platelets,"},{"Start":"03:31.400 ","End":"03:33.080","Text":"as we\u0027ll see a bit later."},{"Start":"03:33.080 ","End":"03:34.835","Text":"In addition to that,"},{"Start":"03:34.835 ","End":"03:41.620","Text":"if we are exposed to some external challenges like let\u0027s say viruses or bacteria,"},{"Start":"03:41.620 ","End":"03:48.185","Text":"then we have disease-fighting white blood cells that are also carried inside the blood."},{"Start":"03:48.185 ","End":"03:52.610","Text":"Now, let\u0027s look at red blood cells first."},{"Start":"03:52.610 ","End":"03:55.440","Text":"They\u0027re also called erythrocytes."},{"Start":"03:55.460 ","End":"03:59.645","Text":"These are specialized oxygen-delivering cells, of course,"},{"Start":"03:59.645 ","End":"04:01.175","Text":"and as we\u0027ll see,"},{"Start":"04:01.175 ","End":"04:04.550","Text":"they are formed from stem cells."},{"Start":"04:04.550 ","End":"04:07.700","Text":"These are cells that are going to become"},{"Start":"04:07.700 ","End":"04:11.435","Text":"erythrocytes through a process called erythropoiesis,"},{"Start":"04:11.435 ","End":"04:13.290","Text":"and it\u0027s done in the bone marrow."},{"Start":"04:13.290 ","End":"04:18.417","Text":"Here we can see a femur and the leg and inside there is bone marrow,"},{"Start":"04:18.417 ","End":"04:22.009","Text":"that\u0027s where the erythropoiesis occurs."},{"Start":"04:22.009 ","End":"04:29.120","Text":"In mammals, these cells are small biconcave cells."},{"Start":"04:29.120 ","End":"04:30.850","Text":"That is, they look like charms,"},{"Start":"04:30.850 ","End":"04:32.720","Text":"kind of like Lucky Charms."},{"Start":"04:32.720 ","End":"04:36.440","Text":"They\u0027re concave, they\u0027re not spherical."},{"Start":"04:36.440 ","End":"04:39.360","Text":"They\u0027re about 7-8 microns in diameter,"},{"Start":"04:39.360 ","End":"04:44.315","Text":"and at maturity, they don\u0027t have a nucleus and they don\u0027t have mitochondria."},{"Start":"04:44.315 ","End":"04:46.160","Text":"We\u0027ll see why in a bit."},{"Start":"04:46.160 ","End":"04:48.095","Text":"In birds, on the other hand,"},{"Start":"04:48.095 ","End":"04:50.255","Text":"the nucleus is still there."},{"Start":"04:50.255 ","End":"04:52.610","Text":"The average lifespan of these cells,"},{"Start":"04:52.610 ","End":"04:58.865","Text":"that is how long they stay in the bloodstream is about 120 days."},{"Start":"04:58.865 ","End":"05:05.440","Text":"After that, there is a very complicated cycle which"},{"Start":"05:05.440 ","End":"05:08.714","Text":"occurs in which the cells are broken down"},{"Start":"05:08.714 ","End":"05:13.145","Text":"because the cells have aged and they need to be replenished with new ones."},{"Start":"05:13.145 ","End":"05:19.550","Text":"They\u0027re broken down and parts of them are recycled in the liver and spleen."},{"Start":"05:19.550 ","End":"05:23.000","Text":"Of course, the iron that\u0027s in the hemoglobin is especially"},{"Start":"05:23.000 ","End":"05:27.440","Text":"valuable and it is returned to the bone marrow."},{"Start":"05:27.440 ","End":"05:33.450","Text":"The rest of it gets excreted eventually in various ways."}],"ID":30655},{"Watched":false,"Name":"Red Blood Cells","Duration":"6m 28s","ChapterTopicVideoID":29063,"CourseChapterTopicPlaylistID":294420,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.290 ","End":"00:04.920","Text":"Now getting back to our discussion of the components of the blood,"},{"Start":"00:04.920 ","End":"00:07.485","Text":"let\u0027s zero in on hemoglobin."},{"Start":"00:07.485 ","End":"00:11.190","Text":"This is a little bit of what we\u0027ve in an earlier video."},{"Start":"00:11.190 ","End":"00:15.990","Text":"Of course, the red coloring of the blood comes from the iron which"},{"Start":"00:15.990 ","End":"00:22.350","Text":"is encased in this very complicated molecule called heme."},{"Start":"00:22.350 ","End":"00:30.390","Text":"In this large complex we have heme and at the center of which is 1 iron atom."},{"Start":"00:30.390 ","End":"00:32.850","Text":"In hemoglobin as you\u0027ll remember,"},{"Start":"00:32.850 ","End":"00:39.305","Text":"we\u0027ve got 4 different peptides."},{"Start":"00:39.305 ","End":"00:44.195","Text":"We\u0027ve got 2 Alphas and 2 Beta chains,"},{"Start":"00:44.195 ","End":"00:47.900","Text":"and each of them contains 1 heme in them."},{"Start":"00:47.900 ","End":"00:53.855","Text":"Of course, the main task is to carry oxygen and a little bit of carbon dioxide,"},{"Start":"00:53.855 ","End":"00:57.710","Text":"the oxygen will attach to the iron."},{"Start":"00:57.710 ","End":"01:05.780","Text":"In addition to the 2 Alpha chains and 2 Beta chains we\u0027ve got the iron which by"},{"Start":"01:05.780 ","End":"01:13.670","Text":"carrying oxygen is oxidized from iron 2 to iron 3."},{"Start":"01:13.670 ","End":"01:19.355","Text":"Amazingly, there is tremendous capacity for carrying oxygen in the blood."},{"Start":"01:19.355 ","End":"01:26.095","Text":"Each blood cell contains about 250 million molecules of"},{"Start":"01:26.095 ","End":"01:33.189","Text":"hemoglobin and as we know each molecule of hemoglobin can carry 4 oxygen molecules,"},{"Start":"01:33.189 ","End":"01:37.550","Text":"so that\u0027s a billion oxygen molecules per blood cell."},{"Start":"01:37.550 ","End":"01:43.535","Text":"If we measure this by the number of erythrocytes that we have in the body,"},{"Start":"01:43.535 ","End":"01:49.730","Text":"we end up with a tremendous number of molecules of oxygen,"},{"Start":"01:49.730 ","End":"01:56.770","Text":"about 25 times 10^21 molecules of oxygen in the body at any one time."},{"Start":"01:56.770 ","End":"02:00.250","Text":"There\u0027s enormous amount of oxygen."},{"Start":"02:00.250 ","End":"02:04.331","Text":"Now, these erythrocytes have become very specialized."},{"Start":"02:04.331 ","End":"02:06.410","Text":"As you can see their shape here they have"},{"Start":"02:06.410 ","End":"02:13.325","Text":"a very large surface area and actually they carry very little other than"},{"Start":"02:13.325 ","End":"02:18.192","Text":"this hemoglobin to the extent where in mammals for instance"},{"Start":"02:18.192 ","End":"02:23.345","Text":"they have lost their nuclei because they don\u0027t divide."},{"Start":"02:23.345 ","End":"02:25.280","Text":"They have lost their nuclei,"},{"Start":"02:25.280 ","End":"02:30.740","Text":"they\u0027re anucleated, and this gives more room for the hemoglobin."},{"Start":"02:30.740 ","End":"02:32.135","Text":"In addition to that,"},{"Start":"02:32.135 ","End":"02:33.800","Text":"they don\u0027t have mitochondria."},{"Start":"02:33.800 ","End":"02:35.840","Text":"I mean you remember mitochondria are"},{"Start":"02:35.840 ","End":"02:41.115","Text":"the engines which produce energy and that uses oxygen."},{"Start":"02:41.115 ","End":"02:45.650","Text":"In order not to use that oxygen they have lost their mitochondria,"},{"Start":"02:45.650 ","End":"02:48.350","Text":"and that\u0027s one reason they have to be turned over from time to time."},{"Start":"02:48.350 ","End":"02:53.485","Text":"This increases the efficiency of oxygen transport."},{"Start":"02:53.485 ","End":"02:57.620","Text":"We know that there are some animals like birds for"},{"Start":"02:57.620 ","End":"03:01.160","Text":"instance in which their erythrocytes are nucleated,"},{"Start":"03:01.160 ","End":"03:04.250","Text":"they do have nuclei in them and an advantage of that is"},{"Start":"03:04.250 ","End":"03:07.595","Text":"of course that these cells can undergo mitosis."},{"Start":"03:07.595 ","End":"03:12.620","Text":"They can divide themselves without go and renew"},{"Start":"03:12.620 ","End":"03:18.745","Text":"themselves that way without the erythropoiesis which is necessary in mammals."},{"Start":"03:18.745 ","End":"03:24.310","Text":"Hemoglobin is not the only molecule that can carry oxygen."},{"Start":"03:24.310 ","End":"03:25.765","Text":"In other organisms,"},{"Start":"03:25.765 ","End":"03:30.595","Text":"so you can see these other organisms over here besides vertebrates,"},{"Start":"03:30.595 ","End":"03:39.535","Text":"there are other kinds of pigments which can carry oxygen as well."},{"Start":"03:39.535 ","End":"03:42.940","Text":"Some of them are copper-based,"},{"Start":"03:42.940 ","End":"03:45.560","Text":"some of them are iron-based."},{"Start":"03:45.560 ","End":"03:50.560","Text":"As you can see they have different names here and therefore are"},{"Start":"03:50.560 ","End":"03:56.110","Text":"different colors depending on whether they\u0027re containing copper, or iron,"},{"Start":"03:56.110 ","End":"03:58.563","Text":"or exactly how they\u0027re arranged,"},{"Start":"03:58.563 ","End":"04:08.890","Text":"but in any case they\u0027re carrying capacity of oxygen is not as good as hemoglobin is."},{"Start":"04:08.890 ","End":"04:18.650","Text":"Now the oxygen delivery we know is especially efficient because of"},{"Start":"04:18.650 ","End":"04:21.020","Text":"this large surface area of the cell as I mentioned"},{"Start":"04:21.020 ","End":"04:23.510","Text":"earlier which allows for rapid diffusion"},{"Start":"04:23.510 ","End":"04:28.479","Text":"of gases across the plasma membrane of the red blood cell,"},{"Start":"04:28.479 ","End":"04:31.430","Text":"and in the lungs, carbon dioxide is released,"},{"Start":"04:31.430 ","End":"04:32.990","Text":"oxygen taken up,"},{"Start":"04:32.990 ","End":"04:36.645","Text":"and in the tissues the opposite of course happens."},{"Start":"04:36.645 ","End":"04:43.130","Text":"Now, hemoglobin as it turns out can also bind something called nitrous oxide,"},{"Start":"04:43.130 ","End":"04:46.290","Text":"which is found in fairly large amounts."},{"Start":"04:46.290 ","End":"04:47.555","Text":"What\u0027s it do?"},{"Start":"04:47.555 ","End":"04:49.310","Text":"It\u0027s a vasodilator."},{"Start":"04:49.310 ","End":"04:53.585","Text":"That means that it can make the blood vessels relax,"},{"Start":"04:53.585 ","End":"04:55.130","Text":"open a little bit,"},{"Start":"04:55.130 ","End":"05:01.490","Text":"the capillaries then can allow more blood flow through and that can help gas exchange,"},{"Start":"05:01.490 ","End":"05:07.910","Text":"and also the passage of red blood cells through capillaries which may be very narrow."},{"Start":"05:07.910 ","End":"05:12.140","Text":"Now on the outside of the red blood cells,"},{"Start":"05:12.140 ","End":"05:15.260","Text":"we find glycolipids and glycoproteins."},{"Start":"05:15.260 ","End":"05:17.693","Text":"Glyco remember means carbohydrate,"},{"Start":"05:17.693 ","End":"05:21.675","Text":"so they\u0027re going to have sugars on the outside of the cells."},{"Start":"05:21.675 ","End":"05:26.685","Text":"The sugars are going to be specific on the outside."},{"Start":"05:26.685 ","End":"05:32.915","Text":"There are many different kinds of glycoproteins like this,"},{"Start":"05:32.915 ","End":"05:41.310","Text":"the best known are glycoproteins which give us the different blood types: A, B, and O."},{"Start":"05:41.310 ","End":"05:44.220","Text":"Individuals that have type"},{"Start":"05:44.220 ","End":"05:50.330","Text":"A glycoproteins are going to be called type A individuals, same thing with B."},{"Start":"05:50.330 ","End":"05:53.990","Text":"We know that there are people who are AB that means they\u0027ve got both of them,"},{"Start":"05:53.990 ","End":"06:04.450","Text":"and type O individuals simply don\u0027t have either A glycoproteins or B glycoproteins."},{"Start":"06:04.450 ","End":"06:09.590","Text":"The presence or absence of the surface glycoproteins will classify"},{"Start":"06:09.590 ","End":"06:14.340","Text":"people as being A, B, or O,"},{"Start":"06:14.340 ","End":"06:20.960","Text":"and then in addition to that there is another glycoprotein called Rh which we will"},{"Start":"06:20.960 ","End":"06:29.190","Text":"see can also determine blood type and we\u0027ll come back to this a little bit later."}],"ID":30656},{"Watched":false,"Name":"White Blood Cells","Duration":"5m 7s","ChapterTopicVideoID":29065,"CourseChapterTopicPlaylistID":294420,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.915","Text":"Now we\u0027re going to continue our discussion of different cells that are in the blood."},{"Start":"00:06.915 ","End":"00:09.930","Text":"We\u0027ve talked about red blood cells in the previous video,"},{"Start":"00:09.930 ","End":"00:15.435","Text":"now we\u0027re going to be talking about white blood cells, known as leukocytes."},{"Start":"00:15.435 ","End":"00:19.905","Text":"Red blood cells are really erythrocytes as we mentioned before it\u0027s 1 kind of"},{"Start":"00:19.905 ","End":"00:25.565","Text":"cell but there are many different kinds of white blood cells."},{"Start":"00:25.565 ","End":"00:28.910","Text":"They\u0027re called leukocytes because leuko means"},{"Start":"00:28.910 ","End":"00:33.470","Text":"white and they make up only about 1 percent of the volume of the cells in the blood."},{"Start":"00:33.470 ","End":"00:38.615","Text":"Remember when we spun down the cells in the previous video,"},{"Start":"00:38.615 ","End":"00:43.790","Text":"we saw that there was this little white section above the red blood cells,"},{"Start":"00:43.790 ","End":"00:48.060","Text":"those are the leukocytes or the white blood cells."},{"Start":"00:48.060 ","End":"00:53.330","Text":"These additional cells, these white blood cells are primarily"},{"Start":"00:53.330 ","End":"00:59.960","Text":"involved in the immune response and they identify various target pathogens."},{"Start":"00:59.960 ","End":"01:02.150","Text":"They\u0027re quite complicated,"},{"Start":"01:02.150 ","End":"01:05.450","Text":"as you can see there are different cell types and we\u0027ll be talking about them"},{"Start":"01:05.450 ","End":"01:08.765","Text":"in a minute and they continually form."},{"Start":"01:08.765 ","End":"01:11.645","Text":"Some of them live for hours or days and some of them"},{"Start":"01:11.645 ","End":"01:15.590","Text":"can live for much longer even for years."},{"Start":"01:15.590 ","End":"01:20.660","Text":"Unlike erythrocytes they do have nuclei and they do"},{"Start":"01:20.660 ","End":"01:25.775","Text":"not contain hemoglobin because their job is not to carry oxygen."},{"Start":"01:25.775 ","End":"01:29.080","Text":"The distinct types are identified,"},{"Start":"01:29.080 ","End":"01:32.630","Text":"as you can see there are lots of different types here by their appearance under"},{"Start":"01:32.630 ","End":"01:38.195","Text":"the microscope and they have various functions that we\u0027ll talk about."},{"Start":"01:38.195 ","End":"01:43.540","Text":"As you can see in their production there is,"},{"Start":"01:43.540 ","End":"01:45.850","Text":"remember we talked about erythropoiesis,"},{"Start":"01:45.850 ","End":"01:47.515","Text":"the making of erythrocytes,"},{"Start":"01:47.515 ","End":"01:52.465","Text":"well, there are stem cells that are multi potential."},{"Start":"01:52.465 ","End":"01:56.380","Text":"That is, their hematopoietic stem cells"},{"Start":"01:56.380 ","End":"02:01.140","Text":"that can form progenitors or they are progenitors really"},{"Start":"02:01.140 ","End":"02:05.080","Text":"for different kinds of cells and they go in"},{"Start":"02:05.080 ","End":"02:10.500","Text":"different pathways to make the different kinds of cells."},{"Start":"02:10.500 ","End":"02:14.260","Text":"Let\u0027s start out by talking about granulocytes."},{"Start":"02:14.260 ","End":"02:18.460","Text":"These include cells that are called neutrophils,"},{"Start":"02:18.460 ","End":"02:20.890","Text":"eosinophils, and basophils."},{"Start":"02:20.890 ","End":"02:25.440","Text":"If we look at them they have a load nucleus,"},{"Start":"02:25.440 ","End":"02:33.133","Text":"that is a nucleus is not ovoid like normal nuclei are in both of these cases."},{"Start":"02:33.133 ","End":"02:36.230","Text":"If you look at them under the microscope they also have"},{"Start":"02:36.230 ","End":"02:40.819","Text":"these granular inclusions and therefore they\u0027re called granulocytes,"},{"Start":"02:40.819 ","End":"02:44.645","Text":"the name was given by the people that first saw them."},{"Start":"02:44.645 ","End":"02:50.440","Text":"Their job is to be the first responders during injury or infection."},{"Start":"02:50.440 ","End":"02:56.164","Text":"If there is some infection in the blood or someplace else even,"},{"Start":"02:56.164 ","End":"03:01.670","Text":"these cells will first go to try to control the problem."},{"Start":"03:01.670 ","End":"03:04.460","Text":"In addition to the granulocytes,"},{"Start":"03:04.460 ","End":"03:08.090","Text":"there are also agranulocytes."},{"Start":"03:08.090 ","End":"03:12.390","Text":"Those are primarily called monocytes and we\u0027ll"},{"Start":"03:12.390 ","End":"03:16.440","Text":"see that they are going to undergo phagocytosis,"},{"Start":"03:16.440 ","End":"03:20.070","Text":"they\u0027re going to be eating larger molecules."},{"Start":"03:20.070 ","End":"03:25.025","Text":"The lymphocytes are going to include B cells and"},{"Start":"03:25.025 ","End":"03:30.905","Text":"T cells which are going to be responsible for adaptive immune response."},{"Start":"03:30.905 ","End":"03:36.814","Text":"That means that when the body sees something foreign"},{"Start":"03:36.814 ","End":"03:39.710","Text":"it not only responds by trying to destroy"},{"Start":"03:39.710 ","End":"03:43.295","Text":"what\u0027s there but it also will remember in a certain way,"},{"Start":"03:43.295 ","End":"03:48.490","Text":"its adaptive immune response and there are 2 different cells called B and T cells,"},{"Start":"03:48.490 ","End":"03:52.400","Text":"lymphocytes which are involved with that."},{"Start":"03:52.400 ","End":"03:56.230","Text":"The monocytes differentiate into macrophages."},{"Start":"03:56.230 ","End":"03:58.880","Text":"These monocytes they\u0027re going to differentiate into"},{"Start":"03:58.880 ","End":"04:01.265","Text":"something called macrophages and dendritic cells,"},{"Start":"04:01.265 ","End":"04:04.730","Text":"cells which are going to be responders as well."},{"Start":"04:04.730 ","End":"04:06.860","Text":"So what are macrophages?"},{"Start":"04:06.860 ","End":"04:10.385","Text":"Makro means big because these are very big cells,"},{"Start":"04:10.385 ","End":"04:13.260","Text":"phages, something that eats,"},{"Start":"04:13.260 ","End":"04:15.450","Text":"so these are macrophages."},{"Start":"04:15.450 ","End":"04:18.225","Text":"Phagein these are Greek words."},{"Start":"04:18.225 ","End":"04:21.045","Text":"In a differentiated monocytes,"},{"Start":"04:21.045 ","End":"04:26.165","Text":"so here\u0027s a monocyte which differentiates into a macrophage."},{"Start":"04:26.165 ","End":"04:32.380","Text":"These are very large specialized cells that recognize in golf and destroy target cells."},{"Start":"04:32.380 ","End":"04:37.070","Text":"They\u0027re stationary, they can\u0027t move on their own but they do move through"},{"Start":"04:37.070 ","End":"04:42.725","Text":"the bloodstream and gather at sites of infection or inflammation."},{"Start":"04:42.725 ","End":"04:46.830","Text":"They\u0027re attracted to these various sites of infection,"},{"Start":"04:46.830 ","End":"04:50.420","Text":"inflammation by various chemicals that are excreted"},{"Start":"04:50.420 ","End":"04:54.845","Text":"by other cells or from foreign particles."},{"Start":"04:54.845 ","End":"04:58.205","Text":"They can survive actually quite a long time,"},{"Start":"04:58.205 ","End":"05:02.045","Text":"for even for months at a time and they, as we said,"},{"Start":"05:02.045 ","End":"05:06.900","Text":"it can be the first line of defense from infection."}],"ID":30657},{"Watched":false,"Name":"Lymphocytes and Platelets","Duration":"6m 39s","ChapterTopicVideoID":29062,"CourseChapterTopicPlaylistID":294420,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.980","Text":"I\u0027m glad you\u0027re back to continue our discussion of the components of the blood."},{"Start":"00:05.980 ","End":"00:10.655","Text":"We\u0027ve been talking about these different cells that are in the blood,"},{"Start":"00:10.655 ","End":"00:12.810","Text":"we discussed red blood cells,"},{"Start":"00:12.810 ","End":"00:16.220","Text":"and then we discussed the white blood cells"},{"Start":"00:16.220 ","End":"00:20.115","Text":"and we said there are many different kinds of white blood cells."},{"Start":"00:20.115 ","End":"00:24.780","Text":"Now what we\u0027re going to do is to concentrate on lymphocytes."},{"Start":"00:24.780 ","End":"00:29.820","Text":"Lymphocytes are the primary cells of the immune system and of course,"},{"Start":"00:29.820 ","End":"00:33.330","Text":"they\u0027re found in the circulation but they\u0027re also concentrated"},{"Start":"00:33.330 ","End":"00:36.840","Text":"in the central lymphoid organs such as the spleen,"},{"Start":"00:36.840 ","End":"00:39.165","Text":"the tonsils, and the lymph nodes."},{"Start":"00:39.165 ","End":"00:43.620","Text":"These are places where the immune system really is concentrated."},{"Start":"00:43.620 ","End":"00:46.590","Text":"There are 2 different, or actually,"},{"Start":"00:46.590 ","End":"00:50.585","Text":"3 different kinds of lymphocytes that we want to speak about."},{"Start":"00:50.585 ","End":"00:53.075","Text":"First, we\u0027ll talk about B cells."},{"Start":"00:53.075 ","End":"00:55.595","Text":"B cells destroy bacteria,"},{"Start":"00:55.595 ","End":"00:59.420","Text":"inactivate their toxins, and produce antibodies."},{"Start":"00:59.420 ","End":"01:05.780","Text":"The principal thing they do is they produce antibodies, the B cells,"},{"Start":"01:05.780 ","End":"01:12.530","Text":"the B lymphocytes, and therefore they participate in the process of humoral immunity,"},{"Start":"01:12.530 ","End":"01:14.760","Text":"that means chemical immunity."},{"Start":"01:14.760 ","End":"01:17.750","Text":"Next, let\u0027s look at T cells."},{"Start":"01:17.750 ","End":"01:20.300","Text":"T lymphocytes, what do they do?"},{"Start":"01:20.300 ","End":"01:21.830","Text":"They attack viruses, fungi,"},{"Start":"01:21.830 ","End":"01:24.560","Text":"bacteria transplanted cells, and cancer cells."},{"Start":"01:24.560 ","End":"01:27.725","Text":"How did they do that? They release toxins,"},{"Start":"01:27.725 ","End":"01:32.835","Text":"these T cells, that kill the infected cells."},{"Start":"01:32.835 ","End":"01:37.380","Text":"They participate in cellular immunity."},{"Start":"01:38.410 ","End":"01:43.085","Text":"Next, we\u0027ll look at natural killer cells."},{"Start":"01:43.085 ","End":"01:50.165","Text":"Natural killer cells attack a variety of infectious microbes and certain tumor cells."},{"Start":"01:50.165 ","End":"01:54.200","Text":"This is natural cytotoxicity."},{"Start":"01:54.200 ","End":"01:57.370","Text":"Again, look at the cancer cells,"},{"Start":"01:57.370 ","End":"02:01.805","Text":"different cancer cells are killed actually by the immune system,"},{"Start":"02:01.805 ","End":"02:05.390","Text":"mainly by the natural killer cells and"},{"Start":"02:05.390 ","End":"02:09.679","Text":"so they will also kill the cells that are infected,"},{"Start":"02:09.679 ","End":"02:12.955","Text":"similar to T cells."},{"Start":"02:12.955 ","End":"02:16.620","Text":"Now let\u0027s look for a moment at HIV."},{"Start":"02:16.620 ","End":"02:22.955","Text":"HIV is a virus and the way it works is it"},{"Start":"02:22.955 ","End":"02:29.270","Text":"directly targets T cells by gaining entry through receptors that are in there."},{"Start":"02:29.270 ","End":"02:35.390","Text":"What we\u0027re going to do now is look a little bit at how the virus became successful."},{"Start":"02:35.390 ","End":"02:39.775","Text":"It\u0027s target, as we said, are T cells."},{"Start":"02:39.775 ","End":"02:42.815","Text":"Once inside the cell,"},{"Start":"02:42.815 ","End":"02:47.735","Text":"HIV multiplies using the T cells own genetic machinery."},{"Start":"02:47.735 ","End":"02:50.375","Text":"That is common."},{"Start":"02:50.375 ","End":"02:57.315","Text":"That\u0027s very common that the virus DNA will enter a cell,"},{"Start":"02:57.315 ","End":"03:05.975","Text":"incorporate into a chromosomal DNA of the cell and it\u0027s called a provirus."},{"Start":"03:05.975 ","End":"03:09.815","Text":"When the HIV virus replicates,"},{"Start":"03:09.815 ","End":"03:16.250","Text":"it\u0027s transmitted directly from the infected T cell to macrophages because"},{"Start":"03:16.250 ","End":"03:20.600","Text":"the infected T cell then will produce new virus"},{"Start":"03:20.600 ","End":"03:25.595","Text":"and that new virus then can go into macrophages."},{"Start":"03:25.595 ","End":"03:29.165","Text":"The presence of HIV can remain unrecognized, therefore,"},{"Start":"03:29.165 ","End":"03:35.570","Text":"for an extensive period of time because it doesn\u0027t do much when it\u0027s just proviral DNA."},{"Start":"03:35.570 ","End":"03:44.750","Text":"The only later will there will be full-fledged active infection in which new virus is"},{"Start":"03:44.750 ","End":"03:54.470","Text":"produced and blebs off from the macrophages making new virus that can infect new cells."},{"Start":"03:54.470 ","End":"03:58.640","Text":"Let\u0027s next look at platelets and coagulation factors."},{"Start":"03:58.640 ","End":"04:03.320","Text":"These are other cells that are inside the blood and of course,"},{"Start":"04:03.320 ","End":"04:06.275","Text":"when there is damage to blood vessels,"},{"Start":"04:06.275 ","End":"04:09.590","Text":"blood will leak out and that can be lethal."},{"Start":"04:09.590 ","End":"04:13.790","Text":"The blood must clot in order to heal"},{"Start":"04:13.790 ","End":"04:18.410","Text":"these wounds to stop the bleeding and prevent excess blood loss."},{"Start":"04:18.410 ","End":"04:24.050","Text":"This is done primarily by platelets or sometimes they\u0027re called thrombocytes."},{"Start":"04:24.050 ","End":"04:28.205","Text":"These are small cell fragments that are attracted to the wound site."},{"Start":"04:28.205 ","End":"04:36.995","Text":"They adhere there by extending projections and they release their contents into the area."},{"Start":"04:36.995 ","End":"04:43.670","Text":"That activates other platelets and then interacts with other coagulation factors,"},{"Start":"04:43.670 ","End":"04:48.470","Text":"different proteins which converts a protein called fibrinogen,"},{"Start":"04:48.470 ","End":"04:52.010","Text":"which is water-soluble into fibrin is"},{"Start":"04:52.010 ","End":"04:57.420","Text":"a chemical reaction there which makes a non-water, non-soluble protein."},{"Start":"04:57.420 ","End":"05:02.340","Text":"That then will stop the blood from moving."},{"Start":"05:02.340 ","End":"05:06.725","Text":"It causes the blood to clot into something called a thrombus,"},{"Start":"05:06.725 ","End":"05:08.480","Text":"which is the clot."},{"Start":"05:08.480 ","End":"05:15.935","Text":"There are actually lots of clotting factors and many of them require vitamin K to work."},{"Start":"05:15.935 ","End":"05:21.520","Text":"Vitamin K deficiency can lead to problems with blood clotting."},{"Start":"05:21.520 ","End":"05:25.190","Text":"Many platelets then will converge and"},{"Start":"05:25.190 ","End":"05:29.165","Text":"stick together forming some sort of a platelet plug."},{"Start":"05:29.165 ","End":"05:37.080","Text":"Yes, and that can last for several days to stop the loss of blood until healing occurs."},{"Start":"05:37.080 ","End":"05:46.365","Text":"The platelet life-cycle then starts from the disintegration of the megakaryocytes."},{"Start":"05:46.365 ","End":"05:52.535","Text":"You can see these large cells which then bleb off into these platelets."},{"Start":"05:52.535 ","End":"06:00.300","Text":"From each megakaryocyte, as many as 2,000-5,000 platelets are formed"},{"Start":"06:00.300 ","End":"06:08.705","Text":"and 150,000-400,000 platelets may be present in each cubic millimeter of blood."},{"Start":"06:08.705 ","End":"06:11.795","Text":"It\u0027s extremely concentrated,"},{"Start":"06:11.795 ","End":"06:15.125","Text":"these platelets so they can stop bleeding."},{"Start":"06:15.125 ","End":"06:16.610","Text":"Of course, it\u0027s extremely important,"},{"Start":"06:16.610 ","End":"06:21.035","Text":"each platelet is a disk which is only about 2-4 microns in diameter"},{"Start":"06:21.035 ","End":"06:26.275","Text":"and it may contain very small vesicles inside but"},{"Start":"06:26.275 ","End":"06:31.250","Text":"there\u0027s not a nucleus because it\u0027s blebbed off from the cell and"},{"Start":"06:31.250 ","End":"06:32.900","Text":"the human platelets can survive for"},{"Start":"06:32.900 ","End":"06:38.489","Text":"only about 10 days before they\u0027re removed from the bloodstream."}],"ID":30658},{"Watched":false,"Name":"Serum and Plasma and Blood Types","Duration":"8m 14s","ChapterTopicVideoID":29064,"CourseChapterTopicPlaylistID":294420,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.035","Text":"Until now when we\u0027ve been discussing the components of the blood,"},{"Start":"00:04.035 ","End":"00:06.840","Text":"we\u0027ve been discussing the solid components,"},{"Start":"00:06.840 ","End":"00:09.480","Text":"that is the blood cells,"},{"Start":"00:09.480 ","End":"00:11.295","Text":"the white blood cells,"},{"Start":"00:11.295 ","End":"00:15.074","Text":"and the red blood cells as well as the platelets."},{"Start":"00:15.074 ","End":"00:21.915","Text":"Now, let\u0027s look at the liquid which forms on top if we centrifuge some blood."},{"Start":"00:21.915 ","End":"00:23.205","Text":"What\u0027s that got in it?"},{"Start":"00:23.205 ","End":"00:27.370","Text":"It\u0027s about 55 percent of the blood."},{"Start":"00:28.820 ","End":"00:32.955","Text":"It is about 90 percent water along"},{"Start":"00:32.955 ","End":"00:37.124","Text":"with other substances that are required for maintaining the body\u0027s pH,"},{"Start":"00:37.124 ","End":"00:39.290","Text":"it\u0027s asthmatic load in protection."},{"Start":"00:39.290 ","End":"00:40.640","Text":"It\u0027s got water, proteins,"},{"Start":"00:40.640 ","End":"00:43.190","Text":"nutrients, salts, metabolites, enzymes,"},{"Start":"00:43.190 ","End":"00:45.785","Text":"hormones in it for instance,"},{"Start":"00:45.785 ","End":"00:50.480","Text":"as well as coagulation factors and antibodies."},{"Start":"00:50.480 ","End":"00:55.265","Text":"Now, you know that there is something else besides plasma."},{"Start":"00:55.265 ","End":"00:58.204","Text":"There\u0027s something called serum."},{"Start":"00:58.204 ","End":"01:00.535","Text":"What is serum?"},{"Start":"01:00.535 ","End":"01:08.570","Text":"If we form a blood clot of the blood and we look to see what\u0027s left,"},{"Start":"01:08.570 ","End":"01:10.400","Text":"then we get serum."},{"Start":"01:10.400 ","End":"01:15.080","Text":"The serum is the plasma component without"},{"Start":"01:15.080 ","End":"01:20.875","Text":"the coagulation factors that caused the blood clot."},{"Start":"01:20.875 ","End":"01:23.780","Text":"What does it contain? Well, it"},{"Start":"01:23.780 ","End":"01:26.780","Text":"contains of course the proteins that assist with maintaining"},{"Start":"01:26.780 ","End":"01:28.670","Text":"the pH with the buffering and"},{"Start":"01:28.670 ","End":"01:32.375","Text":"the osmotic balance while giving the viscosity to the blood."},{"Start":"01:32.375 ","End":"01:35.760","Text":"It also contains antibodies,"},{"Start":"01:35.760 ","End":"01:38.240","Text":"immunoglobulins, they\u0027re called sometimes,"},{"Start":"01:38.240 ","End":"01:40.760","Text":"which are the proteins that are used by the immune system to"},{"Start":"01:40.760 ","End":"01:44.360","Text":"identify and neutralize foreign substances,"},{"Start":"01:44.360 ","End":"01:47.210","Text":"as well as lipids like cholesterol,"},{"Start":"01:47.210 ","End":"01:51.995","Text":"which are transported in the serum along with other substances like nutrients, hormones,"},{"Start":"01:51.995 ","End":"01:57.695","Text":"and metabolic waste as well as sugar actually."},{"Start":"01:57.695 ","End":"02:02.370","Text":"Now, we said that there are proteins in the blood."},{"Start":"02:02.370 ","End":"02:07.385","Text":"One of the major proteins is called serum albumin."},{"Start":"02:07.385 ","End":"02:10.040","Text":"If it\u0027s human then its human serum albumin."},{"Start":"02:10.040 ","End":"02:13.310","Text":"It\u0027s a very large protein component of the blood."},{"Start":"02:13.310 ","End":"02:16.525","Text":"It makes up about 50-60 percent."},{"Start":"02:16.525 ","End":"02:20.750","Text":"It\u0027s an important factor in the regulation of the volume of the blood"},{"Start":"02:20.750 ","End":"02:25.790","Text":"even is so much of it and the tissue fluid balance."},{"Start":"02:25.790 ","End":"02:30.925","Text":"It\u0027s synthesized in the liver and transports"},{"Start":"02:30.925 ","End":"02:36.275","Text":"hormones and fatty acids besides the buffering and maintaining of the osmotic pressure."},{"Start":"02:36.275 ","End":"02:42.815","Text":"It\u0027s often used to replace lost fluid and can help restore blood volume in trauma,"},{"Start":"02:42.815 ","End":"02:46.264","Text":"burn patients and surgery patients."},{"Start":"02:46.264 ","End":"02:54.665","Text":"Serum albumin human is a very important protein that is very abundant."},{"Start":"02:54.665 ","End":"02:57.200","Text":"Now let\u0027s look at blood types."},{"Start":"02:57.200 ","End":"03:03.770","Text":"We mentioned this a little bit before that there are blood types of A,"},{"Start":"03:03.770 ","End":"03:09.480","Text":"B, AB, and O, as well as Rh."},{"Start":"03:09.480 ","End":"03:13.445","Text":"What is that about? They define"},{"Start":"03:13.445 ","End":"03:18.400","Text":"the glycoproteins that are on the outside of red blood cells."},{"Start":"03:18.400 ","End":"03:22.280","Text":"In humans, the different surface antigens are grouped into"},{"Start":"03:22.280 ","End":"03:29.635","Text":"24 different blood groups with more than 100 different antigens on each red blood cell."},{"Start":"03:29.635 ","End":"03:32.900","Text":"That\u0027s an addition to these antigens,"},{"Start":"03:32.900 ","End":"03:34.490","Text":"an addition to these glycoproteins."},{"Start":"03:34.490 ","End":"03:36.605","Text":"There are a lot of others as well,"},{"Start":"03:36.605 ","End":"03:42.725","Text":"but the main ones are discussed here in the ABO group,"},{"Start":"03:42.725 ","End":"03:44.570","Text":"the well known blood groups,"},{"Start":"03:44.570 ","End":"03:47.600","Text":"and of course there\u0027s the Rh system."},{"Start":"03:47.600 ","End":"03:54.230","Text":"Let\u0027s review again what the ABO blood groups mean and they denote, as I just said,"},{"Start":"03:54.230 ","End":"03:55.250","Text":"the presence of 1,"},{"Start":"03:55.250 ","End":"03:58.559","Text":"both or either of the A and B glycoproteins,"},{"Start":"03:58.559 ","End":"04:00.905","Text":"these antigens on erythrocytes."},{"Start":"04:00.905 ","End":"04:03.680","Text":"We call them antigens here because we\u0027re going to be"},{"Start":"04:03.680 ","End":"04:07.420","Text":"discussing them in the context of antibodies."},{"Start":"04:07.420 ","End":"04:14.222","Text":"Here you can see the different antigens on the outside of A and B erythrocytes."},{"Start":"04:14.222 ","End":"04:15.350","Text":"Here we\u0027ve got both of them."},{"Start":"04:15.350 ","End":"04:17.120","Text":"In type O, we have none of them."},{"Start":"04:17.120 ","End":"04:22.580","Text":"Now people that have one blood type,"},{"Start":"04:22.580 ","End":"04:27.740","Text":"in addition to the antigens which are on the outside of the cells,"},{"Start":"04:27.740 ","End":"04:33.005","Text":"there are antibodies against the other antigen."},{"Start":"04:33.005 ","End":"04:36.260","Text":"In this case, for instance in type B cells,"},{"Start":"04:36.260 ","End":"04:43.935","Text":"we have antibodies that are against the anti-A antibodies."},{"Start":"04:43.935 ","End":"04:47.385","Text":"Whereas in type A cells,"},{"Start":"04:47.385 ","End":"04:51.700","Text":"we\u0027re going to have antibodies that are anti-B."},{"Start":"04:51.700 ","End":"04:55.190","Text":"Of course, in type O cells,"},{"Start":"04:55.190 ","End":"04:58.970","Text":"we\u0027ll have antibodies against both as you can see"},{"Start":"04:58.970 ","End":"05:04.355","Text":"here on the right but in type AB cells,"},{"Start":"05:04.355 ","End":"05:11.180","Text":"we have neither anti-A nor anti-B antibodies."},{"Start":"05:11.180 ","End":"05:15.290","Text":"When type A and type B blood are combined,"},{"Start":"05:15.290 ","End":"05:17.765","Text":"like we can see here,"},{"Start":"05:17.765 ","End":"05:21.665","Text":"then what happens is we get agglutination,"},{"Start":"05:21.665 ","End":"05:27.560","Text":"clumping of the blood because the plasma antibodies bind with the opposing antigen making"},{"Start":"05:27.560 ","End":"05:30.550","Text":"the blood cells stick to each other and that"},{"Start":"05:30.550 ","End":"05:34.700","Text":"causes clots that coagulate in the kidney and cause kidney failure."},{"Start":"05:34.700 ","End":"05:36.320","Text":"That\u0027s bad news."},{"Start":"05:36.320 ","End":"05:40.765","Text":"We don\u0027t want to mix other bloods in together."},{"Start":"05:40.765 ","End":"05:44.780","Text":"The best blood for transfusions for instance would"},{"Start":"05:44.780 ","End":"05:49.235","Text":"be type blood O that has neither A or B antigens."},{"Start":"05:49.235 ","End":"05:55.645","Text":"Therefore type O blood can be given to all blood types without causing the type of"},{"Start":"05:55.645 ","End":"06:03.560","Text":"coagulation and therefore type O blood is called the universal donor blood."},{"Start":"06:03.560 ","End":"06:08.075","Text":"The type AB positive blood is universal acceptor."},{"Start":"06:08.075 ","End":"06:12.520","Text":"In other words, somebody who has AB positive blood can get"},{"Start":"06:12.520 ","End":"06:21.110","Text":"blood transfusions from anybody because it has both the A and B antigens."},{"Start":"06:21.110 ","End":"06:23.975","Text":"Now in addition to the AB blood groups,"},{"Start":"06:23.975 ","End":"06:27.560","Text":"there is also the issue of Rh."},{"Start":"06:27.560 ","End":"06:32.405","Text":"It\u0027s called Rh because it was first discovered in these Rhesus monkeys."},{"Start":"06:32.405 ","End":"06:35.330","Text":"It\u0027s another blood protein."},{"Start":"06:35.330 ","End":"06:37.640","Text":"Most people have the Rh antigen."},{"Start":"06:37.640 ","End":"06:44.045","Text":"They\u0027re called Rh plus and therefore they don\u0027t have anti Rh antibodies in their blood."},{"Start":"06:44.045 ","End":"06:48.100","Text":"However, there is one case which can be dangerous,"},{"Start":"06:48.100 ","End":"06:54.515","Text":"and that is the case where you have a woman who\u0027s pregnant who is"},{"Start":"06:54.515 ","End":"07:02.750","Text":"Rh negative but the father is Rh positive."},{"Start":"07:02.750 ","End":"07:12.620","Text":"You can see the father is Rh positive and the mother is Rh negative. Then what"},{"Start":"07:12.620 ","End":"07:14.915","Text":"will happen is that a little bit of"},{"Start":"07:14.915 ","End":"07:19.220","Text":"the baby\u0027s blood might get into her bloodstream and she\u0027ll develop antibodies."},{"Start":"07:19.220 ","End":"07:22.950","Text":"Then on the next pregnancy,"},{"Start":"07:24.710 ","End":"07:30.875","Text":"if she\u0027s pregnant again with Rh positive fetus,"},{"Start":"07:30.875 ","End":"07:33.425","Text":"because the father is Rh positive,"},{"Start":"07:33.425 ","End":"07:39.080","Text":"then those antibodies might attack the baby or they can cross"},{"Start":"07:39.080 ","End":"07:44.900","Text":"the placenta and damage the fetal blood cells and that can be a very damaging thing."},{"Start":"07:44.900 ","End":"07:49.550","Text":"It\u0027s important to note what the situation here is and take"},{"Start":"07:49.550 ","End":"07:54.710","Text":"note of it during the pregnancy of Rh negative women."},{"Start":"07:54.710 ","End":"07:59.240","Text":"This can happen as well if a woman or a person actually is"},{"Start":"07:59.240 ","End":"08:06.780","Text":"an Rh negative person and gets a transfusion from an Rh plus person."},{"Start":"08:06.780 ","End":"08:11.150","Text":"That\u0027s something that has to be cared for as well as what I just discussed,"},{"Start":"08:11.150 ","End":"08:14.310","Text":"having an Rh plus baby."}],"ID":30659}],"Thumbnail":null,"ID":294420},{"Name":"Mammalian Heart and Blood Vessels","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Blood Flow Fhrough the Heart","Duration":"9m 23s","ChapterTopicVideoID":29058,"CourseChapterTopicPlaylistID":294421,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.160","Text":"I\u0027m really glad that you\u0027re back to discuss blood vessels."},{"Start":"00:05.160 ","End":"00:09.090","Text":"How blood moves now through the body."},{"Start":"00:09.090 ","End":"00:12.390","Text":"We have discussed the gas exchange and"},{"Start":"00:12.390 ","End":"00:16.560","Text":"nutrient exchange and waste exchange in and out of the blood."},{"Start":"00:16.560 ","End":"00:22.980","Text":"We\u0027ve discussed different blood cells and now it\u0027s time for us to discuss"},{"Start":"00:22.980 ","End":"00:30.840","Text":"in mammals how the blood actually moves through the body."},{"Start":"00:30.840 ","End":"00:34.770","Text":"We know that organisms that have high metabolic rates need"},{"Start":"00:34.770 ","End":"00:40.650","Text":"a very efficient way to deliver oxygen to the cells around their body."},{"Start":"00:40.650 ","End":"00:43.620","Text":"We\u0027ve discussed this a little bit before."},{"Start":"00:43.620 ","End":"00:50.085","Text":"If you remember, we\u0027ve discussed what the blood system looks like and"},{"Start":"00:50.085 ","End":"00:53.280","Text":"we\u0027ve looked at diagrams similar to this and"},{"Start":"00:53.280 ","End":"00:56.790","Text":"you\u0027ll remember that in some of the more primitive hearts,"},{"Start":"00:56.790 ","End":"01:01.965","Text":"there was mixing of oxygenated and non-oxygenated blood."},{"Start":"01:01.965 ","End":"01:07.770","Text":"But in mammalian systems there is not this mixing."},{"Start":"01:07.770 ","End":"01:14.340","Text":"That\u0027s because we have this double circulatory system."},{"Start":"01:14.340 ","End":"01:20.070","Text":"A double circulatory system which both mammals and birds have,"},{"Start":"01:20.070 ","End":"01:25.755","Text":"which allows oxygenated and deoxygenated blood to flow separately."},{"Start":"01:25.755 ","End":"01:32.400","Text":"That is, they don\u0027t mix inside the heart and this complete double circulatory system"},{"Start":"01:32.400 ","End":"01:39.930","Text":"allows for the high metabolic rates that we find in both mammals and birds."},{"Start":"01:39.930 ","End":"01:43.395","Text":"How does this work? First of all,"},{"Start":"01:43.395 ","End":"01:53.130","Text":"the circulatory system is divided actually into 3 different systems."},{"Start":"01:53.130 ","End":"01:56.145","Text":"We have, of course, the systemic,"},{"Start":"01:56.145 ","End":"02:04.575","Text":"that is the blood which is moving into the system, into our tissues."},{"Start":"02:04.575 ","End":"02:06.330","Text":"We have the pulmonary,"},{"Start":"02:06.330 ","End":"02:13.275","Text":"that is how the blood gets oxygenated and moves into our lungs."},{"Start":"02:13.275 ","End":"02:14.790","Text":"But in addition to that,"},{"Start":"02:14.790 ","End":"02:19.020","Text":"we also have a coronary system."},{"Start":"02:19.020 ","End":"02:25.485","Text":"That is how the blood oxygenates the heart itself."},{"Start":"02:25.485 ","End":"02:29.865","Text":"We have these coronary vessels that serve the heart."},{"Start":"02:29.865 ","End":"02:32.145","Text":"We have the pulmonary ones,"},{"Start":"02:32.145 ","End":"02:35.010","Text":"which serve primarily the lungs,"},{"Start":"02:35.010 ","End":"02:38.790","Text":"but also the heart to some extent and we have this systemic,"},{"Start":"02:38.790 ","End":"02:40.680","Text":"as we mentioned before,"},{"Start":"02:40.680 ","End":"02:46.110","Text":"which oxygenates or brings blood to the rest of the body."},{"Start":"02:46.110 ","End":"02:52.770","Text":"Now, the coronary circulation takes blood directly from the aorta."},{"Start":"02:52.770 ","End":"02:54.480","Text":"We\u0027re going to see this,"},{"Start":"02:54.480 ","End":"02:56.205","Text":"this is going to be the aorta."},{"Start":"02:56.205 ","End":"03:00.585","Text":"It\u0027s where the oxygenated blood comes out of the heart and then"},{"Start":"03:00.585 ","End":"03:05.175","Text":"it takes it directly to the heart."},{"Start":"03:05.175 ","End":"03:07.770","Text":"This is a schematic picture."},{"Start":"03:07.770 ","End":"03:12.960","Text":"We\u0027re talking about the blood vessels that are in the heart itself."},{"Start":"03:12.960 ","End":"03:15.855","Text":"For pulmonary and systemic circulation,"},{"Start":"03:15.855 ","End":"03:17.400","Text":"the heart of course,"},{"Start":"03:17.400 ","End":"03:24.045","Text":"pumps the blood away from the heart itself to either the lungs or the rest of the body."},{"Start":"03:24.045 ","End":"03:29.340","Text":"Now let\u0027s look at the structure of the heart in a more detailed fashion."},{"Start":"03:29.340 ","End":"03:31.740","Text":"Of course, as we mentioned before,"},{"Start":"03:31.740 ","End":"03:36.072","Text":"we don\u0027t have mixing of the blood and in these pictures,"},{"Start":"03:36.072 ","End":"03:40.020","Text":"we\u0027ll see oxygenated vessels as being in"},{"Start":"03:40.020 ","End":"03:47.730","Text":"a red color and deoxygenated blood vessels with carrying deoxygenated blood in blue."},{"Start":"03:47.730 ","End":"03:54.600","Text":"The blue is carrying deoxygenated and the red is carrying oxygenated."},{"Start":"03:54.600 ","End":"04:02.085","Text":"We mentioned a minute ago that we have these pulmonary systems and we have"},{"Start":"04:02.085 ","End":"04:06.750","Text":"the systemic systems and"},{"Start":"04:06.750 ","End":"04:12.435","Text":"we have the coronary systems."},{"Start":"04:12.435 ","End":"04:15.600","Text":"Each of these are not necessarily the same distance away."},{"Start":"04:15.600 ","End":"04:18.585","Text":"Of course, the coronary system is going to be in the heart itself."},{"Start":"04:18.585 ","End":"04:23.490","Text":"The pulmonary to the lungs is lot closer than the systemic,"},{"Start":"04:23.490 ","End":"04:27.420","Text":"let\u0027s say the ends of the body and therefore,"},{"Start":"04:27.420 ","End":"04:30.090","Text":"the heart muscle is asymmetrical."},{"Start":"04:30.090 ","End":"04:33.255","Text":"Because the distance the blood must travel is"},{"Start":"04:33.255 ","End":"04:37.290","Text":"different in the pulmonary and systemic circuits."},{"Start":"04:37.290 ","End":"04:39.900","Text":"It turns out that the right side,"},{"Start":"04:39.900 ","End":"04:43.545","Text":"this is now as we are facing forward,"},{"Start":"04:43.545 ","End":"04:46.305","Text":"so the right side of our body in these pictures,"},{"Start":"04:46.305 ","End":"04:49.650","Text":"the picture we\u0027re looking at the heart from the front."},{"Start":"04:49.650 ","End":"04:53.070","Text":"What\u0027s on the right is on the left of"},{"Start":"04:53.070 ","End":"04:58.560","Text":"our diagram and what\u0027s on the left of the heart will be on the right of our diagram."},{"Start":"04:58.560 ","End":"05:03.450","Text":"The right side is going to be sending"},{"Start":"05:03.450 ","End":"05:06.450","Text":"blood to the pulmonary circuit and therefore"},{"Start":"05:06.450 ","End":"05:09.435","Text":"it\u0027s going to be smaller than the left side,"},{"Start":"05:09.435 ","End":"05:13.530","Text":"which is sending blood to the rest of our body."},{"Start":"05:13.530 ","End":"05:18.750","Text":"In humans, the heart is about the size of a clenched fist."},{"Start":"05:18.750 ","End":"05:21.240","Text":"If you close your fist and look at it,"},{"Start":"05:21.240 ","End":"05:23.865","Text":"you\u0027ll see about what the size of the heart is, pretty big."},{"Start":"05:23.865 ","End":"05:29.835","Text":"It weighs about 300 grams and consists of 4 chambers."},{"Start":"05:29.835 ","End":"05:33.765","Text":"Actually, there\u0027ll be 2 atria."},{"Start":"05:33.765 ","End":"05:38.145","Text":"That\u0027s the going to be the area where the blood is going to first come into the heart"},{"Start":"05:38.145 ","End":"05:43.110","Text":"and then 2 ventricles that are going to pump the blood out."},{"Start":"05:43.110 ","End":"05:46.290","Text":"Here you can see there this left ventricle and right"},{"Start":"05:46.290 ","End":"05:51.270","Text":"ventricles and there is the left atrium on the top and"},{"Start":"05:51.270 ","End":"06:00.090","Text":"the right atrium on the top that are going to be pumping the blood into the ventricles."},{"Start":"06:00.090 ","End":"06:06.555","Text":"There is 1 atrium and 1 ventricle on each side of the heart,"},{"Start":"06:06.555 ","End":"06:10.110","Text":"and they are separated by this septum,"},{"Start":"06:10.110 ","End":"06:13.600","Text":"which is right in the middle."},{"Start":"06:14.120 ","End":"06:17.925","Text":"Let\u0027s now look at it in greater detail."},{"Start":"06:17.925 ","End":"06:21.570","Text":"First, look at the blood vessels that are coming in and out of"},{"Start":"06:21.570 ","End":"06:26.040","Text":"the heart and we\u0027ll start with the superior vena cava."},{"Start":"06:26.040 ","End":"06:27.960","Text":"Superior vena cava,"},{"Start":"06:27.960 ","End":"06:30.690","Text":"notice it is blue."},{"Start":"06:30.690 ","End":"06:35.070","Text":"This drains blood from the jugular vein that comes from the brain."},{"Start":"06:35.070 ","End":"06:37.800","Text":"This is going to be blood that\u0027s coming from our head,"},{"Start":"06:37.800 ","End":"06:43.470","Text":"from our brain and the ones that are coming from the arms,"},{"Start":"06:43.470 ","End":"06:45.675","Text":"the superior vena cava."},{"Start":"06:45.675 ","End":"06:48.690","Text":"We also have the inferior vena cava."},{"Start":"06:48.690 ","End":"06:52.080","Text":"It\u0027ll be a smaller vein that drains blood that comes"},{"Start":"06:52.080 ","End":"06:57.150","Text":"from the lower organs in our abdomen and from our legs."},{"Start":"06:57.150 ","End":"07:00.735","Text":"In addition, there\u0027s a coronary sinus,"},{"Start":"07:00.735 ","End":"07:08.730","Text":"which is a space that drains deoxygenated blood from the heart itself."},{"Start":"07:08.730 ","End":"07:12.930","Text":"Now let\u0027s look for a moment at valves that are in the heart."},{"Start":"07:12.930 ","End":"07:17.040","Text":"Now, these are different valves that have different names."},{"Start":"07:17.040 ","End":"07:21.060","Text":"Notice there at the bottom of each of"},{"Start":"07:21.060 ","End":"07:26.910","Text":"these blood vessels and what they\u0027re going to be is unidirectional valves."},{"Start":"07:26.910 ","End":"07:31.740","Text":"That is valves that allow blood to move in only 1 direction."},{"Start":"07:31.740 ","End":"07:37.740","Text":"Remember, we have blood going from the atria into the ventricles."},{"Start":"07:37.740 ","End":"07:40.680","Text":"Those are going to be blood valves that are going to"},{"Start":"07:40.680 ","End":"07:45.030","Text":"allow movement in this direction down."},{"Start":"07:45.030 ","End":"07:48.375","Text":"Yes. Only in that direction and then there\u0027ll be"},{"Start":"07:48.375 ","End":"07:52.440","Text":"other valves that are going to allow blood out."},{"Start":"07:52.440 ","End":"07:55.710","Text":"This is moving into the aorta, for instance,"},{"Start":"07:55.710 ","End":"07:57.780","Text":"from the left ventricle,"},{"Start":"07:57.780 ","End":"08:02.430","Text":"this will be a valve which is unidirectional out."},{"Start":"08:02.430 ","End":"08:05.625","Text":"Then of course we have the pulmonary artery,"},{"Start":"08:05.625 ","End":"08:08.805","Text":"which is also going to be going out."},{"Start":"08:08.805 ","End":"08:10.995","Text":"Notice, it\u0027s blue because"},{"Start":"08:10.995 ","End":"08:14.190","Text":"this blood that\u0027s leaving the heart is going to be going towards the lungs."},{"Start":"08:14.190 ","End":"08:17.325","Text":"It\u0027s still the oxygenated."},{"Start":"08:17.325 ","End":"08:20.865","Text":"These valves, as I said, all have names."},{"Start":"08:20.865 ","End":"08:24.525","Text":"We have the atrioventricle valve,"},{"Start":"08:24.525 ","End":"08:27.570","Text":"which is a flap of connective tissue that opens only 1 direction,"},{"Start":"08:27.570 ","End":"08:31.020","Text":"prevents the backflow of de-oxygenated blood."},{"Start":"08:31.020 ","End":"08:35.730","Text":"Deoxygenated blood right from the right ventricle to the right atrium,"},{"Start":"08:35.730 ","End":"08:39.540","Text":"we have the bi cuspid or the mitral valve that"},{"Start":"08:39.540 ","End":"08:44.715","Text":"separates the atrium and the ventricle on the left side of the heart."},{"Start":"08:44.715 ","End":"08:48.330","Text":"Sometimes there are leakages here that can cause problems."},{"Start":"08:48.330 ","End":"08:50.730","Text":"Notice this is a bicuspid valve."},{"Start":"08:50.730 ","End":"08:52.905","Text":"It\u0027s only got 2 flaps."},{"Start":"08:52.905 ","End":"08:56.235","Text":"All the others have 3, check tricuspid."},{"Start":"08:56.235 ","End":"09:00.625","Text":"Then we have the semi-lunar or the pulmonic valve."},{"Start":"09:00.625 ","End":"09:04.560","Text":"That\u0027s going to prevent the oxygenated blood from flowing backward"},{"Start":"09:04.560 ","End":"09:08.595","Text":"from the pulmonary artery back into the ventricle."},{"Start":"09:08.595 ","End":"09:10.740","Text":"And we have the aortic,"},{"Start":"09:10.740 ","End":"09:14.760","Text":"semilunar aortic valve that we can see here,"},{"Start":"09:14.760 ","End":"09:17.940","Text":"which is going to preventing blood from flowing backward"},{"Start":"09:17.940 ","End":"09:23.920","Text":"into the left ventricle from the aorta in a similar fashion."}],"ID":30640},{"Watched":false,"Name":"Layers of Heart Tissue, Pulmonary Circulation and Heart Attack","Duration":"5m 19s","ChapterTopicVideoID":29059,"CourseChapterTopicPlaylistID":294421,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.475","Text":"I\u0027m glad that you\u0027re back now to continue our discussion of the mammalian heart."},{"Start":"00:05.475 ","End":"00:09.540","Text":"We discussed in the previous video the structure of the heart in general,"},{"Start":"00:09.540 ","End":"00:11.370","Text":"the how the blood flows around it."},{"Start":"00:11.370 ","End":"00:15.780","Text":"Now let\u0027s look at the muscle lobe in a little bit more detail."},{"Start":"00:15.780 ","End":"00:20.805","Text":"The wall of the heart has several layers,"},{"Start":"00:20.805 ","End":"00:22.860","Text":"they are the epicardium,"},{"Start":"00:22.860 ","End":"00:26.865","Text":"the myocardium, that\u0027s the muscle that\u0027s in the middle."},{"Start":"00:26.865 ","End":"00:29.685","Text":"The thick muscular layer,"},{"Start":"00:29.685 ","End":"00:31.710","Text":"and we have the endocardium,"},{"Start":"00:31.710 ","End":"00:33.905","Text":"that\u0027s the inner layer."},{"Start":"00:33.905 ","End":"00:38.135","Text":"That\u0027s the area that\u0027s going to be touching the blood on the inside of"},{"Start":"00:38.135 ","End":"00:43.370","Text":"the chambers of the heart."},{"Start":"00:43.370 ","End":"00:47.580","Text":"We\u0027ve got the epicardium on the outside,"},{"Start":"00:48.830 ","End":"00:54.005","Text":"we have the myocardium in the middle,"},{"Start":"00:54.005 ","End":"01:00.710","Text":"and we have the endocardium that is going to be on the inside."},{"Start":"01:00.710 ","End":"01:07.565","Text":"In addition, we have a pericardial sac on the outside of the heart."},{"Start":"01:07.565 ","End":"01:14.195","Text":"We going to have some tissue which is going to keep the heart intact and its shape."},{"Start":"01:14.195 ","End":"01:18.350","Text":"It\u0027s a connective layer of tissue that encompasses all of"},{"Start":"01:18.350 ","End":"01:22.520","Text":"the heart and it consists of a fibrous material,"},{"Start":"01:22.520 ","End":"01:28.130","Text":"the outer layer, and something called a serous pericardium."},{"Start":"01:28.130 ","End":"01:30.560","Text":"It\u0027s an inner double layer of membrane."},{"Start":"01:30.560 ","End":"01:35.405","Text":"Any case, it\u0027s a tough membrane that keeps the heart contained in the chest cavity."},{"Start":"01:35.405 ","End":"01:37.745","Text":"It prevents it from overextending."},{"Start":"01:37.745 ","End":"01:39.860","Text":"Like when the blood volume increases,"},{"Start":"01:39.860 ","End":"01:44.465","Text":"the heart has to stay the same size so that it can pump out."},{"Start":"01:44.465 ","End":"01:47.330","Text":"It also reduces friction of the heart and the surrounding tissues."},{"Start":"01:47.330 ","End":"01:50.345","Text":"Of course, the heart is moving very quickly"},{"Start":"01:50.345 ","End":"01:54.763","Text":"and it would not be good if there were a lot of friction,"},{"Start":"01:54.763 ","End":"02:02.134","Text":"has to slide past the other tissues around it and it protects it against infection."},{"Start":"02:02.134 ","End":"02:07.325","Text":"In fact, sometimes there is a pericardium infection and"},{"Start":"02:07.325 ","End":"02:13.145","Text":"that\u0027s a heart infection that can be fatal if it\u0027s not taken care of."},{"Start":"02:13.145 ","End":"02:15.735","Text":"Now, the heart as we said,"},{"Start":"02:15.735 ","End":"02:18.275","Text":"of course, needs its own blood supply."},{"Start":"02:18.275 ","End":"02:22.048","Text":"That blood supply does not come from within the heart,"},{"Start":"02:22.048 ","End":"02:25.220","Text":"it comes from that coronary system that we talked about in"},{"Start":"02:25.220 ","End":"02:30.860","Text":"the last video where we have an artery that comes out of"},{"Start":"02:30.860 ","End":"02:34.850","Text":"the aorta and then divides into"},{"Start":"02:34.850 ","End":"02:40.850","Text":"smaller blood vessels that bring blood to the various parts of the heart."},{"Start":"02:40.850 ","End":"02:45.170","Text":"Of course, the heart muscle will die if it doesn\u0027t have a steady supply of blood,"},{"Start":"02:45.170 ","End":"02:47.630","Text":"just like any other tissue,"},{"Start":"02:47.630 ","End":"02:52.340","Text":"and it\u0027s the particular coordinate system that brings this blood."},{"Start":"02:52.340 ","End":"02:55.790","Text":"There are branches in this system, as we said,"},{"Start":"02:55.790 ","End":"02:58.130","Text":"it comes from the aorta initially,"},{"Start":"02:58.130 ","End":"03:01.250","Text":"and it surrounds the outer area."},{"Start":"03:01.250 ","End":"03:03.200","Text":"It looks a little bit like a crown maybe."},{"Start":"03:03.200 ","End":"03:07.850","Text":"These are called coronary arteries that supply the muscle with oxygenated blood."},{"Start":"03:07.850 ","End":"03:13.640","Text":"Then, of course, there are coronary veins that are not shown really in this."},{"Start":"03:13.640 ","End":"03:19.280","Text":"Well, actually these are the coronary veins which then return blood that"},{"Start":"03:19.280 ","End":"03:25.100","Text":"is deoxygenated back into the heart,"},{"Start":"03:25.100 ","End":"03:27.320","Text":"so into the right atrium."},{"Start":"03:27.320 ","End":"03:34.415","Text":"In some cases, these blood vessels can become a little bit clogged,"},{"Start":"03:34.415 ","End":"03:36.290","Text":"there can be some blockage,"},{"Start":"03:36.290 ","End":"03:43.220","Text":"it\u0027s called atherosclerosis, and that is the buildup of plaques."},{"Start":"03:43.220 ","End":"03:47.390","Text":"Sometimes there are often made of cholesterol in which the arteries"},{"Start":"03:47.390 ","End":"03:52.360","Text":"become blocked and they become more and more blocked."},{"Start":"03:52.360 ","End":"03:56.825","Text":"Because these arteries are relatively narrow,"},{"Start":"03:56.825 ","End":"03:59.485","Text":"this can be deadly."},{"Start":"03:59.485 ","End":"04:01.920","Text":"We\u0027re talking about a heart attack here."},{"Start":"04:01.920 ","End":"04:04.675","Text":"We\u0027re talking about a heart attack in which"},{"Start":"04:04.675 ","End":"04:08.065","Text":"the blood supply to the heart is insufficient,"},{"Start":"04:08.065 ","End":"04:13.600","Text":"and in fact, you can get complete blockage which is called angina pectoris."},{"Start":"04:13.600 ","End":"04:16.720","Text":"You get this terrible chest pain, discomfort,"},{"Start":"04:16.720 ","End":"04:20.350","Text":"sometimes it\u0027s called people report that it feels like pressure,"},{"Start":"04:20.350 ","End":"04:22.790","Text":"squeezing, or burning or fullness,"},{"Start":"04:22.790 ","End":"04:25.750","Text":"there are different feelings of this,"},{"Start":"04:25.750 ","End":"04:32.980","Text":"but it\u0027s because there is not sufficient oxygen getting to the heart muscle and we"},{"Start":"04:32.980 ","End":"04:40.345","Text":"can get what\u0027s called a myocardial infarction that is death of cardiac muscle."},{"Start":"04:40.345 ","End":"04:45.440","Text":"That\u0027s the heart attack in which we have complete blockage of coronary arteries,"},{"Start":"04:45.440 ","End":"04:48.560","Text":"of course, that can cause a lot of damage to the heart."},{"Start":"04:48.560 ","End":"04:50.810","Text":"If there is too much damage,"},{"Start":"04:50.810 ","End":"04:54.530","Text":"it can stop pumping and we get a death."},{"Start":"04:54.530 ","End":"04:58.400","Text":"Here you can see a sort of an enlarged picture of how"},{"Start":"04:58.400 ","End":"05:04.585","Text":"this plaque buildup can cause the blood from not flowing as it should."},{"Start":"05:04.585 ","End":"05:06.305","Text":"Here you can see it returning."},{"Start":"05:06.305 ","End":"05:12.095","Text":"There could be a thrombus or a blood clot which is formed inside this artery"},{"Start":"05:12.095 ","End":"05:19.110","Text":"causing this myocardial infarction or a heart attack."}],"ID":30641},{"Watched":false,"Name":"The Heart Pumping Cycle","Duration":"6m 49s","ChapterTopicVideoID":29060,"CourseChapterTopicPlaylistID":294421,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.765","Text":"Now, continuing our discussion of the mammalian heart,"},{"Start":"00:03.765 ","End":"00:11.475","Text":"we discussed its structure and what happens if there\u0027s a myocardial infarction that is,"},{"Start":"00:11.475 ","End":"00:14.520","Text":"that the blood doesn\u0027t get to all the heart,"},{"Start":"00:14.520 ","End":"00:16.425","Text":"and of course, it\u0027s a heart attack and damage."},{"Start":"00:16.425 ","End":"00:21.029","Text":"Let\u0027s now look at what happens when it\u0027s beating properly."},{"Start":"00:21.029 ","End":"00:23.355","Text":"So there is a cardiac cycle,"},{"Start":"00:23.355 ","End":"00:27.525","Text":"there\u0027s a repeating sequence of blood pumping by the heart."},{"Start":"00:27.525 ","End":"00:29.430","Text":"The human heart, of course,"},{"Start":"00:29.430 ","End":"00:35.400","Text":"beats throughout the lifetime and it beats over a 100,000 times per day."},{"Start":"00:35.400 ","End":"00:40.015","Text":"It comes out to about 3 billion times during a lifetime,"},{"Start":"00:40.015 ","End":"00:44.290","Text":"that\u0027s an awful lot of beating, I would say."},{"Start":"00:44.480 ","End":"00:49.250","Text":"Of course this beating has to be coordinated by electrical signals that"},{"Start":"00:49.250 ","End":"00:53.975","Text":"cause the heart muscles to contract and relax as they should."},{"Start":"00:53.975 ","End":"00:57.740","Text":"We have innervation of our skeletal muscle, for instance,"},{"Start":"00:57.740 ","End":"00:59.915","Text":"that allows us to move our muscles,"},{"Start":"00:59.915 ","End":"01:02.017","Text":"to contract them or relax them,"},{"Start":"01:02.017 ","End":"01:04.835","Text":"something similar happens in the heart,"},{"Start":"01:04.835 ","End":"01:12.110","Text":"but it is not regulated consciously, it\u0027s regulated subconsciously."},{"Start":"01:12.110 ","End":"01:19.205","Text":"We have 2 different kinds of movements of the heart muscle we call diastole,"},{"Start":"01:19.205 ","End":"01:21.860","Text":"which is the relaxation phase of the heart."},{"Start":"01:21.860 ","End":"01:26.089","Text":"During that period, the heart fills with blood and we have the systole,"},{"Start":"01:26.089 ","End":"01:28.610","Text":"that\u0027s the contraction, that\u0027s when the blood is pushed"},{"Start":"01:28.610 ","End":"01:32.750","Text":"out of the heart into the rest of the body."},{"Start":"01:32.750 ","End":"01:35.700","Text":"The atria, of course,"},{"Start":"01:35.750 ","End":"01:38.580","Text":"the parts on top here,"},{"Start":"01:38.580 ","End":"01:40.200","Text":"these chambers on top,"},{"Start":"01:40.200 ","End":"01:46.025","Text":"contract to move blood into the ventricles and they contract at the same time,"},{"Start":"01:46.025 ","End":"01:50.105","Text":"which forces the blood into the ventricles,"},{"Start":"01:50.105 ","End":"01:54.455","Text":"as we said, as you can see here on the left side and on the right side."},{"Start":"01:54.455 ","End":"02:02.655","Text":"There are the appropriate closing of the atrioventricular valves that keep the blood"},{"Start":"02:02.655 ","End":"02:05.640","Text":"from moving out into the aorta or into"},{"Start":"02:05.640 ","End":"02:10.880","Text":"the pulmonary artery and that sounds if you\u0027re listening to the chest."},{"Start":"02:10.880 ","End":"02:12.935","Text":"Then there\u0027s a delay,"},{"Start":"02:12.935 ","End":"02:16.760","Text":"and the ventricles contract at the same time, again,"},{"Start":"02:16.760 ","End":"02:19.400","Text":"the ventricles now contract at the same time and"},{"Start":"02:19.400 ","End":"02:22.640","Text":"that forces blood through the semi-lunar valves"},{"Start":"02:22.640 ","End":"02:28.897","Text":"into the aorta and pulmonary so they pump blood out now in this direction,"},{"Start":"02:28.897 ","End":"02:31.865","Text":"yes, and that sounds like a dup sound."},{"Start":"02:31.865 ","End":"02:35.330","Text":"There\u0027s this different sound when listened to a heart,"},{"Start":"02:35.330 ","End":"02:40.040","Text":"we hear different sounds depending on whether we\u0027re talking about"},{"Start":"02:40.040 ","End":"02:45.180","Text":"the systolic or diastolic beats."},{"Start":"02:45.180 ","End":"02:48.705","Text":"Let\u0027s look in now at the muscle."},{"Start":"02:48.705 ","End":"02:55.300","Text":"Of course, the muscle is what\u0027s pumping and there are muscle cells called"},{"Start":"02:55.300 ","End":"03:04.300","Text":"cardiomyocytes that are in the heart tissue and they are striated like skeletal muscle,"},{"Start":"03:04.300 ","End":"03:07.780","Text":"if you remember the structure of skeletal muscles."},{"Start":"03:07.780 ","End":"03:09.970","Text":"But unlike skeletal muscles,"},{"Start":"03:09.970 ","End":"03:13.310","Text":"they contract involuntarily in a same way,"},{"Start":"03:13.310 ","End":"03:15.610","Text":"much more similar to smooth muscle."},{"Start":"03:15.610 ","End":"03:19.960","Text":"Smooth muscle, remember is muscle that is for instances in our intestines."},{"Start":"03:19.960 ","End":"03:21.280","Text":"Now how does this work?"},{"Start":"03:21.280 ","End":"03:26.575","Text":"Well, they\u0027re connected via these what are called interpolated discs."},{"Start":"03:26.575 ","End":"03:31.400","Text":"You can see a micrograph of that over here that is"},{"Start":"03:31.400 ","End":"03:36.895","Text":"discs that are holding the different cells together."},{"Start":"03:36.895 ","End":"03:44.020","Text":"These discs are exclusive to cardiac muscle and they are self stimulating,"},{"Start":"03:44.020 ","End":"03:51.230","Text":"these muscles, they will contract on their own even if they are isolated."},{"Start":"03:51.230 ","End":"03:55.490","Text":"Sometimes, you can take these cells,"},{"Start":"03:55.490 ","End":"04:00.080","Text":"dissociate the cells from the heart and they will still beat even"},{"Start":"04:00.080 ","End":"04:05.465","Text":"on a Petri dish if they\u0027ve got the correct balance of nutrients and electrolytes."},{"Start":"04:05.465 ","End":"04:08.560","Text":"In a complete heart,"},{"Start":"04:08.560 ","End":"04:11.000","Text":"of course, there is an electrical system."},{"Start":"04:11.000 ","End":"04:14.300","Text":"There\u0027s a pacemaker, which is going to regulate"},{"Start":"04:14.300 ","End":"04:17.695","Text":"which part of the heart is going to beat when,"},{"Start":"04:17.695 ","End":"04:22.835","Text":"and that regulates this autonomous beating of the cardiac muscle, the muscle cells."},{"Start":"04:22.835 ","End":"04:25.325","Text":"We have the sinoatrial node,"},{"Start":"04:25.325 ","End":"04:27.590","Text":"that\u0027s what\u0027s called the pacemaker."},{"Start":"04:27.590 ","End":"04:29.405","Text":"This SA node over here,"},{"Start":"04:29.405 ","End":"04:31.880","Text":"which is found near the wall of the right atrium"},{"Start":"04:31.880 ","End":"04:35.105","Text":"and generates the impulses to begin with."},{"Start":"04:35.105 ","End":"04:39.635","Text":"That causes the 2 atria to contract in unison, as we mentioned,"},{"Start":"04:39.635 ","End":"04:43.145","Text":"the atria are going to be pushing blood from"},{"Start":"04:43.145 ","End":"04:47.743","Text":"the atria into the ventricles from which it\u0027s going to be pumped out,"},{"Start":"04:47.743 ","End":"04:49.975","Text":"so that\u0027s the first thing that happens."},{"Start":"04:49.975 ","End":"04:58.805","Text":"Then there\u0027s a delay, a very brief delay at this AV node for about a tenth of a second"},{"Start":"04:58.805 ","End":"05:03.110","Text":"before it spreads to the walls of the ventricles and that allows the atria to"},{"Start":"05:03.110 ","End":"05:08.380","Text":"empty completely before the blood goes into the ventricles."},{"Start":"05:08.380 ","End":"05:14.510","Text":"There are these bundle branches that passes signals to the heart apex to the bottom of"},{"Start":"05:14.510 ","End":"05:20.705","Text":"the heart over here that are going to cause the ventricles to contract."},{"Start":"05:20.705 ","End":"05:22.685","Text":"There are these fibers called"},{"Start":"05:22.685 ","End":"05:27.080","Text":"the Purkinje fibers that conduct the impulse from the apex of"},{"Start":"05:27.080 ","End":"05:34.174","Text":"the heart to the ventricular myocardium to the muscles of the ventricles,"},{"Start":"05:34.174 ","End":"05:38.794","Text":"and that\u0027s what\u0027s going to cause the ventricles to contract."},{"Start":"05:38.794 ","End":"05:42.049","Text":"Now, looking at this again, quickly,"},{"Start":"05:42.049 ","End":"05:49.430","Text":"we have the signal initiated in the sinoatrial valve and then it spreads to the atria,"},{"Start":"05:49.430 ","End":"05:50.750","Text":"causing them to contract."},{"Start":"05:50.750 ","End":"05:53.435","Text":"The signal is delayed at"},{"Start":"05:53.435 ","End":"05:58.010","Text":"the atrial ventricle node before it\u0027s passed on to the heart apex."},{"Start":"05:58.010 ","End":"06:00.830","Text":"The delay allows the atria to relax before"},{"Start":"06:00.830 ","End":"06:05.360","Text":"the ventricles contract so that we have first the atria and then the ventricles contract,"},{"Start":"06:05.360 ","End":"06:09.920","Text":"and then we have preparation for the next beat."},{"Start":"06:09.920 ","End":"06:15.305","Text":"Now, interestingly, these electrical impulses can be measured on the skin,"},{"Start":"06:15.305 ","End":"06:18.755","Text":"and you all know about electrocardiograms."},{"Start":"06:18.755 ","End":"06:27.020","Text":"They\u0027ll attach electrodes to people and you can get a trace of these pulses that"},{"Start":"06:27.020 ","End":"06:36.755","Text":"indicate the different parts of the cycle of the electrical impulses in the heart."},{"Start":"06:36.755 ","End":"06:38.225","Text":"By looking at these,"},{"Start":"06:38.225 ","End":"06:41.690","Text":"you can tell whether the heart\u0027s electrical system is working"},{"Start":"06:41.690 ","End":"06:46.590","Text":"properly or improperly on an electrocardiogram."}],"ID":30642},{"Watched":false,"Name":"Arteries and Veins","Duration":"6m 35s","ChapterTopicVideoID":29061,"CourseChapterTopicPlaylistID":294421,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.070","Text":"Let\u0027s look what happens to the blood after it leaves the heart."},{"Start":"00:04.070 ","End":"00:06.360","Text":"We\u0027ve been talking about the mammalian heart."},{"Start":"00:06.360 ","End":"00:09.060","Text":"Let\u0027s look at the blood vessels,"},{"Start":"00:09.060 ","End":"00:11.855","Text":"the arteries, and the veins."},{"Start":"00:11.855 ","End":"00:16.875","Text":"The arteries are the blood vessels that take blood away from the heart."},{"Start":"00:16.875 ","End":"00:20.625","Text":"It all starts with the aorta."},{"Start":"00:20.625 ","End":"00:24.955","Text":"The aorta is very large blood vessel that comes out of the left ventricle,"},{"Start":"00:24.955 ","End":"00:30.285","Text":"and it then branches into 2 major arteries that take blood to the different organs."},{"Start":"00:30.285 ","End":"00:36.920","Text":"Those are the carotid artery that takes"},{"Start":"00:36.920 ","End":"00:45.010","Text":"blood up to the brain and the bronchial arteries that take blood to the arms."},{"Start":"00:45.820 ","End":"00:47.855","Text":"In addition to that,"},{"Start":"00:47.855 ","End":"00:54.650","Text":"there\u0027s this thoracic artery that takes blood to the thorax and then into various organs."},{"Start":"00:54.650 ","End":"00:57.070","Text":"The hepatic, renal, gastric arteries,"},{"Start":"00:57.070 ","End":"01:00.170","Text":"these are these various arteries over here they\u0027re taking blood"},{"Start":"01:00.170 ","End":"01:03.745","Text":"to the liver, kidneys, stomach respectively."},{"Start":"01:03.745 ","End":"01:05.750","Text":"Then finally, we have"},{"Start":"01:05.750 ","End":"01:12.200","Text":"the iliac artery that is taking blood down into our lower extremities."},{"Start":"01:12.200 ","End":"01:16.504","Text":"The major arteries diverge into these minor arteries"},{"Start":"01:16.504 ","End":"01:21.394","Text":"because they branch and branch and branch and then smaller,"},{"Start":"01:21.394 ","End":"01:22.620","Text":"what are called arterioles,"},{"Start":"01:22.620 ","End":"01:23.930","Text":"once they become even smaller,"},{"Start":"01:23.930 ","End":"01:28.680","Text":"we call them not artery."},{"Start":"01:28.680 ","End":"01:32.809","Text":"Here the arteries and arterioles."},{"Start":"01:32.809 ","End":"01:37.940","Text":"Finally, they continue to branch until they are extremely narrow,"},{"Start":"01:37.940 ","End":"01:44.360","Text":"so narrow that only 1 red blood vessel can get through at a time,"},{"Start":"01:44.360 ","End":"01:47.795","Text":"and they become what are called capillaries."},{"Start":"01:47.795 ","End":"01:50.990","Text":"There are 5-10 microns in diameter,"},{"Start":"01:50.990 ","End":"01:56.870","Text":"and the red blood cells can travel through only in a single file."},{"Start":"01:56.870 ","End":"02:02.044","Text":"Of course it\u0027s in the capillaries is where we have the nutrients,"},{"Start":"02:02.044 ","End":"02:05.270","Text":"waste, and oxygen exchange at the cellular level."},{"Start":"02:05.270 ","End":"02:09.050","Text":"There is fluid which can also diffuse through"},{"Start":"02:09.050 ","End":"02:13.235","Text":"these capillaries into the interstitial space from these capillaries,"},{"Start":"02:13.235 ","End":"02:15.140","Text":"eventually through the lymph system,"},{"Start":"02:15.140 ","End":"02:18.590","Text":"this liquid will find its way back to the heart."},{"Start":"02:18.590 ","End":"02:25.675","Text":"The capillaries again continue and they become venules."},{"Start":"02:25.675 ","End":"02:29.005","Text":"The branching is goes in the other direction as well,"},{"Start":"02:29.005 ","End":"02:36.955","Text":"until eventually we have these veins that take the deoxygenated blood back to the heart."},{"Start":"02:36.955 ","End":"02:38.555","Text":"Let\u0027s look at the veins."},{"Start":"02:38.555 ","End":"02:41.960","Text":"The veins are these blood vessels that bring blood back to the heart,"},{"Start":"02:41.960 ","End":"02:44.895","Text":"except actually there\u0027s 1 vein,"},{"Start":"02:44.895 ","End":"02:51.830","Text":"the pulmonary vein, which is coming from the lungs back to the heart."},{"Start":"02:51.830 ","End":"02:55.075","Text":"Of course that is oxygenated."},{"Start":"02:55.075 ","End":"03:01.100","Text":"The major veins drain blood from the organs and limbs and of course,"},{"Start":"03:01.100 ","End":"03:04.495","Text":"that is primarily deoxygenated blood."},{"Start":"03:04.495 ","End":"03:09.605","Text":"The veins are thinner walled than the arteries,"},{"Start":"03:09.605 ","End":"03:17.075","Text":"because of course the pressure is going to be lower in the veins and the arteries,"},{"Start":"03:17.075 ","End":"03:22.470","Text":"the heart is going to be creating the pressure in the arteries."},{"Start":"03:22.470 ","End":"03:24.785","Text":"Some of the fluid, as we said,"},{"Start":"03:24.785 ","End":"03:29.150","Text":"comes back to the heart via the lymphatic system."},{"Start":"03:29.150 ","End":"03:33.604","Text":"Let\u0027s have a look at what the arteries"},{"Start":"03:33.604 ","End":"03:38.680","Text":"and the veins are made of or what the layers are just like we did for the heart."},{"Start":"03:38.680 ","End":"03:43.144","Text":"There\u0027s the innermost, what\u0027s called tunica intima,"},{"Start":"03:43.144 ","End":"03:45.770","Text":"the inside of each of them,"},{"Start":"03:45.770 ","End":"03:48.930","Text":"this is what comes in contact with the blood and capillaries"},{"Start":"03:48.930 ","End":"03:52.520","Text":"this layer is where the diffusion occurs of the oxygen,"},{"Start":"03:52.520 ","End":"03:55.060","Text":"carbon dioxide, and other materials."},{"Start":"03:55.060 ","End":"03:59.990","Text":"Then we have middle layer, this tunica media."},{"Start":"03:59.990 ","End":"04:05.525","Text":"It\u0027s a smooth muscle that regulates the blood flow by contracting"},{"Start":"04:05.525 ","End":"04:11.470","Text":"or dilating and that makes these tissues either tighter or less tighter,"},{"Start":"04:11.470 ","End":"04:16.130","Text":"that\u0027s called vasoconstriction or vasodilation."},{"Start":"04:16.130 ","End":"04:21.620","Text":"Then on the outside there\u0027s an additional layer,"},{"Start":"04:21.620 ","End":"04:25.610","Text":"which is connective tissue similar to what we have on the outside of the heart"},{"Start":"04:25.610 ","End":"04:30.065","Text":"that supports the structure of the vessel altogether."},{"Start":"04:30.065 ","End":"04:32.990","Text":"The arteries are thicker,"},{"Start":"04:32.990 ","End":"04:35.405","Text":"they have to deal with higher pressure"},{"Start":"04:35.405 ","End":"04:39.260","Text":"and so there\u0027s a higher pressure of the heart and they"},{"Start":"04:39.260 ","End":"04:46.790","Text":"also can speed the freshly pump blood by constricting themselves."},{"Start":"04:46.790 ","End":"04:49.190","Text":"The veins, on the other hand,"},{"Start":"04:49.190 ","End":"04:57.200","Text":"are thinner and we see that they have valves in them that are"},{"Start":"04:57.200 ","End":"05:06.450","Text":"one-way valves similar to what we had in the heart and each valve contains 2 flaps."},{"Start":"05:07.100 ","End":"05:09.335","Text":"The edges of these meat,"},{"Start":"05:09.335 ","End":"05:13.534","Text":"which allows the blood flow to go only in 1 direction,"},{"Start":"05:13.534 ","End":"05:15.440","Text":"not in both directions."},{"Start":"05:15.440 ","End":"05:19.220","Text":"The blood is moving towards the heart and that keeps"},{"Start":"05:19.220 ","End":"05:23.405","Text":"the cusps open if the blood tries to go in the opposite direction,"},{"Start":"05:23.405 ","End":"05:24.755","Text":"like down the leg,"},{"Start":"05:24.755 ","End":"05:28.280","Text":"for instance, then the valve keeps that from happening."},{"Start":"05:28.280 ","End":"05:34.655","Text":"In addition to that around the veins,"},{"Start":"05:34.655 ","End":"05:37.215","Text":"they\u0027re also skeletal muscles."},{"Start":"05:37.215 ","End":"05:38.760","Text":"Let\u0027s say in our legs for instance."},{"Start":"05:38.760 ","End":"05:42.515","Text":"When we move and those muscles contract,"},{"Start":"05:42.515 ","End":"05:47.225","Text":"they help force the blood back in the other direction or in the direction"},{"Start":"05:47.225 ","End":"05:51.965","Text":"of the heart and that helps move our circulation as well."},{"Start":"05:51.965 ","End":"05:56.195","Text":"Therefore, people, for instance who are wheelchair bound have"},{"Start":"05:56.195 ","End":"06:01.140","Text":"circulatory problems because they\u0027re not moving these muscles."},{"Start":"06:01.140 ","End":"06:06.920","Text":"They need some physical therapy in order to keep the blood moving as it should."},{"Start":"06:06.920 ","End":"06:10.610","Text":"The older people as well should keep moving as much as they"},{"Start":"06:10.610 ","End":"06:14.615","Text":"possibly can to help their circulation keep going."},{"Start":"06:14.615 ","End":"06:17.750","Text":"The veins that are embedded in the muscle or are compressed during"},{"Start":"06:17.750 ","End":"06:20.570","Text":"the constriction that muscle and causes an increase in"},{"Start":"06:20.570 ","End":"06:24.700","Text":"blood pressure inside these veins and"},{"Start":"06:24.700 ","End":"06:34.230","Text":"the one-way valves keep the blood moving always in the same direction towards the heart."}],"ID":30643}],"Thumbnail":null,"ID":294421},{"Name":"Blood Flow and Blood Pressure Regulation","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Blood Flow and Pressure as it Moves Through the Cappilaries and Veins","Duration":"7m 45s","ChapterTopicVideoID":29055,"CourseChapterTopicPlaylistID":294422,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.050 ","End":"00:07.710","Text":"Hi there. I\u0027m glad you\u0027re back to continue our discussion of the circulatory system."},{"Start":"00:07.710 ","End":"00:13.200","Text":"We\u0027ve discussed until now the composition of the blood and how it does"},{"Start":"00:13.200 ","End":"00:16.590","Text":"gas exchange and moves things around and we\u0027ve"},{"Start":"00:16.590 ","End":"00:20.550","Text":"discussed the structure of the circulatory system,"},{"Start":"00:20.550 ","End":"00:25.365","Text":"but we haven\u0027t spoken so much about how the blood flows."},{"Start":"00:25.365 ","End":"00:30.075","Text":"In this section we\u0027re going to be discussing blood flow and"},{"Start":"00:30.075 ","End":"00:35.530","Text":"the blood pressure regulation that will help move that blood around."},{"Start":"00:35.530 ","End":"00:39.285","Text":"Our blood pressure that we\u0027re all familiar with is the pressure that\u0027s"},{"Start":"00:39.285 ","End":"00:43.340","Text":"exerted by the blood on the walls of the blood vessels."},{"Start":"00:43.340 ","End":"00:47.645","Text":"Of course, that pressure is going to be dependent on how"},{"Start":"00:47.645 ","End":"00:54.810","Text":"fast the blood is moving and how hard our heart is beating."},{"Start":"00:55.460 ","End":"01:02.450","Text":"There are many factors that can affect blood pressure in addition to how"},{"Start":"01:02.450 ","End":"01:05.060","Text":"fast the blood is moving and there are"},{"Start":"01:05.060 ","End":"01:08.585","Text":"various things that will control that such as hormones,"},{"Start":"01:08.585 ","End":"01:11.165","Text":"stress, exercise of course."},{"Start":"01:11.165 ","End":"01:13.235","Text":"Whether we\u0027re eating or not,"},{"Start":"01:13.235 ","End":"01:16.160","Text":"whether we\u0027re sitting, whether we\u0027re standing and so on."},{"Start":"01:16.160 ","End":"01:20.180","Text":"The blood flow through the body is regulated at the end of the day by"},{"Start":"01:20.180 ","End":"01:25.099","Text":"the size of the blood vessels and the action of the muscle,"},{"Start":"01:25.099 ","End":"01:28.325","Text":"the smooth muscle that is helping move"},{"Start":"01:28.325 ","End":"01:31.985","Text":"the blood through those vessels as we saw in the previous section,"},{"Start":"01:31.985 ","End":"01:34.730","Text":"the one-way valves that keep the blood from moving"},{"Start":"01:34.730 ","End":"01:40.580","Text":"backwards and the pressure of the fluid in the blood itself,"},{"Start":"01:40.580 ","End":"01:45.005","Text":"the fluid pressure of the blood."},{"Start":"01:45.005 ","End":"01:50.545","Text":"Let\u0027s look at how the blood flows through the arteries."},{"Start":"01:50.545 ","End":"01:57.035","Text":"Of course, our heart is pushing blood through our arteries and with each heart pump,"},{"Start":"01:57.035 ","End":"02:03.670","Text":"blood is pushed into the aorta under very high pressure and velocity."},{"Start":"02:03.670 ","End":"02:10.115","Text":"As the heart begins to pump and blood pushes through the aorta,"},{"Start":"02:10.115 ","End":"02:12.275","Text":"we have a high velocity,"},{"Start":"02:12.275 ","End":"02:15.275","Text":"as we can see in the aorta,"},{"Start":"02:15.275 ","End":"02:20.330","Text":"as the blood then goes to the arteries and the arterioles and the capillaries,"},{"Start":"02:20.330 ","End":"02:24.515","Text":"the velocity is going to go down because"},{"Start":"02:24.515 ","End":"02:31.805","Text":"the total number of blood vessels is going to increase,"},{"Start":"02:31.805 ","End":"02:37.355","Text":"so the total area increases the vascular bed,"},{"Start":"02:37.355 ","End":"02:41.930","Text":"whereas the velocity in each of these decreases."},{"Start":"02:41.930 ","End":"02:47.330","Text":"In the aorta, the blood travels at the speed of about 40 centimeters per second."},{"Start":"02:47.330 ","End":"02:48.650","Text":"That\u0027s really fast."},{"Start":"02:48.650 ","End":"02:52.105","Text":"But as the blood moves into the arteries,"},{"Start":"02:52.105 ","End":"02:55.610","Text":"we can see here the arterioles, the capillary beds,"},{"Start":"02:55.610 ","End":"03:03.465","Text":"the rate moves down very low to about 0.026 centimeters per second."},{"Start":"03:03.465 ","End":"03:05.250","Text":"That\u0027s really slow,"},{"Start":"03:05.250 ","End":"03:11.210","Text":"and that\u0027s due to the overall diameter of these combined blood vessels,"},{"Start":"03:11.210 ","End":"03:13.105","Text":"as we mentioned earlier."},{"Start":"03:13.105 ","End":"03:17.315","Text":"The slow rate of travel through the capillary beds assists"},{"Start":"03:17.315 ","End":"03:21.740","Text":"with gas exchange because as the blood is moving through the capillaries,"},{"Start":"03:21.740 ","End":"03:24.800","Text":"it needs to be moving slowly so that there can be"},{"Start":"03:24.800 ","End":"03:30.200","Text":"an efficient gas exchange and nutrient exchange and that then promotes"},{"Start":"03:30.200 ","End":"03:35.150","Text":"diffusion in and out of the blood into"},{"Start":"03:35.150 ","End":"03:41.060","Text":"the systemic area and in the lungs for that matter as well."},{"Start":"03:41.060 ","End":"03:43.189","Text":"Let\u0027s look at the veins."},{"Start":"03:43.189 ","End":"03:46.540","Text":"In the veins, we have an opposite situation."},{"Start":"03:46.540 ","End":"03:52.975","Text":"After the blood has passed through the capillaries and into the venules,"},{"Start":"03:52.975 ","End":"03:55.605","Text":"and then into the veins,"},{"Start":"03:55.605 ","End":"03:59.750","Text":"we can see that the flow rate increases of course,"},{"Start":"03:59.750 ","End":"04:03.665","Text":"because there\u0027s going to be fewer blood vessels,"},{"Start":"04:03.665 ","End":"04:09.920","Text":"but at a much slower rate than in the aorta, of course."},{"Start":"04:09.920 ","End":"04:13.940","Text":"We can see that the total area of course in"},{"Start":"04:13.940 ","End":"04:19.010","Text":"the capillaries as high as we mentioned before,"},{"Start":"04:19.010 ","End":"04:20.930","Text":"total area goes down,"},{"Start":"04:20.930 ","End":"04:25.220","Text":"but the rate won\u0027t reach what it was in the aorta."},{"Start":"04:25.220 ","End":"04:28.085","Text":"Blood primarily moves to the veins, as we know,"},{"Start":"04:28.085 ","End":"04:31.010","Text":"by the rhythmic movement of the smooth muscle that\u0027s in"},{"Start":"04:31.010 ","End":"04:35.480","Text":"those veins as well as a skeletal muscle pushing the blood"},{"Start":"04:35.480 ","End":"04:39.530","Text":"along and the one-way valves ensure that there is"},{"Start":"04:39.530 ","End":"04:44.125","Text":"not a regression of blood in the wrong direction,"},{"Start":"04:44.125 ","End":"04:48.120","Text":"so from here, from right to left through the veins."},{"Start":"04:48.120 ","End":"04:53.135","Text":"The skeletal muscle contraction aids this and we have"},{"Start":"04:53.135 ","End":"04:58.594","Text":"a lower blood flow than we did in the aorta initially."},{"Start":"04:58.594 ","End":"05:00.485","Text":"In addition to that,"},{"Start":"05:00.485 ","End":"05:05.900","Text":"blood flow is regulated both in the veins and in the arteries by"},{"Start":"05:05.900 ","End":"05:11.960","Text":"the diameter of the blood vessels,"},{"Start":"05:11.960 ","End":"05:17.284","Text":"and so we can have vasodilation where the blood vessels get larger."},{"Start":"05:17.284 ","End":"05:21.695","Text":"They can get smaller via vasoconstriction,"},{"Start":"05:21.695 ","End":"05:24.350","Text":"and we can have something in the middle."},{"Start":"05:24.350 ","End":"05:30.220","Text":"Those things are going to be directed either by nerves or hormones."},{"Start":"05:30.220 ","End":"05:32.330","Text":"For example, after a large meal,"},{"Start":"05:32.330 ","End":"05:37.995","Text":"most of the blood is diverted to the stomach by vasodilation."},{"Start":"05:37.995 ","End":"05:47.345","Text":"The digestive system then needs to get most of the blood so that it can act efficiently."},{"Start":"05:47.345 ","End":"05:50.405","Text":"However, during exercise, we have the opposite."},{"Start":"05:50.405 ","End":"05:53.390","Text":"Blood is diverted to the skeletal muscles"},{"Start":"05:53.390 ","End":"05:56.855","Text":"because they\u0027re the ones that need the energy via"},{"Start":"05:56.855 ","End":"06:05.275","Text":"vasodilation while the blood to the digestive system is lessened via vasoconstriction."},{"Start":"06:05.275 ","End":"06:08.795","Text":"We can often see that the people exercising,"},{"Start":"06:08.795 ","End":"06:13.520","Text":"we can see that there are blood vessels are much larger."},{"Start":"06:13.520 ","End":"06:21.050","Text":"They may even be seen through the muscle in the outside of people who are exercising,"},{"Start":"06:21.050 ","End":"06:22.955","Text":"whereas people who are sitting at rest,"},{"Start":"06:22.955 ","End":"06:26.710","Text":"those blood vessels are less visible."},{"Start":"06:26.710 ","End":"06:28.545","Text":"How does that work?"},{"Start":"06:28.545 ","End":"06:32.960","Text":"Part of the way that that works is that they\u0027re actually these sphincters."},{"Start":"06:32.960 ","End":"06:38.330","Text":"They\u0027re these little valves that are in the precapillary areas that"},{"Start":"06:38.330 ","End":"06:44.285","Text":"will either allow blood flow through or not allow it through,"},{"Start":"06:44.285 ","End":"06:49.430","Text":"depending on how much blood the particular tissue needs."},{"Start":"06:49.430 ","End":"06:51.080","Text":"If the sphincters are open,"},{"Start":"06:51.080 ","End":"06:54.275","Text":"as I said, then the blood will flow through."},{"Start":"06:54.275 ","End":"06:56.420","Text":"But what if it\u0027s not, if they\u0027re closed?"},{"Start":"06:56.420 ","End":"06:59.360","Text":"If they\u0027re closed and blood is not going through still,"},{"Start":"06:59.360 ","End":"07:01.390","Text":"the blood needs to travel to the veins,"},{"Start":"07:01.390 ","End":"07:06.740","Text":"so it turns out that there is something called the thoroughfare channel."},{"Start":"07:06.740 ","End":"07:10.205","Text":"This channel in the middle here, this thoroughfare channel,"},{"Start":"07:10.205 ","End":"07:13.640","Text":"which does not have these sphincters and then the blood can"},{"Start":"07:13.640 ","End":"07:17.820","Text":"flow through from the artery to the vein."},{"Start":"07:17.820 ","End":"07:21.560","Text":"This allows very precise control about when"},{"Start":"07:21.560 ","End":"07:26.075","Text":"the capillary beds receive the blood and when they don\u0027t,"},{"Start":"07:26.075 ","End":"07:29.570","Text":"according to the needs of the tissue that\u0027s there."},{"Start":"07:29.570 ","End":"07:31.815","Text":"At any given moment,"},{"Start":"07:31.815 ","End":"07:35.145","Text":"it turns out that only between 5 and 10 percent"},{"Start":"07:35.145 ","End":"07:38.420","Text":"of the capillary beds have blood flowing through them,"},{"Start":"07:38.420 ","End":"07:44.940","Text":"so most of the time there is not blood flowing through them."}],"ID":30660},{"Watched":false,"Name":"Water Movement in and out of the Cappilaries and Lymph System","Duration":"4m 14s","ChapterTopicVideoID":29057,"CourseChapterTopicPlaylistID":294422,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.770","Text":"Welcome back."},{"Start":"00:01.770 ","End":"00:10.215","Text":"We\u0027ve been discussing blood flow and blood pressure regulation in the previous video."},{"Start":"00:10.215 ","End":"00:15.675","Text":"We\u0027ve been talking about blood going through blood vessels."},{"Start":"00:15.675 ","End":"00:21.285","Text":"We have not been talking about blood or components of blood leaving"},{"Start":"00:21.285 ","End":"00:27.194","Text":"or coming back into the blood vessels by diffusion."},{"Start":"00:27.194 ","End":"00:30.000","Text":"Of course, that\u0027s really what it\u0027s all about."},{"Start":"00:30.000 ","End":"00:32.355","Text":"It\u0027s about delivering oxygen,"},{"Start":"00:32.355 ","End":"00:34.515","Text":"about taking carbon dioxide away,"},{"Start":"00:34.515 ","End":"00:37.935","Text":"delivering nutrients, and taking waste products away."},{"Start":"00:37.935 ","End":"00:40.290","Text":"Well, water, as it turns out,"},{"Start":"00:40.290 ","End":"00:43.680","Text":"also can move through"},{"Start":"00:43.680 ","End":"00:48.380","Text":"the sides of the capillaries and let\u0027s think about that for a moment."},{"Start":"00:48.380 ","End":"00:54.245","Text":"Of course, large molecules like proteins can\u0027t leave the capillaries."},{"Start":"00:54.245 ","End":"00:58.490","Text":"However, water can, and there is a loss of"},{"Start":"00:58.490 ","End":"01:05.885","Text":"watery plasma that creates a hyperosmotic solution within the capillaries."},{"Start":"01:05.885 ","End":"01:11.735","Text":"What does that mean? That means that if the partial pressure"},{"Start":"01:11.735 ","End":"01:17.270","Text":"of the water inside the capillaries is greater than it is on the outside,"},{"Start":"01:17.270 ","End":"01:21.905","Text":"we\u0027ll have some sort of a filtration and that"},{"Start":"01:21.905 ","End":"01:25.895","Text":"the hydrostatic pressure is"},{"Start":"01:25.895 ","End":"01:33.365","Text":"about 25 millimeters of mercury on the inside of the capillary."},{"Start":"01:33.365 ","End":"01:37.340","Text":"So if it\u0027s larger inside than outside,"},{"Start":"01:37.340 ","End":"01:39.260","Text":"we\u0027ll have water moving out."},{"Start":"01:39.260 ","End":"01:43.880","Text":"If it\u0027s larger on the outside than it is on the inside,"},{"Start":"01:43.880 ","End":"01:47.720","Text":"then we\u0027re going to have movement of water back into"},{"Start":"01:47.720 ","End":"01:52.440","Text":"the capillaries through a process of reabsorption."},{"Start":"01:52.440 ","End":"01:57.770","Text":"Actually, this causes about 85 percent of the plasma that leaves"},{"Start":"01:57.770 ","End":"02:02.570","Text":"the capillaries to diffuse back into the capillaries."},{"Start":"02:02.570 ","End":"02:05.930","Text":"So there\u0027s this movement back and forth and"},{"Start":"02:05.930 ","End":"02:10.115","Text":"the remaining 15 percent of the blood plasma actually stays out."},{"Start":"02:10.115 ","End":"02:16.190","Text":"It drains out from the interstitial fluid into the nearby lymphatic vessels."},{"Start":"02:16.190 ","End":"02:18.619","Text":"Now, what are lymphatic vessels?"},{"Start":"02:18.619 ","End":"02:23.405","Text":"It turns out that in addition to the capillaries in the blood that\u0027s traveling through,"},{"Start":"02:23.405 ","End":"02:29.160","Text":"there\u0027s another system called the lymph system."},{"Start":"02:30.110 ","End":"02:35.260","Text":"In this, there\u0027s this interstitial fluid which"},{"Start":"02:35.260 ","End":"02:39.890","Text":"is similar in composition in the lymph to what\u0027s on the outside."},{"Start":"02:39.890 ","End":"02:49.800","Text":"So we have movement of materials from the interstitial fluid into the lymph system."},{"Start":"02:49.800 ","End":"02:56.785","Text":"That lymph system then moves back eventually to the heart, as we\u0027ll see."},{"Start":"02:56.785 ","End":"03:03.050","Text":"It passes through these lymph nodes before it returns to the heart via the vena cava."},{"Start":"03:03.050 ","End":"03:07.430","Text":"And there these lymph nodes that are in various places there areas in which"},{"Start":"03:07.430 ","End":"03:16.520","Text":"the various lymph vessels are moving lymph into the direction of the center,"},{"Start":"03:16.520 ","End":"03:18.050","Text":"so these lymph nodes,"},{"Start":"03:18.050 ","End":"03:25.280","Text":"and then through lymphatic vessel which eventually ends up at the heart in the vena cava."},{"Start":"03:25.280 ","End":"03:27.650","Text":"There are white blood cells that remove"},{"Start":"03:27.650 ","End":"03:31.640","Text":"infectious agents that clean this lymph before returns to the bloodstream."},{"Start":"03:31.640 ","End":"03:36.790","Text":"Actually, this lymph system is also part of the immune system."},{"Start":"03:36.790 ","End":"03:39.560","Text":"After the lymph is cleared,"},{"Start":"03:39.560 ","End":"03:43.955","Text":"it returns to the heart and it\u0027s moved by the action of smooth muscle"},{"Start":"03:43.955 ","End":"03:48.830","Text":"pumping of the lymph system and there\u0027s also skeletal muscle action,"},{"Start":"03:48.830 ","End":"03:52.505","Text":"of course, that\u0027s moving things and there are also"},{"Start":"03:52.505 ","End":"03:58.880","Text":"one-way valves that prevent the lymph moving back in the opposite direction."},{"Start":"03:58.880 ","End":"04:01.400","Text":"Just like in the veins,"},{"Start":"04:01.400 ","End":"04:03.655","Text":"the blood can only move in one direction."},{"Start":"04:03.655 ","End":"04:07.550","Text":"The lymph fluid then returns to the blood near"},{"Start":"04:07.550 ","End":"04:13.290","Text":"the junction of the vena cava and enters the right atrium of the heart."}],"ID":30661},{"Watched":false,"Name":"Blood Pressure","Duration":"4m 51s","ChapterTopicVideoID":29056,"CourseChapterTopicPlaylistID":294422,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.710","Text":"In the previous video,"},{"Start":"00:01.710 ","End":"00:06.765","Text":"we discussed the blood pressure inside the capillaries,"},{"Start":"00:06.765 ","End":"00:11.835","Text":"this hydrostatic pressure which is inside the capillaries."},{"Start":"00:11.835 ","End":"00:15.510","Text":"Of course, it\u0027s the pressure of the blood against the walls"},{"Start":"00:15.510 ","End":"00:19.215","Text":"of the blood vessels which is causing this blood pressure."},{"Start":"00:19.215 ","End":"00:27.240","Text":"Now we all know that our blood pressure can be taken by putting a cuff around our arm,"},{"Start":"00:27.240 ","End":"00:30.005","Text":"and then it measures 2 different numbers."},{"Start":"00:30.005 ","End":"00:37.665","Text":"There\u0027s a systolic and diastolic number that is expressed, what does that mean?"},{"Start":"00:37.665 ","End":"00:40.985","Text":"Well, turns out that in the arteries,"},{"Start":"00:40.985 ","End":"00:43.565","Text":"the hydrostatic pressure near the heart,"},{"Start":"00:43.565 ","End":"00:45.215","Text":"of course, is very high."},{"Start":"00:45.215 ","End":"00:48.919","Text":"We\u0027ve seen that before, and then the blood as it flows to the arterioles,"},{"Start":"00:48.919 ","End":"00:51.300","Text":"the rate of flow is going to be slow,"},{"Start":"00:51.300 ","End":"00:54.290","Text":"that we know, and the pressure goes down."},{"Start":"00:54.290 ","End":"00:56.480","Text":"But during the systole,"},{"Start":"00:56.480 ","End":"01:02.365","Text":"the artery walls stretch to accommodate this increase of pressure and extra blood."},{"Start":"01:02.365 ","End":"01:04.380","Text":"Then during the diastole,"},{"Start":"01:04.380 ","End":"01:12.694","Text":"when the heart is allowing the blood to go from the atria into the ventricles,"},{"Start":"01:12.694 ","End":"01:17.835","Text":"then the walls return to their normal size because of elastic properties."},{"Start":"01:17.835 ","End":"01:21.785","Text":"These pressures change and they can be read"},{"Start":"01:21.785 ","End":"01:28.565","Text":"by the pressure readings that are taken during blood pressure measurements."},{"Start":"01:28.565 ","End":"01:32.990","Text":"We\u0027ll see sometimes or we\u0027ll often see two numbers,"},{"Start":"01:32.990 ","End":"01:38.490","Text":"we\u0027ll see the systole over diastole numbers."},{"Start":"01:38.490 ","End":"01:40.715","Text":"We\u0027ll say 120 over 80,"},{"Start":"01:40.715 ","End":"01:46.910","Text":"those are the different pressures that are measured in millimeters of mercury."},{"Start":"01:46.910 ","End":"01:51.545","Text":"Now, the blood pressure is also regulated, of course,"},{"Start":"01:51.545 ","End":"01:56.405","Text":"by the resistance of the peripheral regions."},{"Start":"01:56.405 ","End":"02:02.855","Text":"As the blood has to go through narrower and narrower blood vessels,"},{"Start":"02:02.855 ","End":"02:04.085","Text":"the resistance, of course,"},{"Start":"02:04.085 ","End":"02:06.535","Text":"is going to increase."},{"Start":"02:06.535 ","End":"02:11.645","Text":"That also is controlled by the constriction of the arteries."},{"Start":"02:11.645 ","End":"02:17.650","Text":"As we know, the arteries have this muscular structure,"},{"Start":"02:17.650 ","End":"02:21.000","Text":"then the muscles can contract."},{"Start":"02:21.000 ","End":"02:24.290","Text":"As we have constriction,"},{"Start":"02:24.290 ","End":"02:25.955","Text":"the resistance increases,"},{"Start":"02:25.955 ","End":"02:30.050","Text":"but when they dilate the resistance decreases."},{"Start":"02:30.050 ","End":"02:32.000","Text":"Throughout the cardiac cycle,"},{"Start":"02:32.000 ","End":"02:35.990","Text":"the blood continues to empty into the arterioles at"},{"Start":"02:35.990 ","End":"02:44.365","Text":"a relatively even rate because the peripheral resistance is regulated."},{"Start":"02:44.365 ","End":"02:47.565","Text":"There\u0027s this blood pressure regulation,"},{"Start":"02:47.565 ","End":"02:50.585","Text":"and, of course, the cardiac in the cardiac output,"},{"Start":"02:50.585 ","End":"02:56.780","Text":"how much blood is coming out of the heart is controlled by two different things."},{"Start":"02:56.780 ","End":"02:58.400","Text":"By the heart rate,"},{"Start":"02:58.400 ","End":"03:01.685","Text":"that is how fast the heart is beating,"},{"Start":"03:01.685 ","End":"03:03.055","Text":"beats per minute,"},{"Start":"03:03.055 ","End":"03:06.410","Text":"and what the volume is of each beat,"},{"Start":"03:06.410 ","End":"03:09.710","Text":"we\u0027ll call that the stroke volume."},{"Start":"03:09.710 ","End":"03:13.580","Text":"The cardiac output can be increased by"},{"Start":"03:13.580 ","End":"03:19.030","Text":"increasing either or both the heart rate and the stroke volume."},{"Start":"03:19.030 ","End":"03:24.560","Text":"The stroke volume can be increased by speeding blood circulation through"},{"Start":"03:24.560 ","End":"03:30.670","Text":"the body so that more blood then enters the heart between constrictions."},{"Start":"03:30.670 ","End":"03:33.095","Text":"It\u0027s not only what\u0027s happening in the heart,"},{"Start":"03:33.095 ","End":"03:35.360","Text":"it\u0027s also what\u0027s happening in"},{"Start":"03:35.360 ","End":"03:41.780","Text":"the circulatory system as to how much blood is going to get back to the heart."},{"Start":"03:41.780 ","End":"03:44.150","Text":"The blood pressure regulation then,"},{"Start":"03:44.150 ","End":"03:47.630","Text":"is affected by many different factors."},{"Start":"03:47.630 ","End":"03:52.630","Text":"Yes, those that affect the heart rate and those that affect the stroke volume."},{"Start":"03:52.630 ","End":"03:55.730","Text":"You can see that there are considerable number of"},{"Start":"03:55.730 ","End":"03:59.285","Text":"things which can affect both of these things."},{"Start":"03:59.285 ","End":"04:01.730","Text":"Now, during heavy exertion, for instance,"},{"Start":"04:01.730 ","End":"04:03.200","Text":"the blood vessels will relax,"},{"Start":"04:03.200 ","End":"04:04.565","Text":"as we\u0027ve mentioned earlier."},{"Start":"04:04.565 ","End":"04:08.930","Text":"They increase in diameter and that offsets the increased heart rate"},{"Start":"04:08.930 ","End":"04:13.475","Text":"that ensures adequate oxygenation of the muscles."},{"Start":"04:13.475 ","End":"04:16.620","Text":"During stress, the opposite happens,"},{"Start":"04:16.620 ","End":"04:19.260","Text":"blood vessels decrease in diameter,"},{"Start":"04:19.260 ","End":"04:21.810","Text":"and that increases blood pressure."},{"Start":"04:21.810 ","End":"04:24.440","Text":"That allows more blood, for instance,"},{"Start":"04:24.440 ","End":"04:27.785","Text":"to get to the brain so we can think more carefully."},{"Start":"04:27.785 ","End":"04:31.025","Text":"These changes can also be caused by"},{"Start":"04:31.025 ","End":"04:35.375","Text":"nerve signals like we might get during stress or hormones,"},{"Start":"04:35.375 ","End":"04:40.640","Text":"and they can also even change when we stand up or lie down."},{"Start":"04:40.640 ","End":"04:43.280","Text":"We know that when we have our blood pressure taken,"},{"Start":"04:43.280 ","End":"04:46.790","Text":"they ask us to relax and sometimes even lie"},{"Start":"04:46.790 ","End":"04:51.540","Text":"down because that can affect the blood pressure reading."}],"ID":30662}],"Thumbnail":null,"ID":294422},{"Name":"Exercises","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Exercise 1","Duration":"1m 23s","ChapterTopicVideoID":29072,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":"https://www.proprep.uk/Images/Videos_Thumbnails/29072.jpeg","UploadDate":"2022-06-01T07:04:32.9670000","DurationForVideoObject":"PT1M23S","Description":null,"MetaTitle":"Exercise 1 - Exercises: Practice Makes Perfect | Proprep","MetaDescription":"Studied the topic name and want to practice? Here are some exercises on Exercises practice questions for you to maximize your understanding.","Canonical":"https://www.proprep.uk/general-modules/all/introduction-to-biology/the-circulatory-system/exercises/vid30912","VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.805","Text":"Why are open circulatory systems advantageous to some animals?"},{"Start":"00:05.805 ","End":"00:09.675","Text":"Is it because they use less metabolic energy,"},{"Start":"00:09.675 ","End":"00:12.795","Text":"because they help the animal move faster,"},{"Start":"00:12.795 ","End":"00:15.435","Text":"because they do not need a heart,"},{"Start":"00:15.435 ","End":"00:19.746","Text":"or because they help large insects develop?"},{"Start":"00:19.746 ","End":"00:21.960","Text":"An open circulatory system,"},{"Start":"00:21.960 ","End":"00:29.835","Text":"remember that\u0027s one that does not return the blood to the heart directly through veins,"},{"Start":"00:29.835 ","End":"00:35.205","Text":"but rather it goes through the body like in some insects."},{"Start":"00:35.205 ","End":"00:36.990","Text":"What would be the answer?"},{"Start":"00:36.990 ","End":"00:38.670","Text":"Does it help the animal faster?"},{"Start":"00:38.670 ","End":"00:40.305","Text":"No, certainly not."},{"Start":"00:40.305 ","End":"00:47.205","Text":"They do have a heart and it doesn\u0027t really help them develop,"},{"Start":"00:47.205 ","End":"00:54.705","Text":"but they do use less metabolic energy because the blood simply"},{"Start":"00:54.705 ","End":"01:03.180","Text":"diffuses back through or moves back to the heart by the movements of the animal."},{"Start":"01:03.180 ","End":"01:08.400","Text":"This blood, which is called the hemolymph moves back"},{"Start":"01:08.400 ","End":"01:13.575","Text":"towards into the heart and then goes out."},{"Start":"01:13.575 ","End":"01:16.665","Text":"The system is open for that reason."},{"Start":"01:16.665 ","End":"01:23.650","Text":"The answer to our question then is going to be that they use less metabolic energy."}],"ID":30912},{"Watched":false,"Name":"Exercise 2","Duration":"1m ","ChapterTopicVideoID":29073,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.950","Text":"Some animals use diffusion instead of a circulatory system."},{"Start":"00:04.950 ","End":"00:07.710","Text":"So they don\u0027t have a circulatory system."},{"Start":"00:07.710 ","End":"00:15.690","Text":"Examples of these that do not have the circulatory system are birds and jellyfish?"},{"Start":"00:15.690 ","End":"00:20.199","Text":"Birds certainly have a circulatory system,"},{"Start":"00:20.199 ","End":"00:22.695","Text":"so that can\u0027t possibly be the answer."},{"Start":"00:22.695 ","End":"00:26.460","Text":"How about flatworms and arthropods?"},{"Start":"00:26.460 ","End":"00:28.110","Text":"If you remember,"},{"Start":"00:28.110 ","End":"00:32.300","Text":"these flatworms do have"},{"Start":"00:32.300 ","End":"00:38.539","Text":"a circulatory system and the blood flow is unidirectional,"},{"Start":"00:38.539 ","End":"00:41.475","Text":"so that\u0027s not going to be the answer."},{"Start":"00:41.475 ","End":"00:45.170","Text":"As we said, these are found in earthworms, vertebrates,"},{"Start":"00:45.170 ","End":"00:47.050","Text":"and some mollusks,"},{"Start":"00:47.050 ","End":"00:50.415","Text":"for example, squids and octopi."},{"Start":"00:50.415 ","End":"00:56.770","Text":"Mollusks do have the circulatory system so that can\u0027t be the answer,"},{"Start":"00:56.770 ","End":"01:00.180","Text":"and so the answer is none of the above."}],"ID":30913},{"Watched":false,"Name":"Exercise 3","Duration":"45s","ChapterTopicVideoID":29074,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.580","Text":"Blood flow that is directed through the lungs and back to the heart."},{"Start":"00:05.580 ","End":"00:07.620","Text":"We\u0027ve got blood flow going through"},{"Start":"00:07.620 ","End":"00:16.890","Text":"the lungs and the heart is called unidirectional circulation."},{"Start":"00:16.890 ","End":"00:19.622","Text":"Is it unidirectional?"},{"Start":"00:19.622 ","End":"00:22.140","Text":"Is it Gil circulation,"},{"Start":"00:22.140 ","End":"00:28.625","Text":"pulmonary circulation or pulmocutaneous circulation?"},{"Start":"00:28.625 ","End":"00:30.229","Text":"We\u0027re going through lungs."},{"Start":"00:30.229 ","End":"00:35.785","Text":"Remember lungs is pulmonary so that\u0027s going to be our answer."},{"Start":"00:35.785 ","End":"00:39.435","Text":"Pulmonary, you have the pulmonary vein,"},{"Start":"00:39.435 ","End":"00:44.920","Text":"pulmonary artery that\u0027s through the lungs so that\u0027s our answer."}],"ID":30914},{"Watched":false,"Name":"Exercise 4","Duration":"1m ","ChapterTopicVideoID":29075,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:09.240","Text":"White blood cells can be classified as granulocytes or agranulocytes."},{"Start":"00:10.970 ","End":"00:15.900","Text":"Defend the body against bacteria and viruses are also"},{"Start":"00:15.900 ","End":"00:20.220","Text":"called leukocytes or all of the above."},{"Start":"00:20.220 ","End":"00:21.945","Text":"Well, if you remember,"},{"Start":"00:21.945 ","End":"00:27.570","Text":"they are certainly called both granulocytes and agranulocytes."},{"Start":"00:27.570 ","End":"00:29.640","Text":"See from this figure."},{"Start":"00:29.640 ","End":"00:31.605","Text":"That\u0027s going to be a correct answer,"},{"Start":"00:31.605 ","End":"00:34.320","Text":"right there certainly lymphocytes."},{"Start":"00:34.320 ","End":"00:36.060","Text":"B and T cell lymphocytes,"},{"Start":"00:36.060 ","End":"00:38.250","Text":"those are also white blood cells,"},{"Start":"00:38.250 ","End":"00:40.230","Text":"and what do they do?"},{"Start":"00:40.230 ","End":"00:43.225","Text":"They differentiate to macrophages and"},{"Start":"00:43.225 ","End":"00:48.250","Text":"dendritic cells and they respond to infection or injury."},{"Start":"00:48.250 ","End":"00:52.835","Text":"They do defend the body against bacteria and viruses,"},{"Start":"00:52.835 ","End":"00:57.380","Text":"and they are also called leukocytes as we just saw."},{"Start":"00:57.380 ","End":"01:01.410","Text":"All of the above is going to be our answer."}],"ID":30915},{"Watched":false,"Name":"Exercise 5","Duration":"58s","ChapterTopicVideoID":29076,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.545","Text":"Platelet plug formation occurs at which point?"},{"Start":"00:04.545 ","End":"00:07.140","Text":"Plug formation."},{"Start":"00:07.140 ","End":"00:08.895","Text":"What\u0027s that going to fix?"},{"Start":"00:08.895 ","End":"00:15.434","Text":"When large megakaryocytes break up into thousands of smaller fragments,"},{"Start":"00:15.434 ","End":"00:18.734","Text":"when platelets are dispersed throughout the bloodstream,"},{"Start":"00:18.734 ","End":"00:26.955","Text":"when platelets are attracted to a site of blood vessel damage or is it none of the above?"},{"Start":"00:26.955 ","End":"00:30.030","Text":"Well, if you remember,"},{"Start":"00:30.030 ","End":"00:32.715","Text":"what do platelets do?"},{"Start":"00:32.715 ","End":"00:36.809","Text":"They are attracted to the site of blood vessel damage,"},{"Start":"00:36.809 ","End":"00:40.640","Text":"so here\u0027s the blood vessel damage for instance,"},{"Start":"00:40.640 ","End":"00:42.785","Text":"and they\u0027re attracted to that area."},{"Start":"00:42.785 ","End":"00:47.885","Text":"They release fibrin and they seal the blood vessel wall."},{"Start":"00:47.885 ","End":"00:51.405","Text":"This is the damaged area."},{"Start":"00:51.405 ","End":"00:58.380","Text":"Our answer is going to be when platelets are attracted to a site of blood vessel damage."}],"ID":30916},{"Watched":false,"Name":"Exercise 6","Duration":"34s","ChapterTopicVideoID":29077,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.683","Text":"In humans, the plasma of the blood comprises what percentage of the blood?"},{"Start":"00:06.683 ","End":"00:10.065","Text":"45, 55, 25 or 90?"},{"Start":"00:10.065 ","End":"00:11.880","Text":"Well, it\u0027s about half."},{"Start":"00:11.880 ","End":"00:14.085","Text":"It\u0027s actually a little bit more than half."},{"Start":"00:14.085 ","End":"00:17.070","Text":"If you remember, this figure,"},{"Start":"00:17.070 ","End":"00:22.830","Text":"the plasma is 55 percent of the blood."},{"Start":"00:22.830 ","End":"00:27.210","Text":"It contains water, proteins, nutrients, salts, metabolites."},{"Start":"00:27.210 ","End":"00:34.540","Text":"In fact, it contains everything except the cells and platelets, the solid components."}],"ID":30917},{"Watched":false,"Name":"Exercise 7","Duration":"1m 30s","ChapterTopicVideoID":29067,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.180","Text":"The red blood cells of birds differ from mammalian red blood cells."},{"Start":"00:06.180 ","End":"00:08.040","Text":"How? In what way?"},{"Start":"00:08.040 ","End":"00:13.260","Text":"We\u0027re talking about red blood cells in birds and mammals."},{"Start":"00:13.260 ","End":"00:17.505","Text":"The red blood cells of birds they are white and have nuclei,"},{"Start":"00:17.505 ","End":"00:22.380","Text":"or they don\u0027t have nuclei in birds,"},{"Start":"00:22.380 ","End":"00:28.800","Text":"or they do have nuclei in birds but they\u0027re not white,"},{"Start":"00:28.800 ","End":"00:31.190","Text":"or they fight disease?"},{"Start":"00:31.190 ","End":"00:32.870","Text":"Well, the answer,"},{"Start":"00:32.870 ","End":"00:34.760","Text":"of course, is that they have nuclei."},{"Start":"00:34.760 ","End":"00:37.925","Text":"If you remember this slide,"},{"Start":"00:37.925 ","End":"00:41.180","Text":"we said that in birds and non-avian reptiles,"},{"Start":"00:41.180 ","End":"00:44.870","Text":"the nucleus is still maintained and that allows them to"},{"Start":"00:44.870 ","End":"00:49.235","Text":"divide by mitosis and that\u0027s the way that they reproduce."},{"Start":"00:49.235 ","End":"00:54.155","Text":"In mammals, we have this very complicated system of"},{"Start":"00:54.155 ","End":"00:59.540","Text":"producing new red blood cells and for that purpose,"},{"Start":"00:59.540 ","End":"01:02.315","Text":"if you remember, the red blood cells disintegrate,"},{"Start":"01:02.315 ","End":"01:08.270","Text":"but the iron is recycled back into new erythrocytes"},{"Start":"01:08.270 ","End":"01:15.890","Text":"and by this system or by this process called erythropoiesis."},{"Start":"01:15.890 ","End":"01:19.370","Text":"So our answer is that the red blood cells of birds differ"},{"Start":"01:19.370 ","End":"01:22.985","Text":"from mammalian red blood cells because they have nuclei."},{"Start":"01:22.985 ","End":"01:30.090","Text":"The bird red blood cells do have nuclei as opposed to mammalian ones."}],"ID":30918},{"Watched":false,"Name":"Exercise 8","Duration":"1m 13s","ChapterTopicVideoID":29337,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.110 ","End":"00:05.790","Text":"The heart\u0027s internal pacemaker beats how?"},{"Start":"00:05.790 ","End":"00:08.820","Text":"Beats by an internal implant?"},{"Start":"00:08.820 ","End":"00:11.220","Text":"An implant is usually something that\u0027s put in from the outside that"},{"Start":"00:11.220 ","End":"00:14.200","Text":"sends an electrical impulse to the heart."},{"Start":"00:14.200 ","End":"00:17.535","Text":"The excitation of cardiac muscle cells at"},{"Start":"00:17.535 ","End":"00:24.105","Text":"the sinoatrial node followed by the atrial ventricle node?"},{"Start":"00:24.105 ","End":"00:31.935","Text":"That sounds possible, which is first the sinoatrial or the atrial ventricle."},{"Start":"00:31.935 ","End":"00:34.050","Text":"The excitation of cardiac muscle cells,"},{"Start":"00:34.050 ","End":"00:37.215","Text":"the atrial ventral followed by the sinoatrial node,"},{"Start":"00:37.215 ","End":"00:39.995","Text":"or by the action of the sinus?"},{"Start":"00:39.995 ","End":"00:43.940","Text":"It\u0027s got to be one of b or c. Let\u0027s remember what happens first."},{"Start":"00:43.940 ","End":"00:45.200","Text":"Is that the atrium,"},{"Start":"00:45.200 ","End":"00:47.705","Text":"and then the ventricle that works?"},{"Start":"00:47.705 ","End":"00:49.625","Text":"Or is it the other way around?"},{"Start":"00:49.625 ","End":"00:54.275","Text":"Let\u0027s see. Of course it\u0027s the atrial that works first."},{"Start":"00:54.275 ","End":"00:57.650","Text":"We first have the atrium that is"},{"Start":"00:57.650 ","End":"01:01.355","Text":"going to have to contract moving the blood into the ventricle,"},{"Start":"01:01.355 ","End":"01:06.770","Text":"and so we have first the atrial ventral node,"},{"Start":"01:06.770 ","End":"01:09.845","Text":"and then the ventricle node."},{"Start":"01:09.845 ","End":"01:13.780","Text":"So our answer is b."}],"ID":30919},{"Watched":false,"Name":"Exercise 9","Duration":"40s","ChapterTopicVideoID":29068,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.150","Text":"During the systolic phase of the cardiac cycle,"},{"Start":"00:06.150 ","End":"00:13.845","Text":"what\u0027s it doing is the systolic phase is contracting and relaxing,"},{"Start":"00:13.845 ","End":"00:15.810","Text":"or is it filling with blood?"},{"Start":"00:15.810 ","End":"00:17.550","Text":"Well, it\u0027s going to be contracting."},{"Start":"00:17.550 ","End":"00:22.410","Text":"If you remember during the systolic phase,"},{"Start":"00:22.410 ","End":"00:24.570","Text":"that\u0027s the contraction phase,"},{"Start":"00:24.570 ","End":"00:27.135","Text":"blood is pushed through the body."},{"Start":"00:27.135 ","End":"00:30.030","Text":"That\u0027s the systolic phase."},{"Start":"00:30.030 ","End":"00:35.700","Text":"Our answer is going to be during the systolic phase,"},{"Start":"00:35.700 ","End":"00:38.800","Text":"the heart is contracting, a."}],"ID":30920},{"Watched":false,"Name":"Exercise 10","Duration":"1m 3s","ChapterTopicVideoID":29069,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:07.905","Text":"Cardiomyocytes are similar to skeletal muscle because they beat involuntarily."},{"Start":"00:07.905 ","End":"00:10.470","Text":"Because they are used for weight lifting."},{"Start":"00:10.470 ","End":"00:12.660","Text":"Cardiomyocytes and skeletal muscles,"},{"Start":"00:12.660 ","End":"00:18.540","Text":"cardiomyocytes, they pulse rhythmically or they are striated."},{"Start":"00:18.540 ","End":"00:21.105","Text":"Well, if you remember,"},{"Start":"00:21.105 ","End":"00:25.440","Text":"the answer to that is going to be that they are striated."},{"Start":"00:25.440 ","End":"00:28.605","Text":"In fact, they both beat involuntarily."},{"Start":"00:28.605 ","End":"00:31.200","Text":"They\u0027re both used for weight lifting because"},{"Start":"00:31.200 ","End":"00:34.095","Text":"you have both use your heart and your skeletal muscles."},{"Start":"00:34.095 ","End":"00:40.470","Text":"Well, actually they don\u0027t pulse rhythmically,"},{"Start":"00:40.470 ","End":"00:47.220","Text":"of course, because only the heart beats rhythmically, but both of them are striated."},{"Start":"00:48.080 ","End":"00:50.470","Text":"Both of them are striated."},{"Start":"00:50.470 ","End":"00:52.610","Text":"If you remember this picture,"},{"Start":"00:52.610 ","End":"00:56.180","Text":"they are both striated."},{"Start":"00:56.180 ","End":"00:59.210","Text":"Cardiomyocytes are striated like skeletal muscle,"},{"Start":"00:59.210 ","End":"01:03.540","Text":"so that\u0027s going to be our answer. D."}],"ID":30921},{"Watched":false,"Name":"Exercise 11","Duration":"1m 3s","ChapterTopicVideoID":29070,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.049","Text":"How do arteries differ from veins?"},{"Start":"00:04.049 ","End":"00:06.360","Text":"Differences between arteries and veins."},{"Start":"00:06.360 ","End":"00:08.730","Text":"Arteries have thicker smooth muscle layers to"},{"Start":"00:08.730 ","End":"00:11.580","Text":"accommodate the changes in pressure from the heart."},{"Start":"00:11.580 ","End":"00:14.910","Text":"Sounds interesting. Arteries carry blood."},{"Start":"00:14.910 ","End":"00:18.255","Text":"Well, they do, but that\u0027s not how they different from veins."},{"Start":"00:18.255 ","End":"00:22.170","Text":"Arteries have thinner smooth muscle layers"},{"Start":"00:22.170 ","End":"00:25.410","Text":"and valves and move the blood by action of skeletal muscle."},{"Start":"00:25.410 ","End":"00:28.995","Text":"Well, arteries don\u0027t have valves."},{"Start":"00:28.995 ","End":"00:30.510","Text":"Veins have valves."},{"Start":"00:30.510 ","End":"00:31.860","Text":"That\u0027s not going to be our answer."},{"Start":"00:31.860 ","End":"00:35.355","Text":"Arteries are thin-walled and are used for gas exchange."},{"Start":"00:35.355 ","End":"00:37.545","Text":"No, that\u0027s capillaries."},{"Start":"00:37.545 ","End":"00:40.680","Text":"Let\u0027s say this is going to be an easy one."},{"Start":"00:40.680 ","End":"00:47.524","Text":"The arteries have thick walls and the veins,"},{"Start":"00:47.524 ","End":"00:50.450","Text":"from this slide it says that they are thinner walled as the pressure and"},{"Start":"00:50.450 ","End":"00:54.190","Text":"rate of blood flow are much lower than in arteries."},{"Start":"00:54.190 ","End":"00:56.780","Text":"Our answer is going to be that arteries have"},{"Start":"00:56.780 ","End":"01:02.820","Text":"thicker smooth muscle layers to accommodate the changes in pressure from the heart."}],"ID":30922},{"Watched":false,"Name":"Exercise 12","Duration":"1m 9s","ChapterTopicVideoID":29071,"CourseChapterTopicPlaylistID":294423,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.820","Text":"High blood pressure would be a result of which?"},{"Start":"00:04.820 ","End":"00:08.325","Text":"We\u0027re talking about high blood pressure,"},{"Start":"00:08.325 ","End":"00:13.215","Text":"high cardiac output, and high peripheral resistance?"},{"Start":"00:13.215 ","End":"00:17.414","Text":"High cardiac output and low peripheral resistance?"},{"Start":"00:17.414 ","End":"00:19.485","Text":"Low cardiac output?"},{"Start":"00:19.485 ","End":"00:22.530","Text":"Well, both of these second ones have low cardiac output,"},{"Start":"00:22.530 ","End":"00:26.445","Text":"it has to be from high cardiac output."},{"Start":"00:26.445 ","End":"00:33.750","Text":"But high cardiac output and low peripheral resistance would make the pressure lower."},{"Start":"00:33.750 ","End":"00:37.020","Text":"Our answer is going to have to be a."},{"Start":"00:37.020 ","End":"00:40.100","Text":"Now, let\u0027s see. If you remember,"},{"Start":"00:40.100 ","End":"00:44.960","Text":"peripheral resistance is the resistance that must be overcome to push"},{"Start":"00:44.960 ","End":"00:50.170","Text":"blood through the circulatory system and to create the flow."},{"Start":"00:50.170 ","End":"00:52.505","Text":"If the peripheral resistance is high,"},{"Start":"00:52.505 ","End":"00:59.430","Text":"that would raise our blood pressure."},{"Start":"00:59.430 ","End":"01:03.785","Text":"So our answer to this question therefore is going to be a,"},{"Start":"01:03.785 ","End":"01:08.940","Text":"high cardiac output and high peripheral resistance."}],"ID":30923}],"Thumbnail":null,"ID":294423}]

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