[{"Name":"Animal Form and Function","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Symmetry of form","Duration":"5m 49s","ChapterTopicVideoID":26910,"CourseChapterTopicPlaylistID":261502,"HasSubtitles":true,"ThumbnailPath":"https://www.proprep.uk/Images/Videos_Thumbnails/26910.jpeg","UploadDate":"2021-10-21T06:31:17.3370000","DurationForVideoObject":"PT5M49S","Description":null,"MetaTitle":"Symmetry of form: Video + Workbook | Proprep","MetaDescription":"The Animal Body Basic Form and Function - Animal Form and Function. Watch the video made by an expert in the field. Download the workbook and maximize your learning.","Canonical":"https://www.proprep.uk/general-modules/all/introduction-to-biology/the-animal-body-basic-form-and-function/animal-form-and-function/vid28000","VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.250","Text":"Hi. In this end,"},{"Start":"00:02.250 ","End":"00:03.510","Text":"in the coming videos,"},{"Start":"00:03.510 ","End":"00:07.575","Text":"we\u0027re going to talk about animal form and function"},{"Start":"00:07.575 ","End":"00:12.540","Text":"and discuss the different kinds of forms that we see in animals."},{"Start":"00:12.540 ","End":"00:13.860","Text":"I mean, you can see here for instance,"},{"Start":"00:13.860 ","End":"00:16.485","Text":"you\u0027ve got this big elephant and you\u0027ve got"},{"Start":"00:16.485 ","End":"00:20.950","Text":"a smaller hyenas and birds of different sizes."},{"Start":"00:20.950 ","End":"00:23.715","Text":"All different shapes, sizes."},{"Start":"00:23.715 ","End":"00:28.279","Text":"Those differences are certainly going to relate to their function."},{"Start":"00:28.279 ","End":"00:30.345","Text":"Let\u0027s invest the gate that."},{"Start":"00:30.345 ","End":"00:36.660","Text":"To begin with, animals bodies vary in form and function. That\u0027s what we saw."},{"Start":"00:36.660 ","End":"00:38.420","Text":"If you look at this picture, for instance,"},{"Start":"00:38.420 ","End":"00:42.020","Text":"you can see this Galapagos tortoise,"},{"Start":"00:42.020 ","End":"00:49.205","Text":"which lives out in a very wooded and grassy area in the Galapagos is enormous,"},{"Start":"00:49.205 ","End":"00:52.475","Text":"and it\u0027s got a very large shell."},{"Start":"00:52.475 ","End":"00:54.680","Text":"But if you look into the inside,"},{"Start":"00:54.680 ","End":"01:01.220","Text":"you\u0027ll see that there are some things that are conserved with other animals that we know."},{"Start":"01:01.220 ","End":"01:04.406","Text":"For instance, it has inside of it,"},{"Start":"01:04.406 ","End":"01:13.015","Text":"it has a spinal cord but it\u0027s adapted to its surroundings."},{"Start":"01:13.015 ","End":"01:20.675","Text":"The anatomy that\u0027s the organisms form has to match the physiology."},{"Start":"01:20.675 ","End":"01:25.035","Text":"The physiology which is the function that it performance."},{"Start":"01:25.035 ","End":"01:31.100","Text":"Therefore the animals bodies are designed to interact with their environments."},{"Start":"01:31.100 ","End":"01:34.910","Text":"That\u0027s what\u0027s going to control their anatomy,"},{"Start":"01:34.910 ","End":"01:38.150","Text":"the physiology that they need."},{"Start":"01:38.150 ","End":"01:42.200","Text":"Furthermore, we can understand a lot about"},{"Start":"01:42.200 ","End":"01:48.305","Text":"the organism\u0027s anatomy simply by looking at the environment in which an organism lives,"},{"Start":"01:48.305 ","End":"01:54.259","Text":"and then trying to understand about how the anatomy fits the environment."},{"Start":"01:54.259 ","End":"01:59.180","Text":"Let\u0027s now look at different forms."},{"Start":"01:59.180 ","End":"02:01.520","Text":"To begin with, we\u0027ll think about it in"},{"Start":"02:01.520 ","End":"02:07.355","Text":"a more abstract way and discuss different body plans."},{"Start":"02:07.355 ","End":"02:11.075","Text":"An animal\u0027s body plan will"},{"Start":"02:11.075 ","End":"02:15.935","Text":"follow a certain set of patterns that have to do with symmetry."},{"Start":"02:15.935 ","End":"02:22.715","Text":"Usually, not always because some of the body plans can be asymmetrical,"},{"Start":"02:22.715 ","End":"02:29.330","Text":"as in this coral that we might find under the sea, it\u0027s asymmetrical."},{"Start":"02:29.330 ","End":"02:32.380","Text":"There\u0027s really no pattern or symmetry."},{"Start":"02:32.380 ","End":"02:36.860","Text":"It\u0027s actually a sponge that\u0027s under the sea and we"},{"Start":"02:36.860 ","End":"02:41.825","Text":"can\u0027t really determinate very precise symmetry."},{"Start":"02:41.825 ","End":"02:46.685","Text":"On the other hand, we can look at something called radial symmetry."},{"Start":"02:46.685 ","End":"02:52.670","Text":"There are some organisms like this organism that we have here, and it\u0027s radial."},{"Start":"02:52.670 ","End":"02:57.320","Text":"That means that we can cut it in every direction and we\u0027ll see"},{"Start":"02:57.320 ","End":"03:03.355","Text":"symmetry in every direction but from a particular point."},{"Start":"03:03.355 ","End":"03:05.250","Text":"Yes, it goes down in this case."},{"Start":"03:05.250 ","End":"03:07.145","Text":"We can put planes through it."},{"Start":"03:07.145 ","End":"03:11.570","Text":"Which way? Many different planes in every plane that we put through it."},{"Start":"03:11.570 ","End":"03:14.900","Text":"Yes, we\u0027ll see symmetry through all of them."},{"Start":"03:14.900 ","End":"03:17.780","Text":"That\u0027ll be called radial symmetry."},{"Start":"03:17.780 ","End":"03:21.110","Text":"Then we can look at something called bilateral symmetry."},{"Start":"03:21.110 ","End":"03:22.580","Text":"In bilateral symmetry,"},{"Start":"03:22.580 ","End":"03:26.090","Text":"we\u0027ll put 1 plane down through it."},{"Start":"03:26.090 ","End":"03:31.070","Text":"In that case, the animal will be separated into right"},{"Start":"03:31.070 ","End":"03:36.320","Text":"and left sides or front and back sides, different sides."},{"Start":"03:36.320 ","End":"03:40.910","Text":"In this case, if we\u0027re looking at this bilateral symmetry,"},{"Start":"03:40.910 ","End":"03:44.270","Text":"that plane cut from front to back."},{"Start":"03:44.270 ","End":"03:46.640","Text":"This is the plane that\u0027s shown over here."},{"Start":"03:46.640 ","End":"03:51.620","Text":"Then the animal definitely has right and left sides and this enables"},{"Start":"03:51.620 ","End":"03:56.710","Text":"a high level of mobility because the front and the back act differently."},{"Start":"03:56.710 ","End":"03:58.820","Text":"It can push off,"},{"Start":"03:58.820 ","End":"04:01.820","Text":"for instance with the ventral side,"},{"Start":"04:01.820 ","End":"04:06.032","Text":"the back legs, and grab on with the front legs."},{"Start":"04:06.032 ","End":"04:09.425","Text":"This gives it a certain advantage."},{"Start":"04:09.425 ","End":"04:13.625","Text":"Now let\u0027s look at different planes."},{"Start":"04:13.625 ","End":"04:17.690","Text":"There is something called the saggital plane,"},{"Start":"04:17.690 ","End":"04:23.750","Text":"which is now going to divide the body into right and left portions."},{"Start":"04:23.750 ","End":"04:29.615","Text":"We can have a midsaggital plane which goes right down the middle."},{"Start":"04:29.615 ","End":"04:32.140","Text":"The midsaggital plane."},{"Start":"04:32.140 ","End":"04:36.635","Text":"Then we\u0027ll have an equal right and left sides."},{"Start":"04:36.635 ","End":"04:38.390","Text":"You can think of this in an animal,"},{"Start":"04:38.390 ","End":"04:40.205","Text":"you can think of it in a human."},{"Start":"04:40.205 ","End":"04:43.265","Text":"This would be this blue plane,"},{"Start":"04:43.265 ","End":"04:47.809","Text":"which makes 2 equal right and left halves."},{"Start":"04:47.809 ","End":"04:50.900","Text":"Now, let\u0027s look at the frontal plane,"},{"Start":"04:50.900 ","End":"04:53.915","Text":"which is sometimes called the coronal plane,"},{"Start":"04:53.915 ","End":"04:57.480","Text":"that separates the front from the back."},{"Start":"04:57.480 ","End":"05:00.370","Text":"That would be the yellow plane."},{"Start":"05:00.370 ","End":"05:02.375","Text":"The one that we see here,"},{"Start":"05:02.375 ","End":"05:03.990","Text":"which is going to separate,"},{"Start":"05:03.990 ","End":"05:07.835","Text":"it\u0027s easiest to see in humans, the frontal plane."},{"Start":"05:07.835 ","End":"05:10.595","Text":"Which is going to separate the front where the face would be"},{"Start":"05:10.595 ","End":"05:14.235","Text":"from the back of the organism."},{"Start":"05:14.235 ","End":"05:19.205","Text":"Another plane would be the transverse plane, the horizontal plane,"},{"Start":"05:19.205 ","End":"05:24.883","Text":"which divides the animal into upper and lower portions."},{"Start":"05:24.883 ","End":"05:30.095","Text":"That would be the red plane that separates the top here"},{"Start":"05:30.095 ","End":"05:36.275","Text":"from the bottom or the top where the head is from the back, the bottom."},{"Start":"05:36.275 ","End":"05:37.880","Text":"Of course, if we want,"},{"Start":"05:37.880 ","End":"05:41.840","Text":"we could put any old plane in that we\u0027d call an oblique plane that"},{"Start":"05:41.840 ","End":"05:46.190","Text":"might cut the animal at some sort of an angle but in that case,"},{"Start":"05:46.190 ","End":"05:49.590","Text":"we would have no symmetry."}],"ID":28000},{"Watched":false,"Name":"Cavities in vertebrates","Duration":"5m 50s","ChapterTopicVideoID":26907,"CourseChapterTopicPlaylistID":261502,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.443","Text":"In this video, we\u0027ll continue to discuss form and"},{"Start":"00:04.443 ","End":"00:08.797","Text":"function in animals and we\u0027ll concentrate on cavities."},{"Start":"00:08.797 ","End":"00:12.874","Text":"Those are spaces in which we find different organs."},{"Start":"00:12.874 ","End":"00:15.582","Text":"Those are defined body cavities."},{"Start":"00:15.582 ","End":"00:21.431","Text":"Especially vertebrate animals like us have a number of these things."},{"Start":"00:21.431 ","End":"00:23.800","Text":"There are 2 major cavities."},{"Start":"00:23.800 ","End":"00:29.046","Text":"There\u0027s the dorsal cavity and there is the ventral cavity."},{"Start":"00:29.046 ","End":"00:30.834","Text":"The dorsal cavity,"},{"Start":"00:30.834 ","End":"00:37.211","Text":"we can see is our head and what\u0027s close to the head."},{"Start":"00:37.211 ","End":"00:45.695","Text":"That includes the cranial cavity that\u0027s going to have in it our brain,"},{"Start":"00:45.695 ","End":"00:50.435","Text":"and the vertebral cavity that has the vertebrae."},{"Start":"00:50.435 ","End":"00:57.380","Text":"That of course is going to protect nervous tissue which is going to be inside."},{"Start":"00:57.380 ","End":"00:58.670","Text":"In addition to that,"},{"Start":"00:58.670 ","End":"01:05.945","Text":"we have a ventral cavity that we can also separate into 2 different cavities."},{"Start":"01:05.945 ","End":"01:10.460","Text":"There\u0027s the thoracic cavity and that\u0027s"},{"Start":"01:10.460 ","End":"01:15.145","Text":"going to include the pleural cavity that we have divided further."},{"Start":"01:15.145 ","End":"01:17.970","Text":"Pleura means lungs."},{"Start":"01:17.970 ","End":"01:20.235","Text":"We\u0027ve got what you see in blue here."},{"Start":"01:20.235 ","End":"01:21.905","Text":"In addition to that,"},{"Start":"01:21.905 ","End":"01:27.965","Text":"we have the mediastinum and the pericardial cavity."},{"Start":"01:27.965 ","End":"01:33.110","Text":"Of course, those have to do with our hearts primarily."},{"Start":"01:33.110 ","End":"01:36.200","Text":"Yes, the cardia means heart."},{"Start":"01:36.200 ","End":"01:40.310","Text":"This is the cavity where we have things that are going on with"},{"Start":"01:40.310 ","End":"01:45.935","Text":"our circulatory system that are very close to the pleural cavity."},{"Start":"01:45.935 ","End":"01:51.320","Text":"Then of course, below that we have the abdominopelvic cavity,"},{"Start":"01:51.320 ","End":"01:53.660","Text":"the area which is underneath and what\u0027s in there."},{"Start":"01:53.660 ","End":"01:56.375","Text":"That of course consists of"},{"Start":"01:56.375 ","End":"02:01.130","Text":"the abdominal cavity where we have our abdomen and we have our intestines,"},{"Start":"02:01.130 ","End":"02:02.405","Text":"stomach and so on,"},{"Start":"02:02.405 ","End":"02:08.540","Text":"and the pelvic cavity in females especially,"},{"Start":"02:08.540 ","End":"02:16.475","Text":"contains reproductive organism organs such as the uterus in people."},{"Start":"02:16.475 ","End":"02:22.760","Text":"But in any case, these cavities that there are in various places demonstrate to"},{"Start":"02:22.760 ","End":"02:29.120","Text":"us that there is a hierarchical organization of body plans."},{"Start":"02:29.120 ","End":"02:34.820","Text":"Because we know that the organism certainly is made up of atoms that compose of molecule,"},{"Start":"02:34.820 ","End":"02:37.196","Text":"that compose macro molecules,"},{"Start":"02:37.196 ","End":"02:39.560","Text":"that then form together to make organelles."},{"Start":"02:39.560 ","End":"02:46.550","Text":"Those organelles then come together or they are placed in particular places inside cells."},{"Start":"02:46.550 ","End":"02:50.906","Text":"The cells come together to make tissues."},{"Start":"02:50.906 ","End":"02:56.180","Text":"That\u0027s what we are concentrating on here."},{"Start":"02:56.180 ","End":"03:05.210","Text":"Those tissues then we\u0027ll make up organs that are inside a larger organ system."},{"Start":"03:05.210 ","End":"03:09.725","Text":"Sometimes, in fact we\u0027ll have some organs"},{"Start":"03:09.725 ","End":"03:15.260","Text":"that will belong to more than 1 organ systems such as the pancreas."},{"Start":"03:15.260 ","End":"03:16.970","Text":"The pancreas, for instance,"},{"Start":"03:16.970 ","End":"03:22.541","Text":"we know makes some digestive juices that go into the intestine,"},{"Start":"03:22.541 ","End":"03:27.965","Text":"but in addition to that the pancreas is also important for the immune system."},{"Start":"03:27.965 ","End":"03:32.960","Text":"It\u0027s not necessarily true that at one particular organ has 1 function."},{"Start":"03:32.960 ","End":"03:36.770","Text":"Many of them do, but others don\u0027t."},{"Start":"03:36.770 ","End":"03:41.690","Text":"Now, let\u0027s look again at form of the animals."},{"Start":"03:41.690 ","End":"03:48.875","Text":"We\u0027ll notice that the environment is going to make a big difference in the shape,"},{"Start":"03:48.875 ","End":"03:54.220","Text":"in the form of the organism as we had discussed a bit earlier."},{"Start":"03:54.220 ","End":"04:00.350","Text":"Fish and various animals and reptiles and whatnot that live inside water,"},{"Start":"04:00.350 ","End":"04:02.765","Text":"here we have fish and mammals,"},{"Start":"04:02.765 ","End":"04:06.215","Text":"and birds even that swim in water and reptiles,"},{"Start":"04:06.215 ","End":"04:11.090","Text":"they all have somewhat similar form."},{"Start":"04:11.090 ","End":"04:12.740","Text":"Why?"},{"Start":"04:12.740 ","End":"04:16.100","Text":"Because they have to deal with water."},{"Start":"04:16.100 ","End":"04:19.160","Text":"There are certain physical laws that are going"},{"Start":"04:19.160 ","End":"04:23.356","Text":"to limit what the animals can do in the water,"},{"Start":"04:23.356 ","End":"04:25.460","Text":"because they have to deal with"},{"Start":"04:25.460 ","End":"04:30.635","Text":"the movement through the water and they have to do with heat exchange in the water."},{"Start":"04:30.635 ","End":"04:37.370","Text":"The body shape of these animals is going to be shaped or is going to be"},{"Start":"04:37.370 ","End":"04:44.330","Text":"influenced really by the properties of water that are going to primarily do 2 things."},{"Start":"04:44.330 ","End":"04:48.079","Text":"One, is they\u0027re going to make sure that they\u0027re going to be buoyant."},{"Start":"04:48.079 ","End":"04:50.660","Text":"These various organisms are going to be buoyant."},{"Start":"04:50.660 ","End":"04:52.940","Text":"That means they will float in the water."},{"Start":"04:52.940 ","End":"04:57.620","Text":"They don\u0027t have to really support themselves as land animals do but the other thing they"},{"Start":"04:57.620 ","End":"05:02.830","Text":"have to do is they need to deal with the drag of the water as they move through it."},{"Start":"05:02.830 ","End":"05:10.405","Text":"That\u0027s going to cause all of these various organisms to evolve in a convergent way."},{"Start":"05:10.405 ","End":"05:16.460","Text":"There will be similar adaptations of various organisms to the same challenge,"},{"Start":"05:16.460 ","End":"05:19.100","Text":"and that\u0027s called convergent evolution."},{"Start":"05:19.100 ","End":"05:22.339","Text":"They\u0027ve all evolved in the same direction,"},{"Start":"05:22.339 ","End":"05:25.300","Text":"but not from one another."},{"Start":"05:25.300 ","End":"05:30.650","Text":"What we do know though is that animals when they increase in size,"},{"Start":"05:30.650 ","End":"05:34.685","Text":"are going to have thicker skeletons to be able to support them."},{"Start":"05:34.685 ","End":"05:39.845","Text":"That of course, is something else which is convergent evolution."},{"Start":"05:39.845 ","End":"05:41.330","Text":"In the next video,"},{"Start":"05:41.330 ","End":"05:45.260","Text":"we\u0027ll look at the limits on animal size and"},{"Start":"05:45.260 ","End":"05:51.630","Text":"shape and see how those are affected by function."}],"ID":28001},{"Watched":false,"Name":"Endoskeleton, cell size and energetics in organisms","Duration":"8m 22s","ChapterTopicVideoID":26908,"CourseChapterTopicPlaylistID":261502,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:07.780","Text":"Let\u0027s look again at animal form and function when we\u0027re talking about the skeleton."},{"Start":"00:07.780 ","End":"00:09.030","Text":"In the previous video,"},{"Start":"00:09.030 ","End":"00:13.410","Text":"we talked about the skeleton as an exoskeleton."},{"Start":"00:13.410 ","End":"00:16.815","Text":"Now let\u0027s talk about the endoskeleton."},{"Start":"00:16.815 ","End":"00:19.738","Text":"Well, there\u0027s a problem with an exoskeleton,"},{"Start":"00:19.738 ","End":"00:26.630","Text":"and that is that when the body size increases by a factor of 8,"},{"Start":"00:26.630 ","End":"00:31.019","Text":"every time, there is a doubling of body size and so"},{"Start":"00:31.019 ","End":"00:35.420","Text":"that\u0027s going to make it such that this exoskeleton will"},{"Start":"00:35.420 ","End":"00:40.520","Text":"break and not be able to hold all this weight as an animal gets older so this"},{"Start":"00:40.520 ","End":"00:47.395","Text":"limits most animals with an exoskeleton to a relatively small size."},{"Start":"00:47.395 ","End":"00:51.170","Text":"With endoskeletons, muscles, we know"},{"Start":"00:51.170 ","End":"00:54.814","Text":"instead of being attached on the inside of the skeleton,"},{"Start":"00:54.814 ","End":"00:58.676","Text":"they\u0027re attached to the outside of the skeleton."},{"Start":"00:58.676 ","End":"01:05.345","Text":"That helps compensate for the increased mass of larger organisms."},{"Start":"01:05.345 ","End":"01:09.410","Text":"The size of an animal with an endoskeleton, therefore,"},{"Start":"01:09.410 ","End":"01:14.390","Text":"is determined by the amount of the skeletal system that it needs in order to"},{"Start":"01:14.390 ","End":"01:21.060","Text":"support these other tissues and the amount of muscle that it needs for movement."},{"Start":"01:21.060 ","End":"01:27.110","Text":"The larger animals are going to have endoskeletons that is skeletons,"},{"Start":"01:27.110 ","End":"01:28.760","Text":"that are on the inside."},{"Start":"01:28.760 ","End":"01:33.020","Text":"Of course, as the body size increases,"},{"Start":"01:33.020 ","End":"01:37.550","Text":"both the bone and the muscle mass will increase."},{"Start":"01:37.550 ","End":"01:43.445","Text":"Now let\u0027s look at another aspect of form and function."},{"Start":"01:43.445 ","End":"01:48.320","Text":"Let\u0027s ask the question about what happens when an animal gets bigger,"},{"Start":"01:48.320 ","End":"01:54.705","Text":"do the cells get bigger or do the number of cells increase?"},{"Start":"01:54.705 ","End":"01:59.390","Text":"Of course, the answer is that the number of cells increases,"},{"Start":"01:59.390 ","End":"02:02.410","Text":"but the reason for that is really physical,"},{"Start":"02:02.410 ","End":"02:08.000","Text":"and that we can see in this picture because if we say that this,"},{"Start":"02:08.000 ","End":"02:14.105","Text":"let\u0027s say is a cell that let\u0027s say has 6 sides to it, it\u0027d be a cube,"},{"Start":"02:14.105 ","End":"02:20.200","Text":"would say if it has a volume of one cubic units,"},{"Start":"02:20.200 ","End":"02:25.280","Text":"then it would have a surface area of six square units."},{"Start":"02:25.280 ","End":"02:31.115","Text":"Whereas if we have the same cubic volume it\u0027s divided up into 1,"},{"Start":"02:31.115 ","End":"02:32.555","Text":"2, 3, 4,"},{"Start":"02:32.555 ","End":"02:34.265","Text":"5, 6, 7,"},{"Start":"02:34.265 ","End":"02:37.130","Text":"8 by 8 cells,"},{"Start":"02:37.130 ","End":"02:43.355","Text":"then we would have a surface area of 384 square units."},{"Start":"02:43.355 ","End":"02:49.730","Text":"That\u0027s a lot more surface area for the same general volume."},{"Start":"02:49.730 ","End":"02:51.660","Text":"Now, why is that important?"},{"Start":"02:51.660 ","End":"02:56.900","Text":"Because small unicellular organisms get their nutrients through diffusion"},{"Start":"02:56.900 ","End":"03:02.627","Text":"and therefore cell size has to be constrained by surface area volume."},{"Start":"03:02.627 ","End":"03:08.660","Text":"You can\u0027t have a single organism or a single cell which is going to be very,"},{"Start":"03:08.660 ","End":"03:15.475","Text":"very large because the rate of diffusion in and out of this will be too slow."},{"Start":"03:15.475 ","End":"03:18.440","Text":"That is because as we just said,"},{"Start":"03:18.440 ","End":"03:20.090","Text":"as the cell gets larger,"},{"Start":"03:20.090 ","End":"03:25.700","Text":"the ratio of the surface area to the volume decreases,"},{"Start":"03:25.700 ","End":"03:28.003","Text":"and that\u0027s not a good thing,"},{"Start":"03:28.003 ","End":"03:29.840","Text":"with the reason I just explained."},{"Start":"03:29.840 ","End":"03:33.895","Text":"Larger organisms have more cells,"},{"Start":"03:33.895 ","End":"03:42.375","Text":"not larger cells, and they are therefore multicellular organisms."},{"Start":"03:42.375 ","End":"03:48.065","Text":"This must therefore provide the nutrients and oxygen to all the cells,"},{"Start":"03:48.065 ","End":"03:51.200","Text":"with very specialized cells, for instance,"},{"Start":"03:51.200 ","End":"03:58.250","Text":"there are blood vessels which can go in between these cells and deliver the oxygen,"},{"Start":"03:58.250 ","End":"04:03.020","Text":"the nutrients that carry away the waste products as is necessary so"},{"Start":"04:03.020 ","End":"04:07.995","Text":"that the organs and organ systems work well together."},{"Start":"04:07.995 ","End":"04:16.440","Text":"Another physical aspect that we need to deal with is the heat aspect of the organism."},{"Start":"04:16.440 ","End":"04:19.070","Text":"The bioenergetics."},{"Start":"04:19.070 ","End":"04:25.235","Text":"The energy from nutrients is used in the animal body to fuel anabolic reactions."},{"Start":"04:25.235 ","End":"04:27.155","Text":"What are anabolic reactions?"},{"Start":"04:27.155 ","End":"04:31.025","Text":"Those are reactions that build the things that"},{"Start":"04:31.025 ","End":"04:36.130","Text":"make the organism bigger or to regenerate organs."},{"Start":"04:36.130 ","End":"04:39.810","Text":"We know that there are two kinds of organisms,"},{"Start":"04:39.810 ","End":"04:42.585","Text":"they\u0027re the kinds that control their own temperature."},{"Start":"04:42.585 ","End":"04:44.430","Text":"As the ambient temperature,"},{"Start":"04:44.430 ","End":"04:47.060","Text":"the temperature around the animal changes,"},{"Start":"04:47.060 ","End":"04:51.800","Text":"the temperature of the animal itself does not change hardly."},{"Start":"04:51.800 ","End":"04:55.520","Text":"Whereas there are other kinds of organisms like say snakes, reptiles,"},{"Start":"04:55.520 ","End":"05:02.100","Text":"and things of that sort that do not control their own temperature,"},{"Start":"05:02.100 ","End":"05:03.965","Text":"and as the temperature goes up,"},{"Start":"05:03.965 ","End":"05:07.370","Text":"so does the temperature of the organism."},{"Start":"05:07.370 ","End":"05:12.405","Text":"How does a endothermic animal handle that?"},{"Start":"05:12.405 ","End":"05:15.709","Text":"Well, there is a basal metabolic rate."},{"Start":"05:15.709 ","End":"05:19.860","Text":"Well, both of these animals have a basic metabolic rate,"},{"Start":"05:19.860 ","End":"05:25.490","Text":"and that is the average amount of energy used by an organism when it\u0027s not active,"},{"Start":"05:25.490 ","End":"05:27.555","Text":"just to keep it moving."},{"Start":"05:27.555 ","End":"05:33.640","Text":"The excess energy that it produces this way is given off as heat."},{"Start":"05:33.640 ","End":"05:38.420","Text":"What\u0027s endothermic animals do is they control"},{"Start":"05:38.420 ","End":"05:42.230","Text":"their basic metabolic rate so that it is"},{"Start":"05:42.230 ","End":"05:47.750","Text":"appropriate with their activity and therefore the energy stays the same."},{"Start":"05:47.750 ","End":"05:50.588","Text":"Those are endotherms,"},{"Start":"05:50.588 ","End":"05:57.170","Text":"that animal conserves this heat and maintains a relatively constant body temperature."},{"Start":"05:57.170 ","End":"06:02.450","Text":"Whereas ectotherms that we discussed before like the snakes,"},{"Start":"06:02.450 ","End":"06:07.415","Text":"depends on the surroundings for body heats."},{"Start":"06:07.415 ","End":"06:13.460","Text":"The energy is also related to body size because the BMR,"},{"Start":"06:13.460 ","End":"06:15.920","Text":"this basic metabolic rate,"},{"Start":"06:15.920 ","End":"06:22.445","Text":"is faster typically in smaller animals than is in large ones."},{"Start":"06:22.445 ","End":"06:24.470","Text":"You can see this down here,"},{"Start":"06:24.470 ","End":"06:28.880","Text":"the differences can be quite enormous, and therefore,"},{"Start":"06:28.880 ","End":"06:36.050","Text":"smaller organisms require more energy to maintain a constant internal temperature."},{"Start":"06:36.050 ","End":"06:38.630","Text":"Active animals, of course,"},{"Start":"06:38.630 ","End":"06:42.800","Text":"have a higher BMR than inactive ones"},{"Start":"06:42.800 ","End":"06:47.560","Text":"because they\u0027re using a lot of their energy for their activity."},{"Start":"06:47.560 ","End":"06:49.894","Text":"How is this determined?"},{"Start":"06:49.894 ","End":"06:52.984","Text":"It\u0027s determined by the diet."},{"Start":"06:52.984 ","End":"06:59.630","Text":"The diet of an endothermic animal is going to be determined by its BMR."},{"Start":"06:59.630 ","End":"07:04.110","Text":"Finally, what about resting?"},{"Start":"07:04.110 ","End":"07:06.559","Text":"Well, sometimes animals,"},{"Start":"07:06.559 ","End":"07:08.540","Text":"even hummingbirds that have had a very,"},{"Start":"07:08.540 ","End":"07:11.840","Text":"very high basic metabolism rates,"},{"Start":"07:11.840 ","End":"07:14.530","Text":"a very high BMR, need to rest."},{"Start":"07:14.530 ","End":"07:19.640","Text":"They\u0027ll do this by decreasing their activity in something that\u0027s called torpor."},{"Start":"07:19.640 ","End":"07:23.210","Text":"In fact, even their body temperature may go down and this"},{"Start":"07:23.210 ","End":"07:27.350","Text":"saves energy by avoiding difficult and dangerous conditions."},{"Start":"07:27.350 ","End":"07:31.670","Text":"This can occur even daily in small animals and birds,"},{"Start":"07:31.670 ","End":"07:36.950","Text":"whereas other organisms have this thing called hibernation, for instance,"},{"Start":"07:36.950 ","End":"07:40.010","Text":"in which during the winter they will hibernate,"},{"Start":"07:40.010 ","End":"07:43.400","Text":"they\u0027ll stay in one place, bears, you know,"},{"Start":"07:43.400 ","End":"07:46.715","Text":"do that and that involves reduction of"},{"Start":"07:46.715 ","End":"07:51.110","Text":"body temperatures so they can conserve their energy."},{"Start":"07:51.110 ","End":"07:55.580","Text":"There is another situation in which animals have to control their temperature,"},{"Start":"07:55.580 ","End":"07:57.230","Text":"and that is if it is very,"},{"Start":"07:57.230 ","End":"08:00.320","Text":"very hot outside so in the summer months,"},{"Start":"08:00.320 ","End":"08:05.375","Text":"there\u0027s something that\u0027s opposite of hibernation, it\u0027s called estivation."},{"Start":"08:05.375 ","End":"08:07.730","Text":"The temperatures are very high,"},{"Start":"08:07.730 ","End":"08:10.890","Text":"water sources is very scarce."},{"Start":"08:10.890 ","End":"08:15.140","Text":"Animals like that also sometimes will not move and they will"},{"Start":"08:15.140 ","End":"08:22.080","Text":"lower their body temperatures by reducing their activity."}],"ID":28002},{"Watched":false,"Name":"Exoskeleton","Duration":"3m 58s","ChapterTopicVideoID":26909,"CourseChapterTopicPlaylistID":261502,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.205","Text":"In this video, we\u0027re getting back to animal form and function"},{"Start":"00:05.205 ","End":"00:10.950","Text":"and we\u0027re going to talk about the limits on animal size and shape."},{"Start":"00:10.950 ","End":"00:13.755","Text":"We discussed in the previous video,"},{"Start":"00:13.755 ","End":"00:16.185","Text":"the drag of the water."},{"Start":"00:16.185 ","End":"00:19.305","Text":"When animals move through the water,"},{"Start":"00:19.305 ","End":"00:22.230","Text":"there is drag that they must overcome."},{"Start":"00:22.230 ","End":"00:26.280","Text":"Aquatic organisms are constrained by this drag."},{"Start":"00:26.280 ","End":"00:29.940","Text":"On the other hand, land animals don\u0027t have"},{"Start":"00:29.940 ","End":"00:34.185","Text":"this drag and they are constrained by something else."},{"Start":"00:34.185 ","End":"00:37.278","Text":"They are constrained mainly by gravity"},{"Start":"00:37.278 ","End":"00:41.510","Text":"because gravity is pulling them down and in order to move,"},{"Start":"00:41.510 ","End":"00:44.390","Text":"they have to be able to fight the gravity."},{"Start":"00:44.390 ","End":"00:49.205","Text":"We can see here that different organisms like say the cheetah,"},{"Start":"00:49.205 ","End":"00:51.110","Text":"quarter horse and so on,"},{"Start":"00:51.110 ","End":"00:54.695","Text":"they all move at tremendously different speeds."},{"Start":"00:54.695 ","End":"00:57.845","Text":"Yes, that you can see on the right of this picture,"},{"Start":"00:57.845 ","End":"01:04.175","Text":"but they all have to deal with that gravity. How did they do that?"},{"Start":"01:04.175 ","End":"01:07.130","Text":"Well, first of all, they need to support themselves."},{"Start":"01:07.130 ","End":"01:10.430","Text":"Yes, and that support is going to require an X,"},{"Start":"01:10.430 ","End":"01:12.740","Text":"some form of skeleton."},{"Start":"01:12.740 ","End":"01:16.255","Text":"It can be either an exoskeleton,"},{"Start":"01:16.255 ","End":"01:18.320","Text":"which we\u0027re going to consider first,"},{"Start":"01:18.320 ","End":"01:22.135","Text":"or it can be an endoskeleton."},{"Start":"01:22.135 ","End":"01:25.145","Text":"Let\u0027s first look at the exoskeleton."},{"Start":"01:25.145 ","End":"01:26.750","Text":"In that case, the skeleton,"},{"Start":"01:26.750 ","End":"01:29.990","Text":"the hard part of the animal is going to be on"},{"Start":"01:29.990 ","End":"01:34.250","Text":"the outside and outside of the animal as you can see here,"},{"Start":"01:34.250 ","End":"01:35.935","Text":"let`s say in these barnacles."},{"Start":"01:35.935 ","End":"01:38.323","Text":"What happens there,"},{"Start":"01:38.323 ","End":"01:42.560","Text":"you have a hard exterior which"},{"Start":"01:42.560 ","End":"01:46.819","Text":"may be made of something called chitin and it\u0027s sometimes mineralized."},{"Start":"01:46.819 ","End":"01:48.710","Text":"It has minerals in it that are,"},{"Start":"01:48.710 ","End":"01:51.954","Text":"for instance, made of calcium carbonate."},{"Start":"01:51.954 ","End":"01:55.400","Text":"There are various animals like arthropods,"},{"Start":"01:55.400 ","End":"01:56.900","Text":"crabs and things like that,"},{"Start":"01:56.900 ","End":"01:59.750","Text":"centipedes, crustaceans, other kinds of animals like this"},{"Start":"01:59.750 ","End":"02:02.450","Text":"that have this external skeleton."},{"Start":"02:02.450 ","End":"02:05.810","Text":"It has some advantages because first of all,"},{"Start":"02:05.810 ","End":"02:09.305","Text":"it certainly provides physical support to the body."},{"Start":"02:09.305 ","End":"02:14.555","Text":"It protects the inner organs because it\u0027s hard on the outside."},{"Start":"02:14.555 ","End":"02:17.400","Text":"It certainly protects against water loss,"},{"Start":"02:17.400 ","End":"02:18.960","Text":"and for land animals,"},{"Start":"02:18.960 ","End":"02:23.850","Text":"that\u0027s a problem because if the water evaporates from the animal too quickly,"},{"Start":"02:23.850 ","End":"02:26.210","Text":"will dry up and not be able to function."},{"Start":"02:26.210 ","End":"02:28.970","Text":"Of course, all animals need water."},{"Start":"02:28.970 ","End":"02:30.395","Text":"But in addition to that,"},{"Start":"02:30.395 ","End":"02:34.940","Text":"it also provides attachment surfaces for muscles,"},{"Start":"02:34.940 ","End":"02:37.630","Text":"that\u0027s these ovals over here."},{"Start":"02:37.630 ","End":"02:40.805","Text":"This claw, in the case of this crab,"},{"Start":"02:40.805 ","End":"02:45.140","Text":"has muscles that move this piece"},{"Start":"02:45.140 ","End":"02:49.610","Text":"of the claw up and down and of course those muscles have to be attached to something."},{"Start":"02:49.610 ","End":"02:54.860","Text":"They\u0027re attached to this exterior skeleton."},{"Start":"02:54.860 ","End":"02:59.980","Text":"But of course, there are disadvantages of an exoskeleton."},{"Start":"02:59.980 ","End":"03:06.005","Text":"For instance, the animal can\u0027t grow if the outside is hard."},{"Start":"03:06.005 ","End":"03:11.195","Text":"It limits the ability of the animal to grow continually."},{"Start":"03:11.195 ","End":"03:14.360","Text":"You can see in this molt, for instance,"},{"Start":"03:14.360 ","End":"03:20.594","Text":"so this was the exoskeleton of this grasshopper."},{"Start":"03:20.594 ","End":"03:25.040","Text":"What happened was that in order for the grasshopper to keep growing,"},{"Start":"03:25.040 ","End":"03:29.645","Text":"what it had to do was get out of it`s exoskeleton and make a new one,"},{"Start":"03:29.645 ","End":"03:31.894","Text":"that was called molting."},{"Start":"03:31.894 ","End":"03:34.550","Text":"If that doesn\u0027t happen at the proper time,"},{"Start":"03:34.550 ","End":"03:38.420","Text":"then there may be a problem surety of the animal."},{"Start":"03:38.420 ","End":"03:43.640","Text":"Furthermore, as the animal gets bigger and heavier, of course,"},{"Start":"03:43.640 ","End":"03:49.438","Text":"this external skeleton must get heavier as well and harder to be in."},{"Start":"03:49.438 ","End":"03:55.295","Text":"Therefore thicker so that it can support the internal weight,"},{"Start":"03:55.295 ","End":"03:59.159","Text":"it\u0027s inside of the organism."}],"ID":28003}],"Thumbnail":null,"ID":261502},{"Name":"Animal Primary Tissues","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"The Basis for Connective tissues","Duration":"5m 37s","ChapterTopicVideoID":26393,"CourseChapterTopicPlaylistID":255406,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.330","Text":"Welcome back. In this part of the course,"},{"Start":"00:03.330 ","End":"00:06.030","Text":"we\u0027re going to be discussing tissues."},{"Start":"00:06.030 ","End":"00:08.640","Text":"I think you have a feel for what tissues are."},{"Start":"00:08.640 ","End":"00:17.070","Text":"Tissues are an integrated group of cells that share a common structure,"},{"Start":"00:17.070 ","End":"00:19.395","Text":"and a common function."},{"Start":"00:19.395 ","End":"00:23.390","Text":"For example, you could have your liver would be a tissue,"},{"Start":"00:23.390 ","End":"00:25.510","Text":"your skin is a tissue,"},{"Start":"00:25.510 ","End":"00:27.670","Text":"let\u0027s say muscle is a tissue."},{"Start":"00:27.670 ","End":"00:31.520","Text":"These are various tissues and they have a common function."},{"Start":"00:31.520 ","End":"00:36.410","Text":"Each of them is made up of different groups of cells."},{"Start":"00:36.410 ","End":"00:41.090","Text":"Let\u0027s look at different kinds of tissues"},{"Start":"00:41.090 ","End":"00:47.270","Text":"and we\u0027ll start with talking about the following tissues."},{"Start":"00:47.270 ","End":"00:50.360","Text":"Let\u0027s start with connective tissues."},{"Start":"00:50.360 ","End":"00:55.370","Text":"Connective tissues are going to connect other tissues together,"},{"Start":"00:55.370 ","End":"01:00.020","Text":"to hold them together in order to provide support."},{"Start":"01:00.020 ","End":"01:04.250","Text":"But then there are other tissues the connective tissue could hold together,"},{"Start":"01:04.250 ","End":"01:10.850","Text":"say the epithelium that lines the various cavities like let\u0027s say our intestine,"},{"Start":"01:10.850 ","End":"01:14.029","Text":"that\u0027s the cells that are on the inside of the intestine."},{"Start":"01:14.029 ","End":"01:16.370","Text":"They could be lining open spaces like say,"},{"Start":"01:16.370 ","End":"01:19.580","Text":"the inside of our mouth and various surfaces"},{"Start":"01:19.580 ","End":"01:23.330","Text":"like even our skin would be epithelial tissue."},{"Start":"01:23.330 ","End":"01:25.895","Text":"It\u0027s a particular tissue."},{"Start":"01:25.895 ","End":"01:29.225","Text":"Next one we might want to talk about is muscle."},{"Start":"01:29.225 ","End":"01:32.840","Text":"Muscle is a separate tissue that you can relate to"},{"Start":"01:32.840 ","End":"01:36.545","Text":"quite well and that helps generate movement, of course,"},{"Start":"01:36.545 ","End":"01:41.435","Text":"and another tissue would be the nervous tissue,"},{"Start":"01:41.435 ","End":"01:47.390","Text":"which will make up the nervous system and they generate electrical signals."},{"Start":"01:47.390 ","End":"01:50.195","Text":"Now if we look at each of these tissues, of course,"},{"Start":"01:50.195 ","End":"01:54.725","Text":"they will look very much different one from the other."},{"Start":"01:54.725 ","End":"01:56.929","Text":"If we look at them underneath the microscope,"},{"Start":"01:56.929 ","End":"02:00.710","Text":"they\u0027re quite different from each other and they have different kinds of cells"},{"Start":"02:00.710 ","End":"02:04.775","Text":"in them that do different jobs."},{"Start":"02:04.775 ","End":"02:09.890","Text":"Let\u0027s start out by looking at connective tissues."},{"Start":"02:09.890 ","End":"02:12.380","Text":"They are used, as we had said,"},{"Start":"02:12.380 ","End":"02:17.979","Text":"mainly to connect different tissues together and to give the body structure"},{"Start":"02:17.979 ","End":"02:24.530","Text":"and they will consist of basically 2 different things."},{"Start":"02:24.530 ","End":"02:30.125","Text":"They will consist of cells and a non-cellular matrix,"},{"Start":"02:30.125 ","End":"02:31.760","Text":"so we have both cells,"},{"Start":"02:31.760 ","End":"02:33.770","Text":"many of them are called fibroblasts,"},{"Start":"02:33.770 ","End":"02:37.610","Text":"as we\u0027ll see and a different material,"},{"Start":"02:37.610 ","End":"02:40.580","Text":"not cells outside of cells,"},{"Start":"02:40.580 ","End":"02:45.260","Text":"forming something called a matrix."},{"Start":"02:45.260 ","End":"02:54.960","Text":"The matrix is usually composed of both fibers and a jelly-like solid foundation,"},{"Start":"02:54.960 ","End":"03:00.460","Text":"so they\u0027re these fibers in this liquid jelly-like foundation."},{"Start":"03:00.460 ","End":"03:07.295","Text":"This foundation or this ground substance usually contains some combination of"},{"Start":"03:07.295 ","End":"03:13.855","Text":"fibers that are made of different proteins called collagen or elastic fibers,"},{"Start":"03:13.855 ","End":"03:16.820","Text":"or you\u0027ll see it\u0027s made up of something called elastin,"},{"Start":"03:16.820 ","End":"03:19.415","Text":"or these other fibers called reticular fibers"},{"Start":"03:19.415 ","End":"03:22.730","Text":"and we\u0027ll go more into depth about what they are."},{"Start":"03:22.730 ","End":"03:24.424","Text":"The cellular portion,"},{"Start":"03:24.424 ","End":"03:25.880","Text":"so the cells,"},{"Start":"03:25.880 ","End":"03:28.850","Text":"have primarily 2 different kinds of cells."},{"Start":"03:28.850 ","End":"03:30.740","Text":"They have fibroblasts in them."},{"Start":"03:30.740 ","End":"03:34.790","Text":"These are cells that secrete these various proteins that are in"},{"Start":"03:34.790 ","End":"03:39.200","Text":"this extracellular space and macrophages."},{"Start":"03:39.200 ","End":"03:43.310","Text":"Macrophages are going to be involved in the immune system so in case there"},{"Start":"03:43.310 ","End":"03:47.915","Text":"are bacteria or other invaders that invade this system,"},{"Start":"03:47.915 ","End":"03:49.580","Text":"they can be fought."},{"Start":"03:49.580 ","End":"03:51.230","Text":"You\u0027ll see there are other cells as well."},{"Start":"03:51.230 ","End":"03:55.909","Text":"For instance, there are mast cells here that are also in lymphocytes,"},{"Start":"03:55.909 ","End":"04:01.370","Text":"that are also involved in the immune system and there can also be blood vessels,"},{"Start":"04:01.370 ","End":"04:03.230","Text":"small blood vessels, capillaries,"},{"Start":"04:03.230 ","End":"04:06.805","Text":"which go through this region."},{"Start":"04:06.805 ","End":"04:12.000","Text":"Now let\u0027s look at these fibers."},{"Start":"04:12.000 ","End":"04:16.275","Text":"Their fibers are made, as we said,"},{"Start":"04:16.275 ","End":"04:18.450","Text":"of 3 different kinds of proteins,"},{"Start":"04:18.450 ","End":"04:20.810","Text":"and the first was called collagen."},{"Start":"04:20.810 ","End":"04:24.365","Text":"Collagen provides the strength to the tissue,"},{"Start":"04:24.365 ","End":"04:26.105","Text":"prevents it from being torn."},{"Start":"04:26.105 ","End":"04:29.060","Text":"It\u0027s very strong this tissue,"},{"Start":"04:29.060 ","End":"04:34.280","Text":"and it may also separate a particular tissue from the surrounding tissues."},{"Start":"04:34.280 ","End":"04:41.555","Text":"We have these strong large collagen fibers."},{"Start":"04:41.555 ","End":"04:43.735","Text":"Next, we have something smaller,"},{"Start":"04:43.735 ","End":"04:52.110","Text":"these elastin fibers or these elastic fibers that are also somewhat flexible and they"},{"Start":"04:52.110 ","End":"04:56.200","Text":"give the tissues some flexibility so it\u0027s both got strength"},{"Start":"04:56.200 ","End":"05:01.255","Text":"from the collagen and elasticity from the elastin."},{"Start":"05:01.255 ","End":"05:03.560","Text":"Finally, there are smaller fibers."},{"Start":"05:03.560 ","End":"05:07.940","Text":"There\u0027s these reticular fibers that"},{"Start":"05:07.940 ","End":"05:13.115","Text":"are holding things together so we can see them over here are these purple lines,"},{"Start":"05:13.115 ","End":"05:14.780","Text":"are these reticular fibers."},{"Start":"05:14.780 ","End":"05:18.260","Text":"They\u0027re fine fibrous fibers that occur in the networks to make up"},{"Start":"05:18.260 ","End":"05:22.925","Text":"the supporting tissue of many of the organs."},{"Start":"05:22.925 ","End":"05:24.874","Text":"In the next videos,"},{"Start":"05:24.874 ","End":"05:29.540","Text":"we\u0027ll discuss the connective tissues in more detail and see how"},{"Start":"05:29.540 ","End":"05:36.989","Text":"these various fibers and cells make up the different tissues."}],"ID":27297},{"Watched":false,"Name":"Connective Tissue Overview","Duration":"6m 30s","ChapterTopicVideoID":26390,"CourseChapterTopicPlaylistID":255406,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.170 ","End":"00:09.075","Text":"Now let\u0027s look at the connective tissues that contain both the fibers and the cells."},{"Start":"00:09.075 ","End":"00:16.740","Text":"There are different types of connective tissues and let\u0027s look at what they\u0027re called."},{"Start":"00:16.740 ","End":"00:20.925","Text":"First of all, we have connective tissue proper,"},{"Start":"00:20.925 ","End":"00:23.213","Text":"specifically connective tissue,"},{"Start":"00:23.213 ","End":"00:28.695","Text":"and we have something called loose or areolar connective tissue,"},{"Start":"00:28.695 ","End":"00:31.245","Text":"and this binds the epithelia,"},{"Start":"00:31.245 ","End":"00:35.365","Text":"remember the things that are on the outside of tissues,"},{"Start":"00:35.365 ","End":"00:40.510","Text":"to the underlying tissues and holds those organs in place."},{"Start":"00:40.510 ","End":"00:44.810","Text":"We have here this loose connective tissue,"},{"Start":"00:44.810 ","End":"00:47.625","Text":"as you can see here on the right,"},{"Start":"00:47.625 ","End":"00:51.960","Text":"and it\u0027s going to hold the underlying tissues, in this case,"},{"Start":"00:51.960 ","End":"00:53.535","Text":"there\u0027s some bone here,"},{"Start":"00:53.535 ","End":"00:57.470","Text":"to the other tissues that are around it."},{"Start":"00:57.470 ","End":"01:01.820","Text":"Then we have dense fibrous connective tissue."},{"Start":"01:01.820 ","End":"01:04.340","Text":"That\u0027s found in things that are called tendons,"},{"Start":"01:04.340 ","End":"01:06.140","Text":"that you probably know about them,"},{"Start":"01:06.140 ","End":"01:09.460","Text":"which attach muscles to bones."},{"Start":"01:09.460 ","End":"01:12.620","Text":"There\u0027s this dense connective tissue and here you can"},{"Start":"01:12.620 ","End":"01:16.015","Text":"see the muscle over here which connects to the bone."},{"Start":"01:16.015 ","End":"01:18.465","Text":"There is this connective tissue here,"},{"Start":"01:18.465 ","End":"01:22.610","Text":"this dense fibrous tissue is found in the tendons, as I said,"},{"Start":"01:22.610 ","End":"01:25.385","Text":"which attach muscles to bones and as well in"},{"Start":"01:25.385 ","End":"01:29.720","Text":"ligaments which connect the bones at the joints."},{"Start":"01:29.720 ","End":"01:33.050","Text":"Sometimes bones are connected to each other and they\u0027re"},{"Start":"01:33.050 ","End":"01:37.295","Text":"connected as well with this dense fibrous material."},{"Start":"01:37.295 ","End":"01:41.255","Text":"In addition to this, we have other special connective tissue."},{"Start":"01:41.255 ","End":"01:44.705","Text":"We do have, for instance, something called cartilage."},{"Start":"01:44.705 ","End":"01:49.655","Text":"Cartilage is very strong and a flexible support material."},{"Start":"01:49.655 ","End":"01:50.930","Text":"You know about cartilage."},{"Start":"01:50.930 ","End":"01:54.080","Text":"Let\u0027s say cartilage it\u0027s in your ear or in your nose."},{"Start":"01:54.080 ","End":"02:01.445","Text":"It\u0027s flexible, but it\u0027s strong and it returns to the same shape if you move it."},{"Start":"02:01.445 ","End":"02:05.395","Text":"Of course, there is also bone."},{"Start":"02:05.395 ","End":"02:07.775","Text":"Bone as we can see over here,"},{"Start":"02:07.775 ","End":"02:08.990","Text":"as opposed to cartilage,"},{"Start":"02:08.990 ","End":"02:12.700","Text":"you see that those are different kinds of tissues."},{"Start":"02:12.700 ","End":"02:14.360","Text":"The bone is mineralized."},{"Start":"02:14.360 ","End":"02:16.435","Text":"It has minerals in it,"},{"Start":"02:16.435 ","End":"02:18.100","Text":"like calcium for instance."},{"Start":"02:18.100 ","End":"02:21.005","Text":"It is not so flexible,"},{"Start":"02:21.005 ","End":"02:26.540","Text":"but it is strong and it forms the skeleton of many organisms."},{"Start":"02:26.540 ","End":"02:30.785","Text":"Of course not all multi cellular organisms are going to have a skeleton,"},{"Start":"02:30.785 ","End":"02:33.815","Text":"certainly not the kind you\u0027re probably thinking about,"},{"Start":"02:33.815 ","End":"02:35.765","Text":"and we\u0027ll get into that a little bit later,"},{"Start":"02:35.765 ","End":"02:40.534","Text":"but larger organisms are going to need a skeleton."},{"Start":"02:40.534 ","End":"02:43.205","Text":"Then there\u0027s adipose tissue."},{"Start":"02:43.205 ","End":"02:50.000","Text":"Adipose tissue, which stores fat for insulation and fuel. That looks different."},{"Start":"02:50.000 ","End":"02:52.820","Text":"Here you can see the fat globules that are inside each of"},{"Start":"02:52.820 ","End":"02:56.210","Text":"these cells and that will be here in this picture of an arm,"},{"Start":"02:56.210 ","End":"03:03.270","Text":"they \u0027ll be outside the muscle and that\u0027s going to store both fat for fuel,"},{"Start":"03:03.270 ","End":"03:09.830","Text":"that can really be burned later and it can also be served as insulation."},{"Start":"03:09.830 ","End":"03:12.770","Text":"Finally, you may not think of this as a tissue,"},{"Start":"03:12.770 ","End":"03:14.600","Text":"but it certainly is, blood."},{"Start":"03:14.600 ","End":"03:19.265","Text":"Well, blood is composed of cells and then there\u0027s the material around it."},{"Start":"03:19.265 ","End":"03:25.080","Text":"Blood cells and then there are cell fragments in the blood plasma."},{"Start":"03:25.080 ","End":"03:26.550","Text":"Here we see that blood contains"},{"Start":"03:26.550 ","End":"03:29.940","Text":"different kinds of cells and different kinds of materials,"},{"Start":"03:29.940 ","End":"03:34.945","Text":"it\u0027s also a tissue and it just happens to be more liquidy."},{"Start":"03:34.945 ","End":"03:41.060","Text":"Now let\u0027s look at the loose or the areolar connective tissue in more detail."},{"Start":"03:41.060 ","End":"03:45.770","Text":"It\u0027s most widely distributed of all the connective tissues."},{"Start":"03:45.770 ","End":"03:47.105","Text":"There\u0027s a lot of it."},{"Start":"03:47.105 ","End":"03:48.650","Text":"You might not think about it a lot,"},{"Start":"03:48.650 ","End":"03:51.295","Text":"but it\u0027s all over the place."},{"Start":"03:51.295 ","End":"03:55.220","Text":"It consists of a loose irregular network of these proteins,"},{"Start":"03:55.220 ","End":"03:57.575","Text":"elastin and collagen, as we mentioned earlier."},{"Start":"03:57.575 ","End":"04:01.130","Text":"They are suspended within a relatively large amount of"},{"Start":"04:01.130 ","End":"04:05.240","Text":"this ground liquidy, jelly-like substance."},{"Start":"04:05.240 ","End":"04:07.745","Text":"Here\u0027s a picture that you can see."},{"Start":"04:07.745 ","End":"04:13.580","Text":"That\u0027s a microscope slide that shows actual cells that are inside"},{"Start":"04:13.580 ","End":"04:20.770","Text":"this matrix that contains both the collagen and the elastin fibers."},{"Start":"04:20.770 ","End":"04:25.610","Text":"It joins the cells of major tissues like muscle,"},{"Start":"04:25.610 ","End":"04:26.810","Text":"nerve, epithelia,"},{"Start":"04:26.810 ","End":"04:30.169","Text":"and then connects the various tissues to make organs."},{"Start":"04:30.169 ","End":"04:32.195","Text":"If we didn\u0027t have this connective tissue,"},{"Start":"04:32.195 ","End":"04:35.855","Text":"everything would just be 1 big mushy mess."},{"Start":"04:35.855 ","End":"04:37.910","Text":"Of course that would not be any good."},{"Start":"04:37.910 ","End":"04:39.500","Text":"It is also found, of course,"},{"Start":"04:39.500 ","End":"04:44.390","Text":"around every blood vessel and between most body organs."},{"Start":"04:44.390 ","End":"04:49.295","Text":"Next, let\u0027s look at the fibrous connective tissue."},{"Start":"04:49.295 ","End":"04:55.250","Text":"It contains large amounts of collagen fibers and a few cells,"},{"Start":"04:55.250 ","End":"04:56.810","Text":"the cells in the matrix materials."},{"Start":"04:56.810 ","End":"04:59.630","Text":"You can see this looks quite different from what we saw before."},{"Start":"04:59.630 ","End":"05:06.980","Text":"It contains some fibroblasts and lots of fiber because this is going to be much stronger."},{"Start":"05:06.980 ","End":"05:10.430","Text":"These irregularly fibrous connective tissues are"},{"Start":"05:10.430 ","End":"05:14.140","Text":"found in areas of the body where stress occurs from all directions."},{"Start":"05:14.140 ","End":"05:15.830","Text":"For instance, the dermis of the skin."},{"Start":"05:15.830 ","End":"05:21.890","Text":"It can be pulled in every direction and that\u0027s going to have to be very strong."},{"Start":"05:21.890 ","End":"05:27.200","Text":"In addition, we have very regular connective tissue,"},{"Start":"05:27.200 ","End":"05:30.530","Text":"in other words, not irregular like we just mentioned earlier,"},{"Start":"05:30.530 ","End":"05:31.610","Text":"but we have regular."},{"Start":"05:31.610 ","End":"05:33.470","Text":"In other words, everything\u0027s in the same direction,"},{"Start":"05:33.470 ","End":"05:37.595","Text":"more like the picture that you have in front of you here and"},{"Start":"05:37.595 ","End":"05:42.005","Text":"it will be found more in tendons and in ligaments."},{"Start":"05:42.005 ","End":"05:44.275","Text":"Next, we have cartilage."},{"Start":"05:44.275 ","End":"05:48.020","Text":"Cartilage is strong and flexible support material."},{"Start":"05:48.020 ","End":"05:54.260","Text":"The tissue has a large amount of matrix and some fibers in it."},{"Start":"05:54.260 ","End":"05:59.855","Text":"It\u0027s softer than the other kind of tissue that we were talking about before."},{"Start":"05:59.855 ","End":"06:05.180","Text":"As you can see, it has in its cells that are called chondrocytes,"},{"Start":"06:05.180 ","End":"06:07.655","Text":"you can see them in the pictures over here."},{"Start":"06:07.655 ","End":"06:11.645","Text":"These chondrocytes are found in what are called lacunae."},{"Start":"06:11.645 ","End":"06:17.375","Text":"Lacunae they\u0027re little holes that are inside the matrix"},{"Start":"06:17.375 ","End":"06:23.675","Text":"and make the matrix together with the various fibers that are in the tissue."},{"Start":"06:23.675 ","End":"06:25.280","Text":"In the next video,"},{"Start":"06:25.280 ","End":"06:30.600","Text":"we\u0027ll continue discussing different cartilage types."}],"ID":27298},{"Watched":false,"Name":"Cartilage and Bone","Duration":"8m 52s","ChapterTopicVideoID":26391,"CourseChapterTopicPlaylistID":255406,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.020","Text":"Now, let\u0027s go back and discuss cartilage."},{"Start":"00:04.020 ","End":"00:06.990","Text":"There are different cartilage types."},{"Start":"00:06.990 ","End":"00:10.170","Text":"Let\u0027s start with elastic cartilage."},{"Start":"00:10.170 ","End":"00:15.315","Text":"This is going to be cartilage that contains a large amount of elastic fibers"},{"Start":"00:15.315 ","End":"00:20.940","Text":"and therefore is going to have very high flexibility and examples of this,"},{"Start":"00:20.940 ","End":"00:25.545","Text":"for instance, are in most of the ear and the most vertebrates."},{"Start":"00:25.545 ","End":"00:27.810","Text":"It\u0027s very flexible, you can move it around,"},{"Start":"00:27.810 ","End":"00:29.220","Text":"but as we said before,"},{"Start":"00:29.220 ","End":"00:33.315","Text":"it goes back to its old shape if you leave it alone,"},{"Start":"00:33.315 ","End":"00:35.580","Text":"and also portions of the larynx."},{"Start":"00:35.580 ","End":"00:37.755","Text":"The larynx is in your throat,"},{"Start":"00:37.755 ","End":"00:39.690","Text":"and if you push on that,"},{"Start":"00:39.690 ","End":"00:42.190","Text":"you can feel that it\u0027s movable."},{"Start":"00:42.190 ","End":"00:43.880","Text":"But of course,"},{"Start":"00:43.880 ","End":"00:45.170","Text":"it maintains a shape."},{"Start":"00:45.170 ","End":"00:48.530","Text":"Fibrocartilage are supposed to be elastic cartilage that"},{"Start":"00:48.530 ","End":"00:52.350","Text":"contains a large amount of collagen fibers."},{"Start":"00:52.350 ","End":"00:55.760","Text":"Now, remember the elastic fibers are more elastic."},{"Start":"00:55.760 ","End":"00:57.260","Text":"It has elastin in it."},{"Start":"00:57.260 ","End":"01:05.610","Text":"Collagen is less elastic and therefore has very high strength and you know about them."},{"Start":"01:05.610 ","End":"01:10.550","Text":"For instance, the disks that are in your back between the vertebra,"},{"Start":"01:10.550 ","End":"01:15.715","Text":"intervertebral discs that are in animals."},{"Start":"01:15.715 ","End":"01:18.125","Text":"Here you can see, for instance,"},{"Start":"01:18.125 ","End":"01:23.225","Text":"what it looks like whereas the elastic cartilage didn\u0027t have so much of a structure,"},{"Start":"01:23.225 ","End":"01:25.190","Text":"the cells within the fibers."},{"Start":"01:25.190 ","End":"01:29.510","Text":"The fibrocartilage has more of a structure,"},{"Start":"01:29.510 ","End":"01:33.005","Text":"more regular, it looks a little bit more like muscle."},{"Start":"01:33.005 ","End":"01:36.830","Text":"Then finally, we have hyaline cartilage,"},{"Start":"01:36.830 ","End":"01:42.920","Text":"and that contains a considerable amount of collagen and it has a very firm consistency."},{"Start":"01:42.920 ","End":"01:47.795","Text":"Where do we find that? We find that in movable joints such as the knee and the shoulder,"},{"Start":"01:47.795 ","End":"01:50.330","Text":"ribs, nose, the larynx and trachea."},{"Start":"01:50.330 ","End":"01:56.880","Text":"This has to be more flexible and more lubricating."},{"Start":"01:56.880 ","End":"01:59.750","Text":"That\u0027s what we know about cartilage."},{"Start":"01:59.750 ","End":"02:03.785","Text":"Now, if we also have some calcification,"},{"Start":"02:03.785 ","End":"02:06.110","Text":"then we have bone,"},{"Start":"02:06.110 ","End":"02:08.705","Text":"of course, which is forms the skeleton,"},{"Start":"02:08.705 ","End":"02:11.630","Text":"as we can see here and of course,"},{"Start":"02:11.630 ","End":"02:13.430","Text":"different parts of the bone have"},{"Start":"02:13.430 ","End":"02:18.500","Text":"different names and the major functions of the bones are for body support,"},{"Start":"02:18.500 ","End":"02:21.425","Text":"facilitation of movement, protection of internal organs."},{"Start":"02:21.425 ","End":"02:22.790","Text":"Protection of internal organs we have"},{"Start":"02:22.790 ","End":"02:25.445","Text":"the ribcage so that what\u0027s underneath is protected,"},{"Start":"02:25.445 ","End":"02:28.055","Text":"if you get hit or your brain,"},{"Start":"02:28.055 ","End":"02:30.065","Text":"for instance, is protected by the skull."},{"Start":"02:30.065 ","End":"02:31.924","Text":"You have storage of minerals."},{"Start":"02:31.924 ","End":"02:34.220","Text":"There\u0027s also some fat, believe it or not,"},{"Start":"02:34.220 ","End":"02:39.410","Text":"that\u0027s stored inside bones in the bone marrow and it"},{"Start":"02:39.410 ","End":"02:45.485","Text":"also is an organ that makes new blood cells hematopoiesis."},{"Start":"02:45.485 ","End":"02:50.080","Text":"That\u0027s in the bone marrow. We\u0027re going to have new cells made inside the bones,"},{"Start":"02:50.080 ","End":"02:53.565","Text":"so the bones are going to be very important."},{"Start":"02:53.565 ","End":"02:56.040","Text":"What is the bone composed of?"},{"Start":"02:56.040 ","End":"03:00.395","Text":"Well, it\u0027s composed of 2 different types of matrix material."},{"Start":"03:00.395 ","End":"03:03.950","Text":"There are 2 types of material really."},{"Start":"03:03.950 ","End":"03:10.220","Text":"First of all, we have matrix and cells and now looking at the matrix part of it,"},{"Start":"03:10.220 ","End":"03:15.260","Text":"we have both an organic matrix that contains collagen and elastic fibers,"},{"Start":"03:15.260 ","End":"03:16.370","Text":"just as we saw before,"},{"Start":"03:16.370 ","End":"03:19.031","Text":"giving both strength and flexibility,"},{"Start":"03:19.031 ","End":"03:23.150","Text":"but we also have 65 percent of it is made of"},{"Start":"03:23.150 ","End":"03:27.950","Text":"inorganic material like salts and primarily calcium,"},{"Start":"03:27.950 ","End":"03:31.190","Text":"which give it its strong basis."},{"Start":"03:31.190 ","End":"03:34.220","Text":"Here we have an inorganic parts with calcium,"},{"Start":"03:34.220 ","End":"03:36.530","Text":"in this case they\u0027re showing also phosphorus."},{"Start":"03:36.530 ","End":"03:42.455","Text":"Then we have, if there is a deficiency of the organic material,"},{"Start":"03:42.455 ","End":"03:45.065","Text":"yes, the tissue will break."},{"Start":"03:45.065 ","End":"03:50.000","Text":"But if there\u0027s a deficiency of the inorganic material,"},{"Start":"03:50.000 ","End":"03:51.605","Text":"then when stress is put on it,"},{"Start":"03:51.605 ","End":"03:54.979","Text":"the tissue will bend and it\u0027s actually the combination."},{"Start":"03:54.979 ","End":"03:57.770","Text":"You have to have the right ratio between these things to have"},{"Start":"03:57.770 ","End":"04:01.160","Text":"both strength and some flexibility."},{"Start":"04:01.160 ","End":"04:03.830","Text":"You don\u0027t want it break right away."},{"Start":"04:03.830 ","End":"04:06.170","Text":"Now, in addition, of course,"},{"Start":"04:06.170 ","End":"04:09.020","Text":"we have inside the bone,"},{"Start":"04:09.020 ","End":"04:11.165","Text":"we have cells, of course,"},{"Start":"04:11.165 ","End":"04:16.775","Text":"all living things have cells and we have what are called osteogenic cells."},{"Start":"04:16.775 ","End":"04:20.505","Text":"These are cells that divide in the bone and"},{"Start":"04:20.505 ","End":"04:26.050","Text":"let the bone grow and they develop eventually,"},{"Start":"04:26.050 ","End":"04:29.750","Text":"these osteogenic cells develop into the cells it stopped"},{"Start":"04:29.750 ","End":"04:34.510","Text":"dividing that are called osteoblasts that are inside the cell."},{"Start":"04:34.510 ","End":"04:41.705","Text":"Here are the osteoblasts and they make bone for both growth and remodeling."},{"Start":"04:41.705 ","End":"04:46.430","Text":"Yes, so here\u0027s an osteoblast and it forms tissue."},{"Start":"04:46.430 ","End":"04:49.050","Text":"Then we have osteocytes,"},{"Start":"04:51.040 ","End":"04:54.490","Text":"and they also,"},{"Start":"04:54.490 ","End":"04:56.750","Text":"these are cells that occupy lacuna."},{"Start":"04:56.750 ","End":"05:02.060","Text":"Remember lacuna are these little holes and they\u0027re contained in the calcified matrix."},{"Start":"05:02.060 ","End":"05:05.690","Text":"These are very mature osteoblasts."},{"Start":"05:05.690 ","End":"05:08.030","Text":"Then we have osteoclasts with"},{"Start":"05:08.030 ","End":"05:15.045","Text":"a C osteoclasts and those actually break down bone for remodeling."},{"Start":"05:15.045 ","End":"05:20.329","Text":"Here are the osteoclasts and they function in resorption during destruction."},{"Start":"05:20.329 ","End":"05:23.585","Text":"Now, all tissues remodel all the time."},{"Start":"05:23.585 ","End":"05:28.040","Text":"Otherwise, they would just eventually die and fall apart."},{"Start":"05:28.040 ","End":"05:31.400","Text":"There\u0027s a remodeling, there\u0027s a strengthening of the bone"},{"Start":"05:31.400 ","End":"05:34.925","Text":"and these osteoclasts are responsible for that"},{"Start":"05:34.925 ","End":"05:38.600","Text":"and they have also the access to"},{"Start":"05:38.600 ","End":"05:44.240","Text":"the calcium which is stored in the tissues if they\u0027re needed for other things."},{"Start":"05:44.240 ","End":"05:46.655","Text":"Now let\u0027s look at the bone layers."},{"Start":"05:46.655 ","End":"05:51.830","Text":"We have the compact bone that it\u0027s found in the shaft of"},{"Start":"05:51.830 ","End":"05:54.590","Text":"a long bone and the surface of the flat bones and it\u0027s organized"},{"Start":"05:54.590 ","End":"05:58.040","Text":"into various subunits that are called osteons."},{"Start":"05:58.040 ","End":"06:02.030","Text":"These are the various subunits that are found inside the bone."},{"Start":"06:02.030 ","End":"06:07.130","Text":"We have spongy bone in here,"},{"Start":"06:07.130 ","End":"06:09.515","Text":"which is found at the end of a long bone."},{"Start":"06:09.515 ","End":"06:12.830","Text":"You know that if you suck a bone that\u0027s been cooked,"},{"Start":"06:12.830 ","End":"06:16.565","Text":"the inside of it is soft."},{"Start":"06:16.565 ","End":"06:22.070","Text":"That\u0027s the cancellous spongy bone and it\u0027s made of"},{"Start":"06:22.070 ","End":"06:29.180","Text":"these tiny plates that are called trabeculae that are found inside the spongy bone."},{"Start":"06:29.180 ","End":"06:33.815","Text":"Now let\u0027s look at bone structure in even greater detail."},{"Start":"06:33.815 ","End":"06:37.920","Text":"The bone structure, if we look at it in greater detail,"},{"Start":"06:37.920 ","End":"06:42.200","Text":"here we have the bone that has a spongy bone in the compact bone and so now what"},{"Start":"06:42.200 ","End":"06:46.595","Text":"we\u0027ve done is in these 3 different pictures,"},{"Start":"06:46.595 ","End":"06:48.680","Text":"what we do have is a blowup."},{"Start":"06:48.680 ","End":"06:52.940","Text":"First, we have an osteon that we discussed in the previous slide."},{"Start":"06:52.940 ","End":"06:54.935","Text":"Remember the osteons?"},{"Start":"06:54.935 ","End":"07:00.875","Text":"So here we can see an osteon which then is blown up,"},{"Start":"07:00.875 ","End":"07:03.178","Text":"down below over here,"},{"Start":"07:03.178 ","End":"07:07.790","Text":"and here we can see several osteons or these circular structures"},{"Start":"07:07.790 ","End":"07:13.655","Text":"that are contained within the spongy area of the bone."},{"Start":"07:13.655 ","End":"07:17.150","Text":"The basic structure is this osteon,"},{"Start":"07:17.150 ","End":"07:21.859","Text":"not this compact bone and through it there\u0027s a central canal."},{"Start":"07:21.859 ","End":"07:23.330","Text":"You see the hole in the middle?"},{"Start":"07:23.330 ","End":"07:25.925","Text":"There\u0027s central canal in the middle."},{"Start":"07:25.925 ","End":"07:30.185","Text":"Then there are concentric lamellae cells or"},{"Start":"07:30.185 ","End":"07:32.840","Text":"lamellae structures that are connected to each"},{"Start":"07:32.840 ","End":"07:36.565","Text":"other by things that are called canaliculi."},{"Start":"07:36.565 ","End":"07:41.740","Text":"Those are connected to each other by these canaliculi."},{"Start":"07:41.740 ","End":"07:44.215","Text":"Then there are lamellae,"},{"Start":"07:44.215 ","End":"07:50.120","Text":"which are these rings of lacunae with the osteocytes that are in it,"},{"Start":"07:50.120 ","End":"07:52.835","Text":"and through the middle is this canal,"},{"Start":"07:52.835 ","End":"07:58.220","Text":"which is called the Haversian canal and there\u0027s central tubes"},{"Start":"07:58.220 ","End":"08:04.620","Text":"and blood vessels and nerves and whatnot travel through the middle of these."},{"Start":"08:05.000 ","End":"08:13.160","Text":"Here we can see a photograph of a bone structure of the exterior matrix."},{"Start":"08:13.160 ","End":"08:17.805","Text":"Inside of this or here we\u0027re going to have the lacunae."},{"Start":"08:17.805 ","End":"08:24.455","Text":"This large structure here is called the trabecula,"},{"Start":"08:24.455 ","End":"08:29.270","Text":"the basic structure of the spongy bone and there are these tiny plates that service"},{"Start":"08:29.270 ","End":"08:34.970","Text":"struts to give this spongy bone some strength, these various struts."},{"Start":"08:34.970 ","End":"08:41.224","Text":"But over time, these plates can break causing the bone to become less resilient."},{"Start":"08:41.224 ","End":"08:44.375","Text":"That certainly happens in older people."},{"Start":"08:44.375 ","End":"08:45.665","Text":"In the next video,"},{"Start":"08:45.665 ","End":"08:51.540","Text":"we will begin to talk about adipose or fat tissue."}],"ID":27299},{"Watched":false,"Name":"Fat and Blood","Duration":"6m 21s","ChapterTopicVideoID":26392,"CourseChapterTopicPlaylistID":255406,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.380 ","End":"00:05.925","Text":"Next, we will talk about adipose tissue or fat tissue."},{"Start":"00:05.925 ","End":"00:10.610","Text":"The major functions of adipose tissue are for energy,"},{"Start":"00:10.610 ","End":"00:13.825","Text":"for storage of fat for future use,"},{"Start":"00:13.825 ","End":"00:15.780","Text":"to protect vital organs."},{"Start":"00:15.780 ","End":"00:17.730","Text":"We may, for instance,"},{"Start":"00:17.730 ","End":"00:20.330","Text":"have fat in our belly to protect what\u0027s underneath."},{"Start":"00:20.330 ","End":"00:24.120","Text":"To maintain body temperature surfaces insulation, and as we\u0027ll see,"},{"Start":"00:24.120 ","End":"00:30.180","Text":"it also helps in making heat and also in the synthesis of steroid hormones."},{"Start":"00:30.180 ","End":"00:34.290","Text":"There are basically 2 different types of adipose tissues."},{"Start":"00:34.290 ","End":"00:38.509","Text":"There\u0027s white adipose tissue that contains primarily"},{"Start":"00:38.509 ","End":"00:44.135","Text":"a very large liquid single lipid droplets."},{"Start":"00:44.135 ","End":"00:47.120","Text":"This cell we have the droplets as well as"},{"Start":"00:47.120 ","End":"00:51.259","Text":"some of the other things that we normally find in cytoplasm,"},{"Start":"00:51.259 ","End":"00:53.780","Text":"but they\u0027re pushed over to 1 side and this is"},{"Start":"00:53.780 ","End":"00:57.355","Text":"the predominant adipose type in adult humans."},{"Start":"00:57.355 ","End":"01:01.940","Text":"The greatest proportion of this tissue is located in the hypodermis."},{"Start":"01:01.940 ","End":"01:05.045","Text":"That\u0027s the area that\u0027s just under the skin,"},{"Start":"01:05.045 ","End":"01:08.585","Text":"and it\u0027s present in the bone marrow and other tissues as well,"},{"Start":"01:08.585 ","End":"01:12.035","Text":"where it fills in the spaces between the cells."},{"Start":"01:12.035 ","End":"01:15.305","Text":"Now in addition to the white adipose tissue,"},{"Start":"01:15.305 ","End":"01:18.110","Text":"we also have brown adipose tissue."},{"Start":"01:18.110 ","End":"01:19.820","Text":"As you can see,"},{"Start":"01:19.820 ","End":"01:23.420","Text":"it looks a bit different because it contains"},{"Start":"01:23.420 ","End":"01:28.100","Text":"numerous lipid droplets in a much higher end as well,"},{"Start":"01:28.100 ","End":"01:30.395","Text":"a much higher number of mitochondria."},{"Start":"01:30.395 ","End":"01:33.170","Text":"Mitochondria are these little pink things."},{"Start":"01:33.170 ","End":"01:34.670","Text":"There are some, of course,"},{"Start":"01:34.670 ","End":"01:36.260","Text":"in the white adipocytes,"},{"Start":"01:36.260 ","End":"01:37.520","Text":"but in the brown ones,"},{"Start":"01:37.520 ","End":"01:38.720","Text":"there are lots of them."},{"Start":"01:38.720 ","End":"01:41.630","Text":"That is especially useful because as you\u0027ll remember,"},{"Start":"01:41.630 ","End":"01:45.785","Text":"the mitochondria are the power plants of the cell."},{"Start":"01:45.785 ","End":"01:53.120","Text":"They essentially take sugar and make ATP out of it and they also release heat."},{"Start":"01:53.120 ","End":"01:59.750","Text":"This is how cells produce heat to process called thermogenesis."},{"Start":"01:59.750 ","End":"02:01.325","Text":"It\u0027s non-shivering heat."},{"Start":"02:01.325 ","End":"02:03.220","Text":"It\u0027s just production of heat."},{"Start":"02:03.220 ","End":"02:04.880","Text":"They\u0027re especially abundant,"},{"Start":"02:04.880 ","End":"02:07.309","Text":"these cells in newborns and hibernating"},{"Start":"02:07.309 ","End":"02:10.310","Text":"animals where it\u0027s very important to keep the temperature up."},{"Start":"02:10.310 ","End":"02:15.920","Text":"With age, the amount of brown adipose tissue decreases."},{"Start":"02:15.920 ","End":"02:18.500","Text":"We all know that as people age,"},{"Start":"02:18.500 ","End":"02:21.620","Text":"very often they get thinner and that\u0027s what\u0027s"},{"Start":"02:21.620 ","End":"02:25.090","Text":"happening as these adipocytes tend to disappear."},{"Start":"02:25.090 ","End":"02:30.930","Text":"Now let\u0027s look at the next tissue that we discussed and that is blood."},{"Start":"02:30.930 ","End":"02:33.335","Text":"Blood, of course,"},{"Start":"02:33.335 ","End":"02:41.720","Text":"contains both blood cells and it contains the matrix that is the water,"},{"Start":"02:41.720 ","End":"02:43.760","Text":"the liquid, the plasma that\u0027s around it."},{"Start":"02:43.760 ","End":"02:46.040","Text":"Therefore, it\u0027s called connective tissue."},{"Start":"02:46.040 ","End":"02:47.180","Text":"It\u0027s got both of these things,"},{"Start":"02:47.180 ","End":"02:49.505","Text":"cells, and the matrix."},{"Start":"02:49.505 ","End":"02:52.610","Text":"If we look at the blood cell types,"},{"Start":"02:52.610 ","End":"02:54.904","Text":"there are primarily 2 kinds."},{"Start":"02:54.904 ","End":"02:57.020","Text":"They are erythrocytes, the red blood cells,"},{"Start":"02:57.020 ","End":"03:00.680","Text":"and there are leukocytes that are the white blood cells,"},{"Start":"03:00.680 ","End":"03:04.490","Text":"in addition to this matrix that we discussed before."},{"Start":"03:04.490 ","End":"03:08.075","Text":"Now let\u0027s look at the erythrocytes."},{"Start":"03:08.075 ","End":"03:09.890","Text":"Erythrocytes, first of all,"},{"Start":"03:09.890 ","End":"03:11.179","Text":"are not spherical."},{"Start":"03:11.179 ","End":"03:12.730","Text":"They are flattened."},{"Start":"03:12.730 ","End":"03:16.310","Text":"What that does is it allows these cells to have"},{"Start":"03:16.310 ","End":"03:21.920","Text":"a larger surface area than a spherical cell would have."},{"Start":"03:21.920 ","End":"03:26.090","Text":"That\u0027s important because oxygen is going to"},{"Start":"03:26.090 ","End":"03:30.485","Text":"be delivered from these cells into the tissues."},{"Start":"03:30.485 ","End":"03:35.690","Text":"We want to have the ability to have more diffusion through the cells."},{"Start":"03:35.690 ","End":"03:37.850","Text":"The cells, of course,"},{"Start":"03:37.850 ","End":"03:40.400","Text":"carry this oxygen to the tissues."},{"Start":"03:40.400 ","End":"03:45.200","Text":"They do this by being very rich in the protein hemoglobin,"},{"Start":"03:45.200 ","End":"03:49.345","Text":"which binds oxygen and releases it when it needs to."},{"Start":"03:49.345 ","End":"03:54.410","Text":"Each human red blood cell contains huge amounts of hemoglobin,"},{"Start":"03:54.410 ","End":"03:57.905","Text":"about 270 million molecules."},{"Start":"03:57.905 ","End":"04:01.085","Text":"In order to carry so much hemoglobin,"},{"Start":"04:01.085 ","End":"04:05.360","Text":"these cells actually lose"},{"Start":"04:05.360 ","End":"04:11.015","Text":"their nuclei and their mitochondria because they\u0027re just really a sack of hemoglobin,"},{"Start":"04:11.015 ","End":"04:16.100","Text":"so they can carry the oxygen to the external cells,"},{"Start":"04:16.100 ","End":"04:19.025","Text":"and with time they die."},{"Start":"04:19.025 ","End":"04:25.670","Text":"They\u0027ll circulate for about 100-120 days before being destroyed."},{"Start":"04:25.670 ","End":"04:27.680","Text":"Now in addition to erythrocytes,"},{"Start":"04:27.680 ","End":"04:30.065","Text":"we said that there are these leukocytes."},{"Start":"04:30.065 ","End":"04:36.070","Text":"The leukocytes actually are made up of different kinds of cells."},{"Start":"04:36.070 ","End":"04:40.520","Text":"They are the predominant white blood cell types that are found in the peripheral blood."},{"Start":"04:40.520 ","End":"04:47.525","Text":"They function primarily in the immune response to foreign antigens or various materials."},{"Start":"04:47.525 ","End":"04:49.940","Text":"The different types are leukocytes,"},{"Start":"04:49.940 ","End":"04:54.185","Text":"monocytes, eosinophils and basophils, and neutrophils."},{"Start":"04:54.185 ","End":"04:57.185","Text":"Each of them has a somewhat different function."},{"Start":"04:57.185 ","End":"05:03.110","Text":"The lymphocytes produce antibodies that are tailored to the various foreign antigens."},{"Start":"05:03.110 ","End":"05:07.955","Text":"The monocytes give rise to phagocytic macrophages."},{"Start":"05:07.955 ","End":"05:11.180","Text":"These are cells that will engulf and clean"},{"Start":"05:11.180 ","End":"05:14.360","Text":"up dead and damaged cells and digest those pieces."},{"Start":"05:14.360 ","End":"05:18.465","Text":"They\u0027re clean up cells."},{"Start":"05:18.465 ","End":"05:21.650","Text":"The eosinophils and basophils and they are"},{"Start":"05:21.650 ","End":"05:25.340","Text":"very important for causing the inflammatory response."},{"Start":"05:25.340 ","End":"05:27.140","Text":"Finally, there are the neutrophils,"},{"Start":"05:27.140 ","End":"05:31.385","Text":"which are cells that are also phagocytic,"},{"Start":"05:31.385 ","End":"05:34.954","Text":"and they will engulf things like bacteria."},{"Start":"05:34.954 ","End":"05:38.420","Text":"Finally, in addition to these various cells,"},{"Start":"05:38.420 ","End":"05:42.770","Text":"we have other things in the blood that are not"},{"Start":"05:42.770 ","End":"05:47.555","Text":"necessarily cells like platelets, so thrombocytes."},{"Start":"05:47.555 ","End":"05:52.400","Text":"They\u0027re not cells, but they\u0027re fragments of cytoplasm that are derived from cells."},{"Start":"05:52.400 ","End":"05:57.560","Text":"They undergo a very complicated series of reactions to"},{"Start":"05:57.560 ","End":"06:02.765","Text":"stop damage in the walls of blood vessels."},{"Start":"06:02.765 ","End":"06:04.550","Text":"In other words, they will cause"},{"Start":"06:04.550 ","End":"06:09.290","Text":"blood clots in a way that we\u0027re not going to discuss in detail here."},{"Start":"06:09.290 ","End":"06:15.590","Text":"But they participate in the various stages that lead up to the coagulation of the blood."},{"Start":"06:15.590 ","End":"06:21.870","Text":"Of course, that stops the bleeding through damaged blood vessels."}],"ID":27300},{"Watched":false,"Name":"Epithelial tissue","Duration":"7m 24s","ChapterTopicVideoID":26394,"CourseChapterTopicPlaylistID":255406,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.540 ","End":"00:04.870","Text":"Welcome back to the discussion of basic tissues,"},{"Start":"00:04.870 ","End":"00:09.799","Text":"and in this video we\u0027ll discuss epithelial tissues."},{"Start":"00:10.140 ","End":"00:16.435","Text":"Now, the epithelial tissues cover the outside of organs and the cavity,"},{"Start":"00:16.435 ","End":"00:19.030","Text":"structures that are in the body."},{"Start":"00:19.030 ","End":"00:21.215","Text":"The various cavities."},{"Start":"00:21.215 ","End":"00:26.400","Text":"They\u0027re covering various organisms, these are covers."},{"Start":"00:26.400 ","End":"00:29.515","Text":"Let\u0027s see if we can understand this a bit better."},{"Start":"00:29.515 ","End":"00:33.610","Text":"First of all, these epithelial tissues"},{"Start":"00:33.610 ","End":"00:37.975","Text":"contains cells that are very closely joined together."},{"Start":"00:37.975 ","End":"00:44.150","Text":"There\u0027s very little space between each of these cells because they serve as a cover."},{"Start":"00:44.150 ","End":"00:48.820","Text":"They are designed to keep things from moving,"},{"Start":"00:48.820 ","End":"00:52.460","Text":"that\u0027s liquid, say, water"},{"Start":"00:52.460 ","End":"00:57.965","Text":"or other materials from the inside to the outside or the outside to the inside."},{"Start":"00:57.965 ","End":"01:00.470","Text":"The cells are closely joined together."},{"Start":"01:00.470 ","End":"01:03.830","Text":"They do not contain blood vessels and they receive"},{"Start":"01:03.830 ","End":"01:09.215","Text":"their own nourishment via diffusion from the underlying connective tissue."},{"Start":"01:09.215 ","End":"01:11.915","Text":"The different types of epithelial tissues,"},{"Start":"01:11.915 ","End":"01:14.630","Text":"we said, are classified by the number of layers."},{"Start":"01:14.630 ","End":"01:20.355","Text":"We have a simple epithelium which is composed of a single layer of cells."},{"Start":"01:20.355 ","End":"01:26.150","Text":"You can see the first line here has 1 simple line of cells."},{"Start":"01:26.150 ","End":"01:28.700","Text":"There can be stratified epithelium,"},{"Start":"01:28.700 ","End":"01:30.390","Text":"which is composed of multiple layers,"},{"Start":"01:30.390 ","End":"01:34.070","Text":"so here you can see this cell has multiple layers."},{"Start":"01:34.070 ","End":"01:35.525","Text":"If we\u0027re counting from the bottom,"},{"Start":"01:35.525 ","End":"01:36.710","Text":"here there are 2 layers,"},{"Start":"01:36.710 ","End":"01:39.605","Text":"here there are also 2 layers regardless of the shape of the cell."},{"Start":"01:39.605 ","End":"01:42.395","Text":"There can be something that\u0027s called pseudostratified."},{"Start":"01:42.395 ","End":"01:47.885","Text":"That\u0027s really a single layer of cells like we have down here,"},{"Start":"01:47.885 ","End":"01:53.495","Text":"but the cells themselves can be of varying lengths."},{"Start":"01:53.495 ","End":"01:55.880","Text":"Now let\u0027s look at the shapes of the cells."},{"Start":"01:55.880 ","End":"01:57.830","Text":"They can be cuboidal,"},{"Start":"01:57.830 ","End":"02:00.275","Text":"as we said, that it\u0027s like dice like cubes."},{"Start":"02:00.275 ","End":"02:02.824","Text":"They can be more like columns, columnar,"},{"Start":"02:02.824 ","End":"02:05.420","Text":"say like bricks that are on end,"},{"Start":"02:05.420 ","End":"02:07.150","Text":"we can see that over here."},{"Start":"02:07.150 ","End":"02:09.190","Text":"Or they can be squamous,"},{"Start":"02:09.190 ","End":"02:10.620","Text":"more like floor tiles,"},{"Start":"02:10.620 ","End":"02:13.060","Text":"what we see here on the left."},{"Start":"02:13.060 ","End":"02:17.115","Text":"Now each of these different tissues,"},{"Start":"02:17.115 ","End":"02:21.580","Text":"each of these classes of epithelial tissues are found in"},{"Start":"02:21.580 ","End":"02:27.985","Text":"different locations and they can be described differently as we just said."},{"Start":"02:27.985 ","End":"02:31.390","Text":"The squamous, for instance, are flat, irregular,"},{"Start":"02:31.390 ","End":"02:34.555","Text":"round shape, and they can be found in,"},{"Start":"02:34.555 ","End":"02:36.460","Text":"say, the lungs in the alveoli."},{"Start":"02:36.460 ","End":"02:41.110","Text":"That\u0027s where the oxygen and carbon dioxide pass from"},{"Start":"02:41.110 ","End":"02:46.510","Text":"the blood into the air and the capillaries and skin, mouth, vagina."},{"Start":"02:46.510 ","End":"02:51.870","Text":"The cuboidal cells are found more in the glands or renal tubes,"},{"Start":"02:51.870 ","End":"02:53.005","Text":"we\u0027ll see that in a minute."},{"Start":"02:53.005 ","End":"02:55.299","Text":"The columnar ones more like columns,"},{"Start":"02:55.299 ","End":"02:58.900","Text":"the tall ones are found more in the the digestive tract,"},{"Start":"02:58.900 ","End":"03:00.210","Text":"we\u0027ll see an examples of that,"},{"Start":"03:00.210 ","End":"03:03.382","Text":"and sometimes the flatter cells,"},{"Start":"03:03.382 ","End":"03:08.770","Text":"the transitional ones also can be found in places like the urinary bladder."},{"Start":"03:08.770 ","End":"03:11.680","Text":"Let\u0027s look first at the squamous epithelium,"},{"Start":"03:11.680 ","End":"03:15.375","Text":"the ones that are more flat and round."},{"Start":"03:15.375 ","End":"03:18.325","Text":"They have a centrally located nucleus,"},{"Start":"03:18.325 ","End":"03:24.720","Text":"and the cells fit together to cover some covering or aligning, it\u0027s more flat."},{"Start":"03:24.720 ","End":"03:26.140","Text":"In a single layer,"},{"Start":"03:26.140 ","End":"03:30.565","Text":"they facilitate diffusion into tissues and out of tissues."},{"Start":"03:30.565 ","End":"03:34.685","Text":"For instance, in the lungs or through the capillaries."},{"Start":"03:34.685 ","End":"03:38.630","Text":"In addition, the stratified squamous is the equilibrium"},{"Start":"03:38.630 ","End":"03:42.455","Text":"that has multiple cells one on top of the other,"},{"Start":"03:42.455 ","End":"03:43.850","Text":"occurs in the skin,"},{"Start":"03:43.850 ","End":"03:45.680","Text":"which has to be much stronger of course,"},{"Start":"03:45.680 ","End":"03:52.620","Text":"and it doesn\u0027t necessarily have to be permeable to save water or oxygen,"},{"Start":"03:52.620 ","End":"03:56.705","Text":"and in the tissues that are aligning the mouth and the vagina."},{"Start":"03:56.705 ","End":"03:58.670","Text":"What we see here in this picture is"},{"Start":"03:58.670 ","End":"04:04.010","Text":"the epithelial lining of the surface of the epiglottis,"},{"Start":"04:04.010 ","End":"04:06.140","Text":"that\u0027s something in the back of our mouth."},{"Start":"04:06.140 ","End":"04:12.710","Text":"You can see there are different forms of the stratified squamous epithelium here."},{"Start":"04:12.710 ","End":"04:15.785","Text":"Next, we have the cuboidal epithelium."},{"Start":"04:15.785 ","End":"04:17.600","Text":"Here are the cells, as we\u0027ve mentioned,"},{"Start":"04:17.600 ","End":"04:22.910","Text":"are cube-shaped and they have a single central nucleus."},{"Start":"04:22.910 ","End":"04:27.065","Text":"In addition, they are commonly found in a single layer,"},{"Start":"04:27.065 ","End":"04:29.830","Text":"which is in the glandular tissue."},{"Start":"04:29.830 ","End":"04:31.535","Text":"These are glands, for instance,"},{"Start":"04:31.535 ","End":"04:33.160","Text":"where in the center here,"},{"Start":"04:33.160 ","End":"04:37.625","Text":"we have a duct something going through like for instance,"},{"Start":"04:37.625 ","End":"04:40.580","Text":"you may have in the kidneys and these cells,"},{"Start":"04:40.580 ","End":"04:44.365","Text":"so this would be 1 cell here."},{"Start":"04:44.365 ","End":"04:50.990","Text":"Yes, it contains a single nucleus and the walls,"},{"Start":"04:50.990 ","End":"04:53.905","Text":"of course, are very tightly connected to each other."},{"Start":"04:53.905 ","End":"04:57.450","Text":"Overall they looked like cubes."},{"Start":"04:57.450 ","End":"05:01.430","Text":"Next we have columnar epithelium, that\u0027s,"},{"Start":"05:01.430 ","End":"05:03.970","Text":"the cells look more like columns,"},{"Start":"05:03.970 ","End":"05:05.600","Text":"and in this picture,"},{"Start":"05:05.600 ","End":"05:08.375","Text":"which is from the epithelium of the stomach,"},{"Start":"05:08.375 ","End":"05:10.680","Text":"we have individual cells,"},{"Start":"05:10.680 ","End":"05:15.370","Text":"I\u0027m marking them over here, which are columns."},{"Start":"05:15.370 ","End":"05:17.000","Text":"Here it\u0027s on its side,"},{"Start":"05:17.000 ","End":"05:20.795","Text":"here it\u0027s sitting more upright."},{"Start":"05:20.795 ","End":"05:26.635","Text":"These are various columns that are taller than they are wide."},{"Start":"05:26.635 ","End":"05:30.710","Text":"They\u0027re most commonly found in a single layer arrangement,"},{"Start":"05:30.710 ","End":"05:34.070","Text":"and they lie in most organs of the digestive tract,"},{"Start":"05:34.070 ","End":"05:38.240","Text":"whether it\u0027d be in the stomach or in the small intestine."},{"Start":"05:38.240 ","End":"05:43.490","Text":"The simple columnar epithelium is further divided into 2 different categories."},{"Start":"05:43.490 ","End":"05:45.995","Text":"They\u0027re ciliated and non-ciliated."},{"Start":"05:45.995 ","End":"05:48.080","Text":"Now, what are the cilia?"},{"Start":"05:48.080 ","End":"05:53.720","Text":"The cilia are little tails on some of these cells that we don\u0027t see in this picture."},{"Start":"05:53.720 ","End":"05:55.640","Text":"They can move,"},{"Start":"05:55.640 ","End":"06:01.930","Text":"and they enhance the movement of mucus over these surfaces."},{"Start":"06:01.930 ","End":"06:03.830","Text":"They can move trap particles,"},{"Start":"06:03.830 ","End":"06:06.230","Text":"for instance, out of the respiratory tract."},{"Start":"06:06.230 ","End":"06:07.520","Text":"When you cough,"},{"Start":"06:07.520 ","End":"06:11.435","Text":"you are removing small particles that the cilia"},{"Start":"06:11.435 ","End":"06:16.910","Text":"have moved to a place that you feel them so that you can get rid of them."},{"Start":"06:16.910 ","End":"06:19.820","Text":"Then we have the transitional epithelium."},{"Start":"06:19.820 ","End":"06:22.385","Text":"The transitional epithelium, as we mentioned,"},{"Start":"06:22.385 ","End":"06:24.725","Text":"may have different shapes of cells,"},{"Start":"06:24.725 ","End":"06:27.545","Text":"multiple layers of epithelial cells which can"},{"Start":"06:27.545 ","End":"06:31.325","Text":"contract and expand in order to adapt to the degree of the extension needed."},{"Start":"06:31.325 ","End":"06:33.200","Text":"Here we see a picture of"},{"Start":"06:33.200 ","End":"06:39.229","Text":"various sized cells that can change their shape from the interior,"},{"Start":"06:39.229 ","End":"06:41.900","Text":"from the epithelium of the bladder."},{"Start":"06:41.900 ","End":"06:44.900","Text":"These cells line, as we just said,"},{"Start":"06:44.900 ","End":"06:48.500","Text":"the urinary system and particularly the bladder and the ureter."},{"Start":"06:48.500 ","End":"06:51.920","Text":"That\u0027s where the urine goes out of the bladder,"},{"Start":"06:51.920 ","End":"06:54.785","Text":"and it\u0027s known as the urothelium."},{"Start":"06:54.785 ","End":"06:57.375","Text":"Here these cells change shape."},{"Start":"06:57.375 ","End":"06:59.180","Text":"When the urinary bladder fills,"},{"Start":"06:59.180 ","End":"07:04.850","Text":"the cells on the topmost layer that\u0027s over here, gets stretched."},{"Start":"07:04.850 ","End":"07:09.920","Text":"They get pushed by the liquid that\u0027s inside and therefore flattened."},{"Start":"07:09.920 ","End":"07:12.305","Text":"However, when the bladder is emptied,"},{"Start":"07:12.305 ","End":"07:15.990","Text":"they appear more cuboidal with a rounded shape,"},{"Start":"07:16.480 ","End":"07:24.150","Text":"as we said, after the urine has left and the urinary bladder is empty."}],"ID":27301},{"Watched":false,"Name":"Muscle tissue","Duration":"6m 8s","ChapterTopicVideoID":26395,"CourseChapterTopicPlaylistID":255406,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.815","Text":"Now let\u0027s look at a different tissue,"},{"Start":"00:04.815 ","End":"00:08.580","Text":"another basic tissue, muscle tissues."},{"Start":"00:08.580 ","End":"00:13.620","Text":"They are responsible for almost all types of body movement."},{"Start":"00:13.620 ","End":"00:18.884","Text":"They consist of filaments of proteins that are called actin and myosin."},{"Start":"00:18.884 ","End":"00:26.055","Text":"These actin and myosin proteins interact together to enable muscles to contract."},{"Start":"00:26.055 ","End":"00:29.790","Text":"The main functions of muscles are to produce skeletal movement."},{"Start":"00:29.790 ","End":"00:31.770","Text":"That is to be able to move, say,"},{"Start":"00:31.770 ","End":"00:36.620","Text":"various body parts to maintain the posture and body position so that you can"},{"Start":"00:36.620 ","End":"00:42.200","Text":"stand up straight or stay in a particular position to support soft tissues."},{"Start":"00:42.200 ","End":"00:48.290","Text":"That is ones that don\u0027t have bones in them so that they can maintain their structure."},{"Start":"00:48.290 ","End":"00:52.760","Text":"To guard entrances and exits, say the mouth,"},{"Start":"00:52.760 ","End":"00:56.150","Text":"let\u0027s say to keep the mouth closed, let\u0027s say,"},{"Start":"00:56.150 ","End":"01:00.770","Text":"or to keep our anus closed when it needs to be closed."},{"Start":"01:00.770 ","End":"01:04.145","Text":"Those are supported all by tissues to"},{"Start":"01:04.145 ","End":"01:08.780","Text":"maintain body temperature because it turns out that the muscles"},{"Start":"01:08.780 ","End":"01:12.980","Text":"burn good part of the glucose in our body"},{"Start":"01:12.980 ","End":"01:18.460","Text":"and the amount of heat that is produced is used to maintain body temperature."},{"Start":"01:18.460 ","End":"01:23.510","Text":"It also is a storage facilities stores nutrients."},{"Start":"01:23.510 ","End":"01:26.750","Text":"It\u0027s a reserve place."},{"Start":"01:26.750 ","End":"01:29.195","Text":"There are different muscle types."},{"Start":"01:29.195 ","End":"01:30.995","Text":"There are 3 different types."},{"Start":"01:30.995 ","End":"01:32.705","Text":"There is skeletal,"},{"Start":"01:32.705 ","End":"01:37.250","Text":"that is on the skeleton that helps us move."},{"Start":"01:37.250 ","End":"01:39.425","Text":"There\u0027s cardiac, that\u0027s our heart."},{"Start":"01:39.425 ","End":"01:42.870","Text":"That\u0027s a very particular kind as you can see here."},{"Start":"01:42.870 ","End":"01:47.510","Text":"There\u0027s something called smooth muscle which looks a little different"},{"Start":"01:47.510 ","End":"01:52.070","Text":"and it\u0027s also found in the intestines, for instance."},{"Start":"01:52.070 ","End":"01:55.430","Text":"Now the differences between these different muscle types are"},{"Start":"01:55.430 ","End":"01:59.210","Text":"the presence or absence of striations or bands."},{"Start":"01:59.210 ","End":"02:01.370","Text":"You can see these striations,"},{"Start":"02:01.370 ","End":"02:06.080","Text":"these lines that go up and down in both the skeletal and the cardiac muscle,"},{"Start":"02:06.080 ","End":"02:08.615","Text":"they\u0027re missing in smooth muscle, as we\u0027ll see in a minute,"},{"Start":"02:08.615 ","End":"02:12.995","Text":"the number and location of the nuclei inside the cells."},{"Start":"02:12.995 ","End":"02:16.340","Text":"It turns out that skeletal muscles, for instance,"},{"Start":"02:16.340 ","End":"02:19.850","Text":"have multiple nuclei in the same cell."},{"Start":"02:19.850 ","End":"02:22.910","Text":"Multinucleated cells is an unusual thing,"},{"Start":"02:22.910 ","End":"02:26.255","Text":"whereas the other muscles don\u0027t."},{"Start":"02:26.255 ","End":"02:33.500","Text":"Another difference is whether they contract voluntarily or involuntarily."},{"Start":"02:33.500 ","End":"02:40.835","Text":"Voluntarily means that your brain sends a message that you want to contract muscle say,"},{"Start":"02:40.835 ","End":"02:43.405","Text":"to move an arm or a leg or something like that."},{"Start":"02:43.405 ","End":"02:46.165","Text":"But there are other muscles like say your heart muscle,"},{"Start":"02:46.165 ","End":"02:48.160","Text":"which you can\u0027t control directly."},{"Start":"02:48.160 ","End":"02:51.775","Text":"Or the muscles that are in your intestine that you can\u0027t control directly."},{"Start":"02:51.775 ","End":"02:56.235","Text":"They\u0027re controlled otherwise involuntary way."},{"Start":"02:56.235 ","End":"02:58.450","Text":"Of course, the location within the body,"},{"Start":"02:58.450 ","End":"03:00.340","Text":"as we\u0027ve mentioned before."},{"Start":"03:00.340 ","End":"03:03.175","Text":"Now let\u0027s look at skeletal muscle."},{"Start":"03:03.175 ","End":"03:06.640","Text":"Skeletal muscle has these striations,"},{"Start":"03:06.640 ","End":"03:11.590","Text":"these lines that you can see because the contractile apparatus is arranged in"},{"Start":"03:11.590 ","End":"03:13.750","Text":"such a way that the actin and"},{"Start":"03:13.750 ","End":"03:18.190","Text":"the myosin are interleaved and where they\u0027re particularly interleaved,"},{"Start":"03:18.190 ","End":"03:20.580","Text":"you see this striation,"},{"Start":"03:20.580 ","End":"03:25.010","Text":"this line that you see very clearly in skeletal muscle."},{"Start":"03:25.010 ","End":"03:29.660","Text":"The cells are relatively long and they are multinucleated,"},{"Start":"03:29.660 ","End":"03:30.935","Text":"as we\u0027ve said before."},{"Start":"03:30.935 ","End":"03:34.070","Text":"They are under voluntary control."},{"Start":"03:34.070 ","End":"03:36.030","Text":"These are somatic nerves."},{"Start":"03:36.030 ","End":"03:40.240","Text":"So these are nerves that we can voluntarily trigger."},{"Start":"03:40.240 ","End":"03:46.925","Text":"Of course, most of the skeletal muscles are attached to the skeleton, to the bones."},{"Start":"03:46.925 ","End":"03:52.925","Text":"They\u0027re attached by these bundles of collagen fibers that are called tendons."},{"Start":"03:52.925 ","End":"03:57.530","Text":"Now cardiac muscle, however, has different properties."},{"Start":"03:57.530 ","End":"04:00.185","Text":"First of all, it\u0027s found only in the heart."},{"Start":"04:00.185 ","End":"04:03.905","Text":"The cells are also cross striated."},{"Start":"04:03.905 ","End":"04:08.990","Text":"They have these striations just as the skeletal muscles do."},{"Start":"04:08.990 ","End":"04:16.118","Text":"It, however, only has a single nucleus in each cell,"},{"Start":"04:16.118 ","End":"04:18.590","Text":"the cardiac muscles are not multinucleated."},{"Start":"04:18.590 ","End":"04:24.530","Text":"They only have a single nucleus and they\u0027re located near the center of each of the cells."},{"Start":"04:24.530 ","End":"04:28.880","Text":"But the cells now are not influenced voluntarily."},{"Start":"04:28.880 ","End":"04:36.385","Text":"They are influenced or they\u0027re set off to contract by the autonomous nervous system."},{"Start":"04:36.385 ","End":"04:38.660","Text":"That\u0027s to the heart, of course,"},{"Start":"04:38.660 ","End":"04:41.405","Text":"speeds up or slows down depending on what it needs to do."},{"Start":"04:41.405 ","End":"04:45.545","Text":"But it\u0027s not a conscious thing that you can do."},{"Start":"04:45.545 ","End":"04:54.445","Text":"The cells are connected to each other by these things called intercalated discs and"},{"Start":"04:54.445 ","End":"05:03.670","Text":"that makes the entire muscle that\u0027s inside the heart work as a single functional organ."},{"Start":"05:03.670 ","End":"05:07.105","Text":"Now, smooth muscle is different again."},{"Start":"05:07.105 ","End":"05:10.930","Text":"Here too, you have a single centrally located nucleus."},{"Start":"05:10.930 ","End":"05:13.435","Text":"They are not multinucleated either."},{"Start":"05:13.435 ","End":"05:16.225","Text":"However, they do not have striations."},{"Start":"05:16.225 ","End":"05:19.870","Text":"You don\u0027t see the striations because the actin and"},{"Start":"05:19.870 ","End":"05:24.325","Text":"myosin are not as regularly distributed throughout the cell."},{"Start":"05:24.325 ","End":"05:31.235","Text":"They are also set off involuntary constriction by an autonomic nervous system."},{"Start":"05:31.235 ","End":"05:33.800","Text":"Of course, it\u0027s different than the 1 in the hearts,"},{"Start":"05:33.800 ","End":"05:36.455","Text":"and it\u0027s in response to local conditions."},{"Start":"05:36.455 ","End":"05:38.090","Text":"Whether you need, for instance,"},{"Start":"05:38.090 ","End":"05:44.434","Text":"your intestine to have some peristalsis to move the food inside the intestine,"},{"Start":"05:44.434 ","End":"05:49.415","Text":"contraction would be set off by this involuntary mechanism."},{"Start":"05:49.415 ","End":"05:52.460","Text":"These smooth muscles are present, for instance,"},{"Start":"05:52.460 ","End":"05:55.880","Text":"in the walls of blood vessels, constricting blood vessels,"},{"Start":"05:55.880 ","End":"06:00.860","Text":"especially the arteries and the tubes of the digestive, as we\u0027d said,"},{"Start":"06:00.860 ","End":"06:04.280","Text":"the digestive system and also reproductive systems to move"},{"Start":"06:04.280 ","End":"06:09.240","Text":"things through the reproductive tract as is needed."}],"ID":27302},{"Watched":false,"Name":"Nervous tissue","Duration":"3m 32s","ChapterTopicVideoID":26396,"CourseChapterTopicPlaylistID":255406,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.583","Text":"Now we\u0027re going to be looking at the last kind of tissue,"},{"Start":"00:04.583 ","End":"00:09.090","Text":"a very specialized tissue called nervous tissue."},{"Start":"00:09.090 ","End":"00:11.535","Text":"These cells, as you know,"},{"Start":"00:11.535 ","End":"00:17.145","Text":"are very specialized to receive and transmit electrical impulses."},{"Start":"00:17.145 ","End":"00:19.335","Text":"You can see in the picture here they look quite"},{"Start":"00:19.335 ","End":"00:22.020","Text":"different than the other kinds of cells that we\u0027ve seen."},{"Start":"00:22.020 ","End":"00:24.990","Text":"Notice long projections."},{"Start":"00:24.990 ","End":"00:31.425","Text":"These cells can be distinguished by 2 main classes of cells."},{"Start":"00:31.425 ","End":"00:33.690","Text":"First, there are neurons."},{"Start":"00:33.690 ","End":"00:37.625","Text":"These are the nerve cells that you can see here in yellow."},{"Start":"00:37.625 ","End":"00:42.095","Text":"Those propagate information via the electrochemical impulses,"},{"Start":"00:42.095 ","End":"00:44.045","Text":"as we mentioned a minute ago."},{"Start":"00:44.045 ","End":"00:45.785","Text":"But in addition to that,"},{"Start":"00:45.785 ","End":"00:50.750","Text":"nerve tissues contain additional cells, glial cells."},{"Start":"00:50.750 ","End":"00:55.135","Text":"They\u0027re called neural glia, in fact."},{"Start":"00:55.135 ","End":"01:01.330","Text":"Those are different cells that are in different colors here that support the neurons."},{"Start":"01:01.330 ","End":"01:04.580","Text":"The nervous tissue is made up not only of the neurons,"},{"Start":"01:04.580 ","End":"01:07.595","Text":"but by supporting cells as well."},{"Start":"01:07.595 ","End":"01:09.785","Text":"Now let\u0027s see what the neurons are."},{"Start":"01:09.785 ","End":"01:16.085","Text":"The neurons themselves have a very large structure and they have a central nucleus."},{"Start":"01:16.085 ","End":"01:22.520","Text":"There\u0027s this part of the cell that is large and a little bit fatter."},{"Start":"01:22.520 ","End":"01:27.345","Text":"It contains most of what\u0027s usually found in a cell."},{"Start":"01:27.345 ","End":"01:28.880","Text":"In addition to that,"},{"Start":"01:28.880 ","End":"01:30.980","Text":"there are these dendrites,"},{"Start":"01:30.980 ","End":"01:34.729","Text":"those are these projections that project out from the cell,"},{"Start":"01:34.729 ","End":"01:37.700","Text":"and sometimes there is a single projection,"},{"Start":"01:37.700 ","End":"01:39.200","Text":"a very long one,"},{"Start":"01:39.200 ","End":"01:41.285","Text":"which is called an axon."},{"Start":"01:41.285 ","End":"01:46.385","Text":"Those are the structures of the cells that are particularly important"},{"Start":"01:46.385 ","End":"01:52.055","Text":"in transmitting impulses in particularly a long distance."},{"Start":"01:52.055 ","End":"01:54.890","Text":"Now, we\u0027ll see later in another video what"},{"Start":"01:54.890 ","End":"01:57.890","Text":"the differences are between different kinds of neurons."},{"Start":"01:57.890 ","End":"02:00.245","Text":"But for now, let\u0027s just stick with this."},{"Start":"02:00.245 ","End":"02:02.695","Text":"Now, what about the additional cells?"},{"Start":"02:02.695 ","End":"02:04.640","Text":"In addition to the neurons,"},{"Start":"02:04.640 ","End":"02:06.425","Text":"we have the glia, as we mentioned,"},{"Start":"02:06.425 ","End":"02:11.690","Text":"but the glia also separated into different kinds of cells."},{"Start":"02:11.690 ","End":"02:14.600","Text":"There are astrocytes, as you can see here,"},{"Start":"02:14.600 ","End":"02:17.225","Text":"that have a different structure than the other kinds of cells."},{"Start":"02:17.225 ","End":"02:20.900","Text":"Those regulate the chemical environment of the nerve cell."},{"Start":"02:20.900 ","End":"02:24.680","Text":"They provide some of the environment that\u0027s necessary."},{"Start":"02:24.680 ","End":"02:28.135","Text":"There are oligodendrocytes."},{"Start":"02:28.135 ","End":"02:31.240","Text":"Oligodendrocytes."},{"Start":"02:31.240 ","End":"02:33.500","Text":"What do they do? Here they are?"},{"Start":"02:33.500 ","End":"02:39.000","Text":"They insulate the axon with myelin quite efficiently."},{"Start":"02:39.000 ","End":"02:45.875","Text":"Myelin is a chemical which is produced by these oligodendrocytes and it\u0027s an insulator."},{"Start":"02:45.875 ","End":"02:51.020","Text":"That\u0027s what helps have the electrical signal stay on the cell"},{"Start":"02:51.020 ","End":"02:56.165","Text":"or in the cell as the electrical signal moves down the axon."},{"Start":"02:56.165 ","End":"02:59.000","Text":"It\u0027s insulated by myelin."},{"Start":"02:59.000 ","End":"03:01.715","Text":"Then there are other glial cells that you can see here,"},{"Start":"03:01.715 ","End":"03:06.880","Text":"and they support the nutritional and waste requirements of a neuron."},{"Start":"03:06.880 ","End":"03:11.120","Text":"Now notice that the kinds of cells that are found"},{"Start":"03:11.120 ","End":"03:15.595","Text":"in the nervous system are somewhat different in the central nervous system."},{"Start":"03:15.595 ","End":"03:17.360","Text":"That would be, for instance,"},{"Start":"03:17.360 ","End":"03:22.190","Text":"the brain and the spinal cord and the axons that move our muscles and so on,"},{"Start":"03:22.190 ","End":"03:26.690","Text":"and the peripheral nervous system that you might have,"},{"Start":"03:26.690 ","End":"03:31.620","Text":"let\u0027s say, operating some of the autonomous cells in the body."}],"ID":27303}],"Thumbnail":null,"ID":255406},{"Name":"Homeostasis","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Homeostasis","Duration":"11m 5s","ChapterTopicVideoID":26397,"CourseChapterTopicPlaylistID":255407,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.500","Text":"Welcome back. We\u0027ve been discussing various tissues,"},{"Start":"00:04.500 ","End":"00:09.990","Text":"and now we\u0027re going to start thinking about how the various tissues work together."},{"Start":"00:09.990 ","End":"00:13.410","Text":"We\u0027re going to discuss homeostasis."},{"Start":"00:13.410 ","End":"00:15.420","Text":"What is homeostasis?"},{"Start":"00:15.420 ","End":"00:20.714","Text":"Homeostasis aims to keep internal conditions at a steady state,"},{"Start":"00:20.714 ","End":"00:23.100","Text":"regardless of the external environment,"},{"Start":"00:23.100 ","End":"00:26.445","Text":"so that if the temperature goes down,"},{"Start":"00:26.445 ","End":"00:31.530","Text":"the body may try to warm itself up so that it maintains a constant temperature."},{"Start":"00:31.530 ","End":"00:34.440","Text":"The same thing can be true of the pH in"},{"Start":"00:34.440 ","End":"00:39.690","Text":"the blood system and the glucose levels in the blood and all sorts of other things."},{"Start":"00:39.690 ","End":"00:41.835","Text":"So let\u0027s look at this more in depth."},{"Start":"00:41.835 ","End":"00:46.430","Text":"If conditions stray too far from a particular set point,"},{"Start":"00:46.430 ","End":"00:53.220","Text":"then there are various mechanisms that kick in that we call homeostatic mechanisms."},{"Start":"00:53.220 ","End":"00:55.980","Text":"You see this guy is sitting above the clouds."},{"Start":"00:55.980 ","End":"00:59.000","Text":"He climbed up here. There\u0027s not a lot to breathe up here,"},{"Start":"00:59.000 ","End":"01:01.090","Text":"not a lot of oxygen."},{"Start":"01:01.090 ","End":"01:04.460","Text":"But he has to maintain his body working well,"},{"Start":"01:04.460 ","End":"01:08.885","Text":"even though the amount of oxygen outside is not very high."},{"Start":"01:08.885 ","End":"01:10.610","Text":"The set point, though,"},{"Start":"01:10.610 ","End":"01:14.660","Text":"can potentially change over time, but still,"},{"Start":"01:14.660 ","End":"01:19.606","Text":"if there can be homeostasis that will work towards setting a new set point,"},{"Start":"01:19.606 ","End":"01:22.370","Text":"as we\u0027ll see some organisms when they hibernate,"},{"Start":"01:22.370 ","End":"01:24.800","Text":"might change their set point."},{"Start":"01:24.800 ","End":"01:28.730","Text":"Another thing that can happen is there can be acclimatization."},{"Start":"01:28.730 ","End":"01:30.325","Text":"For instance, this climber,"},{"Start":"01:30.325 ","End":"01:32.915","Text":"he may have to change 1 organ system"},{"Start":"01:32.915 ","End":"01:36.050","Text":"in order to maintain a set point in another organ system."},{"Start":"01:36.050 ","End":"01:38.640","Text":"That\u0027s in climbing to an altitude,"},{"Start":"01:38.640 ","End":"01:41.825","Text":"and we\u0027ll look at that in more detail in a minute."},{"Start":"01:41.825 ","End":"01:45.420","Text":"What are various mechanisms of homeostasis?"},{"Start":"01:45.420 ","End":"01:48.560","Text":"First of all, we know that the goal of homeostasis is"},{"Start":"01:48.560 ","End":"01:53.520","Text":"the maintenance of equilibrium around a particular set point."},{"Start":"01:53.520 ","End":"01:56.360","Text":"What would happen is that there can be"},{"Start":"01:56.360 ","End":"01:59.720","Text":"a particular stimulus that changes a particular variable,"},{"Start":"01:59.720 ","End":"02:01.835","Text":"let\u0027s say, the temperature."},{"Start":"02:01.835 ","End":"02:06.343","Text":"That then will be sensed by a receptor,"},{"Start":"02:06.343 ","End":"02:08.550","Text":"often that\u0027s in the brain,"},{"Start":"02:08.550 ","End":"02:09.960","Text":"and then there will be"},{"Start":"02:09.960 ","End":"02:15.650","Text":"neuronal signals that will go from the receptor to some control center."},{"Start":"02:15.650 ","End":"02:18.970","Text":"It\u0027s usually the brain that does this."},{"Start":"02:18.970 ","End":"02:25.160","Text":"Then the brain or the control sensor will send some message to an effector."},{"Start":"02:25.160 ","End":"02:31.605","Text":"The effector then is going to elicit some response,"},{"Start":"02:31.605 ","End":"02:34.610","Text":"and that could be a muscle or"},{"Start":"02:34.610 ","End":"02:39.700","Text":"a gland which responds and returns the variable to the set point."},{"Start":"02:39.700 ","End":"02:41.986","Text":"So something will change."},{"Start":"02:41.986 ","End":"02:43.160","Text":"If its temperature,"},{"Start":"02:43.160 ","End":"02:44.900","Text":"then you have to increase the temperature,"},{"Start":"02:44.900 ","End":"02:51.655","Text":"then a muscle might work harder in order to increase the temperature."},{"Start":"02:51.655 ","End":"02:54.890","Text":"So here are some different examples there."},{"Start":"02:54.890 ","End":"02:59.395","Text":"One kind of mechanism is a negative feedback mechanism,"},{"Start":"02:59.395 ","End":"03:02.310","Text":"and let\u0027s look at what we have here."},{"Start":"03:02.310 ","End":"03:07.170","Text":"Those would be homeostatic processes that change the direction of a stimulus."},{"Start":"03:07.170 ","End":"03:08.773","Text":"So you have a stimulus, let\u0027s say,"},{"Start":"03:08.773 ","End":"03:11.365","Text":"the body temperature increases,"},{"Start":"03:11.365 ","End":"03:13.605","Text":"so that\u0027s going to be the stimulus,"},{"Start":"03:13.605 ","End":"03:19.550","Text":"and the homeostatic process is going to lower the temperature."},{"Start":"03:19.550 ","End":"03:21.320","Text":"The body temperature increases,"},{"Start":"03:21.320 ","End":"03:24.570","Text":"and the stimulus will decrease it."},{"Start":"03:24.570 ","End":"03:31.100","Text":"In this example, if the normal body temperature of humans is between 36 and 38 degrees C,"},{"Start":"03:31.100 ","End":"03:35.450","Text":"then the hypothalamus in the brain will activate"},{"Start":"03:35.450 ","End":"03:39.710","Text":"a cooling mechanism if the body temperature increases in various ways,"},{"Start":"03:39.710 ","End":"03:42.410","Text":"so blood vessels in the skin might dilate."},{"Start":"03:42.410 ","End":"03:45.515","Text":"You know that when you get hot you turn red, that\u0027s why,"},{"Start":"03:45.515 ","End":"03:51.860","Text":"because the blood vessels dilate so that you can lose some heat from your blood,"},{"Start":"03:51.860 ","End":"03:53.870","Text":"and in addition to that, you may sweat."},{"Start":"03:53.870 ","End":"03:56.060","Text":"Sweat glands may operate"},{"Start":"03:56.060 ","End":"04:00.445","Text":"releasing water to the surface so it evaporates and then temperature decreases."},{"Start":"04:00.445 ","End":"04:03.619","Text":"On the other hand, if your body temperature decreases,"},{"Start":"04:03.619 ","End":"04:05.300","Text":"you\u0027re in a cold area, again,"},{"Start":"04:05.300 ","End":"04:06.900","Text":"the brain may sense it,"},{"Start":"04:06.900 ","End":"04:08.465","Text":"and the opposite happens."},{"Start":"04:08.465 ","End":"04:11.405","Text":"The blood vessels will constrict,"},{"Start":"04:11.405 ","End":"04:13.925","Text":"and you may shiver,"},{"Start":"04:13.925 ","End":"04:15.628","Text":"leaving out heat,"},{"Start":"04:15.628 ","End":"04:18.530","Text":"body temperature increases going back to normal."},{"Start":"04:18.530 ","End":"04:22.835","Text":"You can have an increase or decrease in the stimulus back to a normal value,"},{"Start":"04:22.835 ","End":"04:26.090","Text":"and those can be temperature, we said glucose,"},{"Start":"04:26.090 ","End":"04:30.290","Text":"pH, blood calcium, there are all sorts of things of these sorts."},{"Start":"04:30.290 ","End":"04:33.529","Text":"Now in addition to negative feedback mechanisms,"},{"Start":"04:33.529 ","End":"04:36.950","Text":"there are also positive feedback loops"},{"Start":"04:36.950 ","End":"04:40.640","Text":"that don\u0027t necessarily maintain a particular set point,"},{"Start":"04:40.640 ","End":"04:45.650","Text":"but they do respond to a stimulus that\u0027s on the outside,"},{"Start":"04:45.650 ","End":"04:49.495","Text":"and it may potentially strengthen the response to a stimulus."},{"Start":"04:49.495 ","End":"04:59.980","Text":"In this example, we have a baby who is hungry and is sucking at the breast of its mother."},{"Start":"04:59.980 ","End":"05:01.700","Text":"What does that do?"},{"Start":"05:01.700 ","End":"05:07.910","Text":"What it does to the mother is that there is a nerve impulse"},{"Start":"05:07.910 ","End":"05:14.509","Text":"which is sent from her breast to the hypothalamus in her brain,"},{"Start":"05:14.509 ","End":"05:18.330","Text":"which in turn, through nerves,"},{"Start":"05:18.330 ","End":"05:21.700","Text":"go to the posterior pituitary,"},{"Start":"05:21.700 ","End":"05:23.540","Text":"all this is in the brain."},{"Start":"05:23.540 ","End":"05:29.930","Text":"Then a chemical called oxytocin is released into the blood,"},{"Start":"05:29.930 ","End":"05:32.270","Text":"which goes back to the breast,"},{"Start":"05:32.270 ","End":"05:37.685","Text":"and that stimulates the milk glands to produce"},{"Start":"05:37.685 ","End":"05:44.160","Text":"milk and for the muscle cells to contract so that the baby then can drink."},{"Start":"05:44.160 ","End":"05:47.510","Text":"This is a positive feedback loop."},{"Start":"05:47.510 ","End":"05:50.960","Text":"It\u0027s not a homeostatic static process,"},{"Start":"05:50.960 ","End":"05:55.217","Text":"and we have this oxytocin that we just described."},{"Start":"05:55.217 ","End":"05:57.845","Text":"Another example is blood clotting."},{"Start":"05:57.845 ","End":"06:03.005","Text":"When blood begins to leak through a blood vessel, let\u0027s say, you\u0027re a cut,"},{"Start":"06:03.005 ","End":"06:05.810","Text":"then there\u0027s a whole process that occurs to"},{"Start":"06:05.810 ","End":"06:10.010","Text":"stop the blood from coming out of the blood vessel,"},{"Start":"06:10.010 ","End":"06:11.270","Text":"that is, to clot."},{"Start":"06:11.270 ","End":"06:14.510","Text":"That\u0027s a positive feedback loop which is"},{"Start":"06:14.510 ","End":"06:18.725","Text":"responding to a particular stimulus on the outside."},{"Start":"06:18.725 ","End":"06:22.355","Text":"Let\u0027s look more now at homeostasis."},{"Start":"06:22.355 ","End":"06:25.820","Text":"In homeostasis, there\u0027s a set point, as we mentioned."},{"Start":"06:25.820 ","End":"06:29.420","Text":"There is a certain range and that can change sometimes"},{"Start":"06:29.420 ","End":"06:32.870","Text":"with age or sometimes there can be a cyclic variation,"},{"Start":"06:32.870 ","End":"06:36.980","Text":"like you can see here around the set point in body temperatures."},{"Start":"06:36.980 ","End":"06:41.340","Text":"That can also happen with blood pressure as well."},{"Start":"06:41.340 ","End":"06:43.190","Text":"There\u0027s a feedback loop,"},{"Start":"06:43.190 ","End":"06:46.945","Text":"as we saw before, that works to maintain the new setting."},{"Start":"06:46.945 ","End":"06:50.200","Text":"As an example, in addition to temperature,"},{"Start":"06:50.200 ","End":"06:52.100","Text":"we have blood pressure."},{"Start":"06:52.100 ","End":"06:54.725","Text":"Now let\u0027s look at acclimatization,"},{"Start":"06:54.725 ","End":"06:57.145","Text":"as we described previously."},{"Start":"06:57.145 ","End":"07:03.875","Text":"There are changes in the body organs that maintain a particular set point."},{"Start":"07:03.875 ","End":"07:07.610","Text":"An example would be a set point of the number"},{"Start":"07:07.610 ","End":"07:12.160","Text":"of red blood cells that are in our body that carry oxygen."},{"Start":"07:12.160 ","End":"07:18.605","Text":"In this case, if you go to a higher altitude,"},{"Start":"07:18.605 ","End":"07:25.718","Text":"there is less oxygen in your blood and that is sensed by sensors in the kidney and liver."},{"Start":"07:25.718 ","End":"07:29.990","Text":"There is a protein called erythropoietin,"},{"Start":"07:29.990 ","End":"07:32.720","Text":"it\u0027s a hormone really,"},{"Start":"07:32.720 ","End":"07:35.762","Text":"that\u0027s released into the bloodstream,"},{"Start":"07:35.762 ","End":"07:42.130","Text":"and it is sensed by sensors in the bone marrow."},{"Start":"07:42.130 ","End":"07:47.570","Text":"The bone marrow then interprets this as the need to create more red blood cells."},{"Start":"07:47.570 ","End":"07:50.120","Text":"So you have more red blood cells produced,"},{"Start":"07:50.120 ","End":"07:54.125","Text":"the more red blood cells that can carry more oxygen,"},{"Start":"07:54.125 ","End":"07:59.690","Text":"and we have normal blood oxygen levels that are returned at the higher level."},{"Start":"07:59.690 ","End":"08:03.530","Text":"Of course, this takes a couple of days and that\u0027s the reason that"},{"Start":"08:03.530 ","End":"08:07.925","Text":"you have to acclimate when you\u0027re climbing to high altitudes."},{"Start":"08:07.925 ","End":"08:11.840","Text":"This thing can also happen seasonally in"},{"Start":"08:11.840 ","End":"08:17.600","Text":"various animals and that can cause the change of the coat of an animal."},{"Start":"08:17.600 ","End":"08:22.504","Text":"We all know that dogs may shed in the spring,"},{"Start":"08:22.504 ","End":"08:28.220","Text":"and they develop warmer coats in the fall when it gets cold."},{"Start":"08:28.220 ","End":"08:33.275","Text":"Now, there is something else called thermoregulation in"},{"Start":"08:33.275 ","End":"08:36.160","Text":"various organisms that must maintain"},{"Start":"08:36.160 ","End":"08:40.360","Text":"the constant internal temperature to keep enzymes efficient and avoid denaturation."},{"Start":"08:40.360 ","End":"08:44.170","Text":"Why? Because proteins, including enzymes,"},{"Start":"08:44.170 ","End":"08:49.570","Text":"begin to denature with high heat around 50 degrees in mammals."},{"Start":"08:49.570 ","End":"08:51.595","Text":"They denature, they change their shape,"},{"Start":"08:51.595 ","End":"08:52.960","Text":"and no longer have the same shape,"},{"Start":"08:52.960 ","End":"08:55.135","Text":"and so they don\u0027t behave as well."},{"Start":"08:55.135 ","End":"09:00.234","Text":"The enzyme activity in those proteins will decrease,"},{"Start":"09:00.234 ","End":"09:02.190","Text":"this is a general thing,"},{"Start":"09:02.190 ","End":"09:05.715","Text":"by about half for every 10 degrees drop in temperature."},{"Start":"09:05.715 ","End":"09:10.255","Text":"Therefore, it\u0027s important to keep the temperature within a certain range."},{"Start":"09:10.255 ","End":"09:13.990","Text":"Some fish can withstand freezing solid, even,"},{"Start":"09:13.990 ","End":"09:17.364","Text":"and return to normal with thawing,"},{"Start":"09:17.364 ","End":"09:19.940","Text":"but this is an unusual situation."},{"Start":"09:19.940 ","End":"09:27.840","Text":"So we divide thermal homeostasis into endotherms and ectotherms,"},{"Start":"09:27.840 ","End":"09:30.875","Text":"\"ecto\" outside and \"endo\" inside."},{"Start":"09:30.875 ","End":"09:34.730","Text":"What does that mean? The ectotherms do not control their body temperature."},{"Start":"09:34.730 ","End":"09:39.020","Text":"It\u0027s the outside surrounding that controls their body temperature,"},{"Start":"09:39.020 ","End":"09:43.520","Text":"and the endotherms rely on their internal sources for body temperature,"},{"Start":"09:43.520 ","End":"09:46.775","Text":"but they can exhibit extremes in temperature, nonetheless."},{"Start":"09:46.775 ","End":"09:50.210","Text":"Then there are these poikilotherms."},{"Start":"09:50.210 ","End":"09:54.204","Text":"They have constantly varying internal temperatures."},{"Start":"09:54.204 ","End":"09:58.310","Text":"They\u0027re birds and mammals that allow their body temperature"},{"Start":"09:58.310 ","End":"10:03.170","Text":"to vary during certain time periods, like hibernation."},{"Start":"10:03.170 ","End":"10:07.800","Text":"Some of the insects do that and as do other invertebrates."},{"Start":"10:07.800 ","End":"10:12.950","Text":"The homeotherms maintain a relatively constant temperature like mammals."},{"Start":"10:12.950 ","End":"10:18.275","Text":"We know we have a very closely controlled body temperature."},{"Start":"10:18.275 ","End":"10:20.600","Text":"Now how do we get rid of heat?"},{"Start":"10:20.600 ","End":"10:25.025","Text":"There are different ways we can radiate it."},{"Start":"10:25.025 ","End":"10:28.970","Text":"It can just leave by radiation."},{"Start":"10:28.970 ","End":"10:31.355","Text":"You can see it just comes off."},{"Start":"10:31.355 ","End":"10:34.205","Text":"It can evaporate water,"},{"Start":"10:34.205 ","End":"10:38.030","Text":"like dogs will pant and that"},{"Start":"10:38.030 ","End":"10:42.755","Text":"reduces the temperature of their bodies because there\u0027s evaporation from their tongues."},{"Start":"10:42.755 ","End":"10:44.660","Text":"There\u0027s convection."},{"Start":"10:44.660 ","End":"10:49.430","Text":"We can have wind blowing by us and that removes some of the temperature,"},{"Start":"10:49.430 ","End":"10:51.215","Text":"or we can have conduction."},{"Start":"10:51.215 ","End":"10:55.685","Text":"I would have made this away from this iguana."},{"Start":"10:55.685 ","End":"10:59.600","Text":"The temperature then can either dissipate from it,"},{"Start":"10:59.600 ","End":"11:05.460","Text":"or it can heat the iguana if it needs to be heated from the land."}],"ID":27324},{"Watched":false,"Name":"Thermoregulation and Fever","Duration":"5m 59s","ChapterTopicVideoID":26399,"CourseChapterTopicPlaylistID":255407,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.610","Text":"Hi. Welcome back."},{"Start":"00:02.610 ","End":"00:10.139","Text":"We\u0027re now discussing heat conservation and dissipation in higher organisms,"},{"Start":"00:10.139 ","End":"00:14.055","Text":"and we\u0027ll start out by talking about body insulation."},{"Start":"00:14.055 ","End":"00:20.055","Text":"Animals conserve or dissipate heat in a variety of ways."},{"Start":"00:20.055 ","End":"00:21.840","Text":"First of all, as you\u0027ll remember,"},{"Start":"00:21.840 ","End":"00:25.005","Text":"there are different kind of animals."},{"Start":"00:25.005 ","End":"00:27.705","Text":"We\u0027re going to discuss endotherms here."},{"Start":"00:27.705 ","End":"00:31.320","Text":"These are animals that maintain their body temperature,"},{"Start":"00:31.320 ","End":"00:34.545","Text":"and they do this, first of all,"},{"Start":"00:34.545 ","End":"00:37.470","Text":"by having a certain insulation on"},{"Start":"00:37.470 ","End":"00:40.980","Text":"the outside of their bodies that can be either fur or feathers,"},{"Start":"00:40.980 ","End":"00:44.060","Text":"if they\u0027re birds, or fat,"},{"Start":"00:44.060 ","End":"00:47.450","Text":"actually, which also will insulate."},{"Start":"00:47.450 ","End":"00:50.513","Text":"Mammals, in addition, can shiver."},{"Start":"00:50.513 ","End":"00:58.091","Text":"You know that from yourselves and that can increase the heat that we produce."},{"Start":"00:58.091 ","End":"01:01.190","Text":"In addition to that, there can be other kinds of muscle activity."},{"Start":"01:01.190 ","End":"01:05.225","Text":"For instance, the production of goosebumps that we\u0027re also familiar with,"},{"Start":"01:05.225 ","End":"01:07.730","Text":"which makes our hair stand up on end,"},{"Start":"01:07.730 ","End":"01:08.825","Text":"and if we had more hair,"},{"Start":"01:08.825 ","End":"01:10.800","Text":"like other animals,"},{"Start":"01:10.800 ","End":"01:13.420","Text":"then it might insulate us better."},{"Start":"01:13.420 ","End":"01:19.925","Text":"In addition, there turns out that the body fat is very significant in insulating"},{"Start":"01:19.925 ","End":"01:23.390","Text":"an animal and the loss of significant amounts of"},{"Start":"01:23.390 ","End":"01:28.030","Text":"body fats can lower the ability to conserve heat."},{"Start":"01:28.030 ","End":"01:35.835","Text":"Now let\u0027s see how the body does its thermoregulation, regulates its temperature."},{"Start":"01:35.835 ","End":"01:39.650","Text":"First of all, it\u0027s a fairly complicated system,"},{"Start":"01:39.650 ","End":"01:43.790","Text":"and 1 component of it is neural control, that is,"},{"Start":"01:43.790 ","End":"01:48.754","Text":"the nervous system is very important to the thermoregulation."},{"Start":"01:48.754 ","End":"01:51.035","Text":"How does that happen? First of all,"},{"Start":"01:51.035 ","End":"01:54.355","Text":"the body temperature is monitored and"},{"Start":"01:54.355 ","End":"01:58.610","Text":"controlled by various temperature receptors that are around the body,"},{"Start":"01:58.610 ","End":"02:00.170","Text":"that are in the skin,"},{"Start":"02:00.170 ","End":"02:02.720","Text":"and in the periphery,"},{"Start":"02:02.720 ","End":"02:04.300","Text":"in the brain,"},{"Start":"02:04.300 ","End":"02:06.195","Text":"and in the skin."},{"Start":"02:06.195 ","End":"02:08.630","Text":"These receptors detect various changes in"},{"Start":"02:08.630 ","End":"02:13.384","Text":"the temperature of the blood that is flowing through those areas."},{"Start":"02:13.384 ","End":"02:15.680","Text":"So we\u0027re measuring, actually, the temperature of the blood."},{"Start":"02:15.680 ","End":"02:20.525","Text":"It\u0027s not so important for the body to know what the external temperature is."},{"Start":"02:20.525 ","End":"02:23.740","Text":"The body wants to know what the internal temperature is,"},{"Start":"02:23.740 ","End":"02:27.335","Text":"and so it measures the temperature in the blood,"},{"Start":"02:27.335 ","End":"02:32.600","Text":"and then there are signals that are sent to"},{"Start":"02:32.600 ","End":"02:40.445","Text":"the brain to a thermoregulatory center in the hypothalamus, which is in the brain."},{"Start":"02:40.445 ","End":"02:43.370","Text":"If the body temperature deviates from normal,"},{"Start":"02:43.370 ","End":"02:48.994","Text":"which is roundabout 37 degrees C or 98.6 Fahrenheit,"},{"Start":"02:48.994 ","End":"02:52.420","Text":"the hypothalamus and skin receptors send out electrical signals."},{"Start":"02:52.420 ","End":"02:57.330","Text":"This is the nervous system that trigger actions or behaviors,"},{"Start":"02:57.330 ","End":"03:01.040","Text":"and we\u0027ll see that sometimes the animal will behave differently if it\u0027s cold,"},{"Start":"03:01.040 ","End":"03:04.610","Text":"that increase or decrease heat loss,"},{"Start":"03:04.610 ","End":"03:07.015","Text":"depending on what the situation is."},{"Start":"03:07.015 ","End":"03:13.185","Text":"Now let\u0027s see how this signaling works."},{"Start":"03:13.185 ","End":"03:17.360","Text":"We\u0027re talking about the neural control of thermoregulation."},{"Start":"03:17.360 ","End":"03:27.125","Text":"1 example is what happens when there is an infection that changes our temperature,"},{"Start":"03:27.125 ","End":"03:29.465","Text":"say, gives us some fever."},{"Start":"03:29.465 ","End":"03:33.635","Text":"There are things that are called endogenous pyrogens."},{"Start":"03:33.635 ","End":"03:35.970","Text":"\"Pyro\", remember fire, is pyro,"},{"Start":"03:35.970 ","End":"03:38.990","Text":"things that change temperature. These are endogenous."},{"Start":"03:38.990 ","End":"03:40.460","Text":"They come from inside the body,"},{"Start":"03:40.460 ","End":"03:45.110","Text":"and those are substances that come from phagocytic leukocytes,"},{"Start":"03:45.110 ","End":"03:48.550","Text":"and they are capable of inducing fever."},{"Start":"03:48.550 ","End":"03:51.185","Text":"Let\u0027s look at the example below."},{"Start":"03:51.185 ","End":"03:53.810","Text":"Let\u0027s say that we have an infection."},{"Start":"03:53.810 ","End":"03:57.215","Text":"There\u0027s a bacterium that penetrates the body."},{"Start":"03:57.215 ","End":"03:58.505","Text":"In the bloodstream,"},{"Start":"03:58.505 ","End":"04:00.049","Text":"there are macrophages,"},{"Start":"04:00.049 ","End":"04:01.445","Text":"part of the immune system,"},{"Start":"04:01.445 ","End":"04:04.205","Text":"that engulf those bacteria."},{"Start":"04:04.205 ","End":"04:08.255","Text":"Those bacteria then are broken down,"},{"Start":"04:08.255 ","End":"04:12.815","Text":"and there are toxins that are released from the bacteria that"},{"Start":"04:12.815 ","End":"04:18.205","Text":"elicits a response from these macrophages to produce cytokines."},{"Start":"04:18.205 ","End":"04:22.505","Text":"Examples of cytokines can be interleukin-1 or TNF-Alpha."},{"Start":"04:22.505 ","End":"04:28.100","Text":"Those cytokines then are released into the blood system into the blood vessels,"},{"Start":"04:28.100 ","End":"04:31.340","Text":"and they move throughout the body and are picked up"},{"Start":"04:31.340 ","End":"04:35.005","Text":"or sensed in the hypothalamus of the brain."},{"Start":"04:35.005 ","End":"04:41.900","Text":"The brain then, in response to the cytokines, produces prostaglandins."},{"Start":"04:41.900 ","End":"04:51.635","Text":"Prostaglandins then are recognized by the thermocenter that is regulating temperature,"},{"Start":"04:51.635 ","End":"04:55.400","Text":"and we get a reset of"},{"Start":"04:55.400 ","End":"05:00.635","Text":"the thermostats in the body and produces a higher temperature, fever."},{"Start":"05:00.635 ","End":"05:07.190","Text":"The reason evidentially the body does this is because the pathogens that came into"},{"Start":"05:07.190 ","End":"05:13.370","Text":"the body in the first place are probably best set to work at 37 degrees."},{"Start":"05:13.370 ","End":"05:15.740","Text":"The body, therefore, raises the temperature,"},{"Start":"05:15.740 ","End":"05:18.680","Text":"and those pathogens don\u0027t work as well."},{"Start":"05:18.680 ","End":"05:20.600","Text":"Let\u0027s review this a little bit."},{"Start":"05:20.600 ","End":"05:25.443","Text":"These pyrogens act on the hypothalamic thermoregulatory center,"},{"Start":"05:25.443 ","End":"05:28.455","Text":"which is in the brain, the hypothalamus."},{"Start":"05:28.455 ","End":"05:33.170","Text":"Those pyrogens include interleukin-1,"},{"Start":"05:33.170 ","End":"05:37.970","Text":"and TNF-Alpha, and another 1 is IL-6."},{"Start":"05:37.970 ","End":"05:44.105","Text":"They reset the thermostat in order to fight the pathogens."},{"Start":"05:44.105 ","End":"05:45.935","Text":"In the next video,"},{"Start":"05:45.935 ","End":"05:51.500","Text":"we\u0027ll begin to look at what the response is to controlling or"},{"Start":"05:51.500 ","End":"05:59.040","Text":"regulating body temperature other than just raising the temperature with fever."}],"ID":27326},{"Watched":false,"Name":"Thermoregulation by Dissipation","Duration":"6m 34s","ChapterTopicVideoID":26398,"CourseChapterTopicPlaylistID":255407,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:07.350","Text":"Now let\u0027s continue our discussion of heat conservation and dissipation and talk about how"},{"Start":"00:07.350 ","End":"00:11.010","Text":"the body changes the dissipation or"},{"Start":"00:11.010 ","End":"00:16.320","Text":"conserves heat by changing the size of the blood vessels."},{"Start":"00:16.320 ","End":"00:22.815","Text":"Endotherms, that is again animals whose body temperature is regulated,"},{"Start":"00:22.815 ","End":"00:26.445","Text":"use their circulatory systems to help maintain body temperature."},{"Start":"00:26.445 ","End":"00:29.265","Text":"They do this 2 different ways,"},{"Start":"00:29.265 ","End":"00:34.035","Text":"either by vasodilation or vasoconstriction."},{"Start":"00:34.035 ","End":"00:36.690","Text":"That is, they dilate their blood vessels,"},{"Start":"00:36.690 ","End":"00:38.385","Text":"make them wider,"},{"Start":"00:38.385 ","End":"00:44.570","Text":"that increases the blood flow in the skin and facilitates heat loss."},{"Start":"00:44.570 ","End":"00:46.205","Text":"You can see that over here."},{"Start":"00:46.205 ","End":"00:49.310","Text":"Capillaries dilate near the skin surface and,"},{"Start":"00:49.310 ","End":"00:54.155","Text":"therefore, more heat can leave, cooling the blood."},{"Start":"00:54.155 ","End":"00:57.380","Text":"Another possibility is vasoconstriction."},{"Start":"00:57.380 ","End":"01:02.710","Text":"That is, blood flow in the skin decreases and that lowers the heat."},{"Start":"01:02.710 ","End":"01:04.130","Text":"That\u0027s what we can see here."},{"Start":"01:04.130 ","End":"01:06.950","Text":"If the blood vessel is constricted,"},{"Start":"01:06.950 ","End":"01:10.955","Text":"it doesn\u0027t allow so much blood to get near the surface of the skin,"},{"Start":"01:10.955 ","End":"01:14.750","Text":"then less heat is removed."},{"Start":"01:14.750 ","End":"01:18.859","Text":"There are other possibilities of sweat that are shown here,"},{"Start":"01:18.859 ","End":"01:21.860","Text":"and we\u0027ll discuss them a little bit later."},{"Start":"01:21.860 ","End":"01:23.420","Text":"Now, in addition to that,"},{"Start":"01:23.420 ","End":"01:30.995","Text":"another mechanism for heat exchange is countercurrent heat exchange. What is that?"},{"Start":"01:30.995 ","End":"01:34.370","Text":"That is the transfer of heat between fluids that are flowing"},{"Start":"01:34.370 ","End":"01:38.065","Text":"in opposite directions inside the body."},{"Start":"01:38.065 ","End":"01:39.500","Text":"If we think, for instance,"},{"Start":"01:39.500 ","End":"01:41.465","Text":"about whales, or dolphins,"},{"Start":"01:41.465 ","End":"01:44.720","Text":"or something like that that have a circulatory system,"},{"Start":"01:44.720 ","End":"01:47.555","Text":"and they have a very large heat sink around them,"},{"Start":"01:47.555 ","End":"01:49.003","Text":"that is the water,"},{"Start":"01:49.003 ","End":"01:54.260","Text":"then they can reduce their temperature or increase their temperature by changing"},{"Start":"01:54.260 ","End":"02:00.540","Text":"the width of their veins and arteries that are inside their flippers."},{"Start":"02:00.540 ","End":"02:05.945","Text":"This prevents the cold venous blood from cooling too much,"},{"Start":"02:05.945 ","End":"02:12.635","Text":"the veins that are on the outside that might cool the heart or other organs too much,"},{"Start":"02:12.635 ","End":"02:15.680","Text":"and it can be shut down,"},{"Start":"02:15.680 ","End":"02:17.360","Text":"this whole heat exchange,"},{"Start":"02:17.360 ","End":"02:22.295","Text":"in some animals to prevent overheating of the internal organs."},{"Start":"02:22.295 ","End":"02:26.510","Text":"Now we can also see that in some organisms,"},{"Start":"02:26.510 ","End":"02:27.590","Text":"like an elephant,"},{"Start":"02:27.590 ","End":"02:30.440","Text":"for instance, that have very large ears,"},{"Start":"02:30.440 ","End":"02:34.640","Text":"and they have large veins with a lot of blood that goes through the ears,"},{"Start":"02:34.640 ","End":"02:38.360","Text":"they can exchange heat to the outside"},{"Start":"02:38.360 ","End":"02:43.355","Text":"and that can help them cool themselves when they need to."},{"Start":"02:43.355 ","End":"02:48.080","Text":"Now let\u0027s look at the insulation aspect of"},{"Start":"02:48.080 ","End":"02:54.145","Text":"things and the production of heat inside fat cells."},{"Start":"02:54.145 ","End":"02:57.665","Text":"You\u0027ll remember that we have white fat cells"},{"Start":"02:57.665 ","End":"03:01.790","Text":"and we have brown fat cells that we discussed early."},{"Start":"03:01.790 ","End":"03:05.615","Text":"But actually there are brown fat cells that have"},{"Start":"03:05.615 ","End":"03:12.315","Text":"a bit fewer mitochondria that we might call beige fat cells because of their color."},{"Start":"03:12.315 ","End":"03:16.970","Text":"So we define them as beige and brown adipose tissue, that cells,"},{"Start":"03:16.970 ","End":"03:20.000","Text":"and they contain large numbers of mitochondria,"},{"Start":"03:20.000 ","End":"03:23.210","Text":"and that\u0027s what gives the tissue the color."},{"Start":"03:23.210 ","End":"03:29.605","Text":"They use fat burning to create heat without shivering."},{"Start":"03:29.605 ","End":"03:31.640","Text":"1 of the ways that we can increase heat,"},{"Start":"03:31.640 ","End":"03:32.945","Text":"as we mentioned earlier,"},{"Start":"03:32.945 ","End":"03:37.630","Text":"is to shiver, but we can also create heat without shivering,"},{"Start":"03:37.630 ","End":"03:42.457","Text":"and this is called non-shivering thermogenesis, or NST,"},{"Start":"03:42.457 ","End":"03:45.440","Text":"and that\u0027s found in infants and many mammals,"},{"Start":"03:45.440 ","End":"03:50.820","Text":"including humans and adult mammals that also hibernate."},{"Start":"03:50.820 ","End":"03:54.260","Text":"So let\u0027s look at this NST in a little bit more detail."},{"Start":"03:54.260 ","End":"03:55.610","Text":"In the brown fat,"},{"Start":"03:55.610 ","End":"04:00.980","Text":"the NST is actually the oxidative phosphorylation of the mitochondria,"},{"Start":"04:00.980 ","End":"04:02.690","Text":"but it\u0027s uncoupled,"},{"Start":"04:02.690 ","End":"04:06.035","Text":"that is, it produces almost no ATP."},{"Start":"04:06.035 ","End":"04:09.730","Text":"Instead, what it does is it produces heat."},{"Start":"04:09.730 ","End":"04:13.070","Text":"So almost all the released energy from"},{"Start":"04:13.070 ","End":"04:19.115","Text":"the oxidative phosphorylation is released as heat to heat the body,"},{"Start":"04:19.115 ","End":"04:21.930","Text":"and it\u0027s activated by stimulation, again,"},{"Start":"04:21.930 ","End":"04:27.965","Text":"of sympathetic nerves from the hypothalamus, that is,"},{"Start":"04:27.965 ","End":"04:32.360","Text":"remember the sensor or the main thermostat that"},{"Start":"04:32.360 ","End":"04:37.220","Text":"we have and that is in response then to cold weather."},{"Start":"04:37.220 ","End":"04:40.760","Text":"Ectotherms, and sometimes even endotherms,"},{"Start":"04:40.760 ","End":"04:44.800","Text":"can also change their behavior for thermoregulation."},{"Start":"04:44.800 ","End":"04:47.090","Text":"So they\u0027ll change their behavior."},{"Start":"04:47.090 ","End":"04:49.090","Text":"Let\u0027s see some examples of that."},{"Start":"04:49.090 ","End":"04:52.460","Text":"For instance, when some organisms are cold,"},{"Start":"04:52.460 ","End":"04:56.690","Text":"even insects, they\u0027ll seek warmer places to go."},{"Start":"04:56.690 ","End":"04:58.007","Text":"So their behaviors change."},{"Start":"04:58.007 ","End":"04:59.570","Text":"They move into the sun,"},{"Start":"04:59.570 ","End":"05:02.885","Text":"or they can orient themselves toward heat sources."},{"Start":"05:02.885 ","End":"05:05.330","Text":"Here\u0027s an elephant that\u0027s doing the opposite."},{"Start":"05:05.330 ","End":"05:07.880","Text":"It\u0027s cooling itself in water."},{"Start":"05:07.880 ","End":"05:12.845","Text":"They can move to cooler areas or change their orientation vis-a-vis the sun."},{"Start":"05:12.845 ","End":"05:14.798","Text":"Again, insects, for instance,"},{"Start":"05:14.798 ","End":"05:17.780","Text":"bees can use group activity."},{"Start":"05:17.780 ","End":"05:24.380","Text":"This very active hive and"},{"Start":"05:24.380 ","End":"05:28.325","Text":"the close concentration of the bees inside the hive"},{"Start":"05:28.325 ","End":"05:32.705","Text":"can actually raise the temperature inside the hive."},{"Start":"05:32.705 ","End":"05:39.185","Text":"Many animals can lose heat through evaporation of water from their skin."},{"Start":"05:39.185 ","End":"05:43.865","Text":"That would be sweating, for instance, perspiration."},{"Start":"05:43.865 ","End":"05:45.844","Text":"So the skin is moistened,"},{"Start":"05:45.844 ","End":"05:49.310","Text":"and then it evaporates to cool down the skin."},{"Start":"05:49.310 ","End":"05:50.630","Text":"You can see this, for instance,"},{"Start":"05:50.630 ","End":"05:52.533","Text":"this horse over here is wet."},{"Start":"05:52.533 ","End":"05:56.075","Text":"It\u0027s sweating. In humans,"},{"Start":"05:56.075 ","End":"05:58.759","Text":"the sweat rate can be quite substantial."},{"Start":"05:58.759 ","End":"06:03.290","Text":"We can lose between 2 and 4 liters an hour. That\u0027s a lot."},{"Start":"06:03.290 ","End":"06:06.620","Text":"That\u0027s an important reason that when the weather is very hot,"},{"Start":"06:06.620 ","End":"06:12.455","Text":"we must drink very large amounts."},{"Start":"06:12.455 ","End":"06:17.735","Text":"Other animals may lose water,"},{"Start":"06:17.735 ","End":"06:20.090","Text":"evaporate that water through their tongues, like dogs,"},{"Start":"06:20.090 ","End":"06:23.275","Text":"we know, for instance, will pant."},{"Start":"06:23.275 ","End":"06:26.930","Text":"We also see birds sometimes that, in hot weather,"},{"Start":"06:26.930 ","End":"06:33.810","Text":"will have their beaks open so that they can evaporate water from their systems."}],"ID":27325}],"Thumbnail":null,"ID":255407},{"Name":"Exercises","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Exercise 1","Duration":"1m 3s","ChapterTopicVideoID":26405,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.000","Text":"Which type of animal maintains a constant internal body temperature?"},{"Start":"00:06.000 ","End":"00:08.880","Text":"Endoderm."},{"Start":"00:08.880 ","End":"00:13.350","Text":"Endo means inside, ecto, outside."},{"Start":"00:13.350 ","End":"00:17.760","Text":"Sorry, it was an endotherm."},{"Start":"00:17.760 ","End":"00:20.664","Text":"Therm, temperature."},{"Start":"00:20.664 ","End":"00:24.480","Text":"Ectotherm, and 2 other things including mesoderm."},{"Start":"00:24.480 ","End":"00:26.430","Text":"Well, it\u0027s got to be 1 of these 2,"},{"Start":"00:26.430 ","End":"00:28.515","Text":"either a or b."},{"Start":"00:28.515 ","End":"00:33.810","Text":"Well, it\u0027s not b because ecto is outside."},{"Start":"00:33.810 ","End":"00:37.715","Text":"It\u0027s got to be an endoderm,"},{"Start":"00:37.715 ","End":"00:44.570","Text":"which when the ambient temperature changes,"},{"Start":"00:44.570 ","End":"00:46.467","Text":"it goes up or down,"},{"Start":"00:46.467 ","End":"00:50.975","Text":"the temperature inside the internal body temperature"},{"Start":"00:50.975 ","End":"00:55.055","Text":"stays about the same as you can see here with this bobcat,"},{"Start":"00:55.055 ","End":"00:57.545","Text":"as opposed to a snake,"},{"Start":"00:57.545 ","End":"01:00.425","Text":"which is an ectotherm."},{"Start":"01:00.425 ","End":"01:03.300","Text":"Our answer then is endotherm."}],"ID":27304},{"Watched":false,"Name":"Exercise 2","Duration":"1m 2s","ChapterTopicVideoID":26406,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:09.029","Text":"The symmetry found in animals that move swiftly is radial,"},{"Start":"00:09.029 ","End":"00:13.590","Text":"bilateral, sequential, or interrupted."},{"Start":"00:13.590 ","End":"00:15.610","Text":"Well, it\u0027s certainly not going to be radial,"},{"Start":"00:15.610 ","End":"00:18.945","Text":"it has to do with things that go in a circle."},{"Start":"00:18.945 ","End":"00:22.595","Text":"Sequential, one after the other, interrupted."},{"Start":"00:22.595 ","End":"00:24.320","Text":"No, it\u0027s going to be bilateral,"},{"Start":"00:24.320 ","End":"00:30.245","Text":"remember this picture here of bilateral symmetry in which you have"},{"Start":"00:30.245 ","End":"00:37.010","Text":"a division between the ventral and dorsal side of the animal,"},{"Start":"00:37.010 ","End":"00:42.790","Text":"which means that the front legs and the back legs are different from one another,"},{"Start":"00:42.790 ","End":"00:47.230","Text":"because the symmetry is bilateral."},{"Start":"00:47.230 ","End":"00:49.850","Text":"It\u0027s a plane cut from front-to-back,"},{"Start":"00:49.850 ","End":"00:54.170","Text":"that separates an animal into definite right and left sides, and this,"},{"Start":"00:54.170 ","End":"00:57.685","Text":"remember enables a high level of mobility,"},{"Start":"00:57.685 ","End":"01:02.880","Text":"so that to move swiftly. That\u0027s our answer."}],"ID":27305},{"Watched":false,"Name":"Exercise 3","Duration":"57s","ChapterTopicVideoID":26407,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.940","Text":"What term describes the condition of a desert mouse that lowers"},{"Start":"00:05.940 ","End":"00:11.865","Text":"its metabolic rate and sleeps during the hot day?"},{"Start":"00:11.865 ","End":"00:15.000","Text":"Is it turgid, hibernation,"},{"Start":"00:15.000 ","End":"00:19.200","Text":"estivation, or normal sleep pattern?"},{"Start":"00:19.200 ","End":"00:21.870","Text":"Well, turgid means swollen,"},{"Start":"00:21.870 ","End":"00:23.505","Text":"it can\u0027t be that."},{"Start":"00:23.505 ","End":"00:26.970","Text":"Is it hibernation maybe or estivation?"},{"Start":"00:26.970 ","End":"00:28.410","Text":"Certainly not normal."},{"Start":"00:28.410 ","End":"00:31.280","Text":"Well, we said it\u0027s not turgid."},{"Start":"00:31.280 ","End":"00:32.540","Text":"It\u0027s not hibernation."},{"Start":"00:32.540 ","End":"00:34.100","Text":"That\u0027s what a bear does in the winter."},{"Start":"00:34.100 ","End":"00:38.170","Text":"That\u0027s not what a desert mouse does when it makes things slower."},{"Start":"00:38.170 ","End":"00:41.240","Text":"Estivation is torpor in"},{"Start":"00:41.240 ","End":"00:44.690","Text":"the summer months when the temperatures are high and the water is scarce."},{"Start":"00:44.690 ","End":"00:48.140","Text":"Yes, that\u0027s when this mouse will"},{"Start":"00:48.140 ","End":"00:52.190","Text":"just lower its temperature and sleep just during the hot day,"},{"Start":"00:52.190 ","End":"00:53.735","Text":"not during a season."},{"Start":"00:53.735 ","End":"00:57.540","Text":"Our answer then is estivation."}],"ID":27306},{"Watched":false,"Name":"Exercise 4","Duration":"46s","ChapterTopicVideoID":26408,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:07.920","Text":"A plane that divides an animal into equal right and left portions is?"},{"Start":"00:07.920 ","End":"00:09.780","Text":"Is it a diagonal,"},{"Start":"00:09.780 ","End":"00:13.470","Text":"midsagittal, coronal or transverse?"},{"Start":"00:13.470 ","End":"00:17.775","Text":"Well, let\u0027s remember the kinds of planes there can be."},{"Start":"00:17.775 ","End":"00:21.300","Text":"I don\u0027t think that it really could be diagonal."},{"Start":"00:21.300 ","End":"00:23.040","Text":"How about coronal?"},{"Start":"00:23.040 ","End":"00:26.505","Text":"That would be a round like a corona, a round something."},{"Start":"00:26.505 ","End":"00:28.560","Text":"Transverse, through it, not right."},{"Start":"00:28.560 ","End":"00:31.350","Text":"It must be midsagittal,"},{"Start":"00:31.350 ","End":"00:32.880","Text":"and indeed it is."},{"Start":"00:32.880 ","End":"00:37.520","Text":"Midsagittal plane divides the body exactly in the middle,"},{"Start":"00:37.520 ","End":"00:41.474","Text":"making 2 equal right and left halves."},{"Start":"00:41.474 ","End":"00:42.630","Text":"That\u0027s what we want."},{"Start":"00:42.630 ","End":"00:46.570","Text":"Answer then is midsagittal."}],"ID":27307},{"Watched":false,"Name":"Exercise 5","Duration":"41s","ChapterTopicVideoID":26409,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.835","Text":"The pleural cavity is a part of which cavity?"},{"Start":"00:05.835 ","End":"00:09.330","Text":"Dorsal cavity, thoracic cavity,"},{"Start":"00:09.330 ","End":"00:14.505","Text":"abdominal cavity, or pericardial cavity."},{"Start":"00:14.505 ","End":"00:16.470","Text":"Well, this is something we just have to know,"},{"Start":"00:16.470 ","End":"00:21.420","Text":"pleura has to do with our lungs."},{"Start":"00:21.420 ","End":"00:24.255","Text":"Let\u0027s see."},{"Start":"00:24.255 ","End":"00:27.135","Text":"Would the answer then be dorsal?"},{"Start":"00:27.135 ","End":"00:28.230","Text":"Not really, that\u0027s in the back."},{"Start":"00:28.230 ","End":"00:31.050","Text":"Abdominal? No. It\u0027s got to be thoracic."},{"Start":"00:31.050 ","End":"00:33.450","Text":"That\u0027s where our lungs are, right?"},{"Start":"00:33.450 ","End":"00:40.930","Text":"The thoracic cavity is where the pleural cavity is. So that\u0027s our answer."}],"ID":27308},{"Watched":false,"Name":"Exercise 6","Duration":"1m 48s","ChapterTopicVideoID":26410,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.050 ","End":"00:06.585","Text":"Which of the following statements about types of epithelial cells is false?"},{"Start":"00:06.585 ","End":"00:12.990","Text":"The answer here has to do with something with the type of epithelial cells."},{"Start":"00:12.990 ","End":"00:16.470","Text":"We\u0027re looking for the 1 that is false."},{"Start":"00:16.470 ","End":"00:19.710","Text":"We\u0027ve got columnar, cuboidal."},{"Start":"00:19.710 ","End":"00:25.305","Text":"Remember, pseudostratified ones and transitional epithelium."},{"Start":"00:25.305 ","End":"00:30.075","Text":"Well, we\u0027re asking here, which is false."},{"Start":"00:30.075 ","End":"00:35.465","Text":"Is it that simple columnar epithelial cells line the tissue of the lung?"},{"Start":"00:35.465 ","End":"00:37.790","Text":"Well, let\u0027s see, maybe."},{"Start":"00:37.790 ","End":"00:40.970","Text":"What about simple cuboidal epithelial cells"},{"Start":"00:40.970 ","End":"00:43.445","Text":"are involved in the filtering of blood in the kidney."},{"Start":"00:43.445 ","End":"00:45.229","Text":"Remember, in the kidney,"},{"Start":"00:45.229 ","End":"00:50.300","Text":"what we found was that there were in the tubes of the ducts,"},{"Start":"00:50.300 ","End":"00:56.380","Text":"there were simple and stratified cuboidal."},{"Start":"00:56.380 ","End":"01:01.250","Text":"It\u0027s not just the simple 1 involved in filtering the blood."},{"Start":"01:01.250 ","End":"01:02.675","Text":"These are the tubules."},{"Start":"01:02.675 ","End":"01:06.990","Text":"What about pseudostratified columnar epithelial occur in a single layer,"},{"Start":"01:06.990 ","End":"01:10.935","Text":"but the arrangement in the nuclei makes it appear that more than 1 layer is present."},{"Start":"01:10.935 ","End":"01:17.090","Text":"No, because the pseudostratified ones occur in multiple."},{"Start":"01:17.090 ","End":"01:18.980","Text":"Well, actually it\u0027s 1 layer,"},{"Start":"01:18.980 ","End":"01:21.760","Text":"but the arrangement in the nuclei make them appear 1 layer is present,"},{"Start":"01:21.760 ","End":"01:24.115","Text":"but is that false? No, it\u0027s true."},{"Start":"01:24.115 ","End":"01:28.850","Text":"Transitional epithelial change in thickness depending on how full the bladder is?"},{"Start":"01:28.850 ","End":"01:32.465","Text":"Well, yes, because multiple layers of epithelial cells which can"},{"Start":"01:32.465 ","End":"01:37.100","Text":"contract and expand in order to adapt the degree of distention like in the bladder?"},{"Start":"01:37.100 ","End":"01:41.330","Text":"Yes, that\u0027s true. The 1 that\u0027s got to be wrong then is the first 1,"},{"Start":"01:41.330 ","End":"01:45.170","Text":"simple columnar epithelial cells line the tissue of the lung."},{"Start":"01:45.170 ","End":"01:48.360","Text":"No, that is not true."}],"ID":27309},{"Watched":false,"Name":"Exercise 7","Duration":"40s","ChapterTopicVideoID":26411,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.385","Text":"Which type of epithelial cells is best adapted to aid in diffusion?"},{"Start":"00:05.385 ","End":"00:09.840","Text":"Squamous, cuboidal, columnar, transitional."},{"Start":"00:09.840 ","End":"00:11.460","Text":"Well, let\u0027s see."},{"Start":"00:11.460 ","End":"00:15.750","Text":"Let\u0027s remember that the different cell shapes that we discussed here,"},{"Start":"00:15.750 ","End":"00:19.080","Text":"yes, are found in different locations."},{"Start":"00:19.080 ","End":"00:22.575","Text":"What were we asked? We were asked about diffusion."},{"Start":"00:22.575 ","End":"00:27.075","Text":"Yes. Where is their diffusion among these things?"},{"Start":"00:27.075 ","End":"00:35.610","Text":"Well, there is certainly in the digestive tract and in the respiratory tract."},{"Start":"00:35.610 ","End":"00:40.570","Text":"Our best answer then would be columnar, C."}],"ID":27310},{"Watched":false,"Name":"Exercise 8","Duration":"23s","ChapterTopicVideoID":26412,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.040","Text":"Which type of epithelial cell is found in glands?"},{"Start":"00:05.040 ","End":"00:10.590","Text":"Well, again here are the different epithelial cells."},{"Start":"00:10.590 ","End":"00:13.800","Text":"Let\u0027s go straight down now to the answer cuboidal,"},{"Start":"00:13.800 ","End":"00:21.195","Text":"because cuboidal are the ones that are found primarily in glands and renal tubules,"},{"Start":"00:21.195 ","End":"00:24.040","Text":"so that is our answer."}],"ID":27311},{"Watched":false,"Name":"Exercise 9","Duration":"28s","ChapterTopicVideoID":26413,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.734","Text":"Which type of epithelial cell now is found in the urinary bladder?"},{"Start":"00:05.734 ","End":"00:07.995","Text":"Again, the 4 different types."},{"Start":"00:07.995 ","End":"00:10.900","Text":"It\u0027s going to be transitional, right?"},{"Start":"00:10.900 ","End":"00:13.410","Text":"Because, again, in our table,"},{"Start":"00:13.410 ","End":"00:17.760","Text":"we see that the location of the transitional ones are in the urinary bladder."},{"Start":"00:17.760 ","End":"00:20.685","Text":"Remember, it\u0027s these transitional cells"},{"Start":"00:20.685 ","End":"00:24.375","Text":"which feel the pressure when our bladder becomes full."},{"Start":"00:24.375 ","End":"00:28.780","Text":"So the transitional ones are in the urinary bladder."}],"ID":27312},{"Watched":false,"Name":"Exercise 10","Duration":"45s","ChapterTopicVideoID":26414,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.405","Text":"Which type of connective tissue has the most fibers?"},{"Start":"00:06.405 ","End":"00:09.810","Text":"Loose connective tissue, fibrous connective tissue,"},{"Start":"00:09.810 ","End":"00:12.030","Text":"cartilage, or bone?"},{"Start":"00:12.030 ","End":"00:14.760","Text":"Well, certainly not bone."},{"Start":"00:14.760 ","End":"00:17.640","Text":"Well, it\u0027s not going to be bone."},{"Start":"00:17.640 ","End":"00:20.010","Text":"Not loose connective tissue either."},{"Start":"00:20.010 ","End":"00:22.260","Text":"Not cartilage, it doesn\u0027t really have fibers,"},{"Start":"00:22.260 ","End":"00:23.550","Text":"of course, not bone."},{"Start":"00:23.550 ","End":"00:30.290","Text":"Remember, that dense fibrous connective tissue is found in tendons which attach to"},{"Start":"00:30.290 ","End":"00:33.200","Text":"the muscles and bones and ligaments and which connect the bones at"},{"Start":"00:33.200 ","End":"00:37.310","Text":"the joints and they are very dense,"},{"Start":"00:37.310 ","End":"00:42.135","Text":"and they have the most fibers because they have to be the strongest ones."},{"Start":"00:42.135 ","End":"00:45.540","Text":"Our answer is, fibrous connective tissue."}],"ID":27313},{"Watched":false,"Name":"Exercise 11","Duration":"24s","ChapterTopicVideoID":26415,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.955","Text":"Which type of connective tissue has 8 mineralized different matrix?"},{"Start":"00:05.955 ","End":"00:09.750","Text":"Mineralized, well, mineral like with calcium."},{"Start":"00:09.750 ","End":"00:13.800","Text":"Of these things, it must be bone."},{"Start":"00:13.800 ","End":"00:15.885","Text":"I would say it\u0027s got to be bone."},{"Start":"00:15.885 ","End":"00:17.220","Text":"Yes, indeed. It\u0027s bone."},{"Start":"00:17.220 ","End":"00:23.950","Text":"Bone is mineralized and forms the skeleton as we all know. The bone."}],"ID":27314},{"Watched":false,"Name":"Exercise 12","Duration":"1m 12s","ChapterTopicVideoID":26416,"CourseChapterTopicPlaylistID":255408,"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 cell found in bone that breaks it down is called what?"},{"Start":"00:06.180 ","End":"00:08.295","Text":"Osteoblast."},{"Start":"00:08.295 ","End":"00:14.550","Text":"I think osteoblast must be wrong because that is what builds up the bone."},{"Start":"00:14.550 ","End":"00:16.680","Text":"Osteocyte."},{"Start":"00:16.680 ","End":"00:17.820","Text":"That\u0027s the earlier one."},{"Start":"00:17.820 ","End":"00:21.240","Text":"How about an osteoclast or an osteon?"},{"Start":"00:21.240 ","End":"00:26.655","Text":"Well, remember that osteoclast"},{"Start":"00:26.655 ","End":"00:33.180","Text":"is what functions in resorption during the destruction of bone matrix."},{"Start":"00:33.180 ","End":"00:38.475","Text":"The destruction and it breaks it down for bone remodeling."},{"Start":"00:38.475 ","End":"00:42.030","Text":"Access to calcium is stored in the tissues."},{"Start":"00:42.030 ","End":"00:44.970","Text":"It\u0027s osteoclast is the answer."},{"Start":"00:44.970 ","End":"00:48.545","Text":"The osteoblast forms the bone tissue,"},{"Start":"00:48.545 ","End":"00:54.650","Text":"as we said, the osteocyte is the early bone cell."},{"Start":"00:54.650 ","End":"00:57.950","Text":"The osteon, if you remember,"},{"Start":"00:57.950 ","End":"01:04.325","Text":"are the little circles that form the structure,"},{"Start":"01:04.325 ","End":"01:06.995","Text":"the basic structure in the bones."},{"Start":"01:06.995 ","End":"01:11.670","Text":"So it\u0027s not that either, it\u0027s the osteoclast."}],"ID":27315},{"Watched":false,"Name":"Exercise 13","Duration":"52s","ChapterTopicVideoID":26417,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.250","Text":"The cell found in bone that makes the bone is called what?"},{"Start":"00:05.250 ","End":"00:07.140","Text":"Osteoblast, osteocyte,"},{"Start":"00:07.140 ","End":"00:09.330","Text":"osteoclasts, or osteon."},{"Start":"00:09.330 ","End":"00:13.050","Text":"Well, let\u0027s see if we can remember."},{"Start":"00:13.050 ","End":"00:19.625","Text":"Osteoblast maybe the answer because it\u0027s the early cell."},{"Start":"00:19.625 ","End":"00:22.990","Text":"It\u0027s the cell which then forms the bone,"},{"Start":"00:22.990 ","End":"00:24.160","Text":"so makes the bone."},{"Start":"00:24.160 ","End":"00:25.910","Text":"That\u0027s probably going to be our answer."},{"Start":"00:25.910 ","End":"00:31.100","Text":"Osteocyte, osteoclasts, remember osteon are the structures."},{"Start":"00:31.100 ","End":"00:35.015","Text":"Here\u0027s an osteon structure that makes the bone,"},{"Start":"00:35.015 ","End":"00:36.830","Text":"but it\u0027s not one cell,"},{"Start":"00:36.830 ","End":"00:38.900","Text":"it\u0027s made of different cells."},{"Start":"00:38.900 ","End":"00:39.920","Text":"So that\u0027s not the answer,"},{"Start":"00:39.920 ","End":"00:41.210","Text":"so we have to watch for that."},{"Start":"00:41.210 ","End":"00:45.125","Text":"The answer then is going to be the osteoblast."},{"Start":"00:45.125 ","End":"00:48.920","Text":"Yes, the osteoblasts are for making bone growth and remodeling."},{"Start":"00:48.920 ","End":"00:51.930","Text":"Here they are, individual cells."}],"ID":27316},{"Watched":false,"Name":"Exercise 14","Duration":"34s","ChapterTopicVideoID":26418,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.350","Text":"Plasma is the what?"},{"Start":"00:04.350 ","End":"00:07.005","Text":"Fibers in blood, matrix of blood?"},{"Start":"00:07.005 ","End":"00:09.345","Text":"Are there really fibers in blood?"},{"Start":"00:09.345 ","End":"00:12.435","Text":"Not so sure that really would do it."},{"Start":"00:12.435 ","End":"00:15.449","Text":"The cell that phagocytized bacteria?"},{"Start":"00:15.449 ","End":"00:17.460","Text":"That\u0027s a little bit strange."},{"Start":"00:17.460 ","End":"00:21.045","Text":"Cell fragments found in the tissue?"},{"Start":"00:21.045 ","End":"00:24.345","Text":"Well, not the fibers clearly."},{"Start":"00:24.345 ","End":"00:26.475","Text":"It\u0027s not a cell, the plasma."},{"Start":"00:26.475 ","End":"00:29.085","Text":"It\u0027s not a cell fragment, it\u0027s the matrix of blood."},{"Start":"00:29.085 ","End":"00:32.010","Text":"Where it\u0027s composed of blood cells and cell fragments."},{"Start":"00:32.010 ","End":"00:35.290","Text":"That\u0027s what the blood plasma is."}],"ID":27317},{"Watched":false,"Name":"Exercise 15","Duration":"25s","ChapterTopicVideoID":26419,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.000","Text":"The type of muscle cell under voluntary control is?"},{"Start":"00:06.000 ","End":"00:08.190","Text":"Voluntary control, let\u0027s see,"},{"Start":"00:08.190 ","End":"00:11.265","Text":"that\u0027s what we can control ourselves."},{"Start":"00:11.265 ","End":"00:14.805","Text":"Smooth, skeletal, cardiac, or visceral muscle?"},{"Start":"00:14.805 ","End":"00:17.070","Text":"Well, it\u0027s got to be skeletal muscle, right?"},{"Start":"00:17.070 ","End":"00:18.810","Text":"That\u0027s what\u0027s under our control."},{"Start":"00:18.810 ","End":"00:19.860","Text":"That was an easy one."},{"Start":"00:19.860 ","End":"00:25.510","Text":"Skeletal muscle is under voluntary somatic nervous system control."}],"ID":27318},{"Watched":false,"Name":"Exercise 16","Duration":"1m 2s","ChapterTopicVideoID":26400,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.330","Text":"The part of a neuron, nerve cells,"},{"Start":"00:03.330 ","End":"00:06.555","Text":"yes, that contains the nucleus, is what?"},{"Start":"00:06.555 ","End":"00:09.690","Text":"What part of the neuron contains the nucleus?"},{"Start":"00:09.690 ","End":"00:11.280","Text":"Cell body, dendrite,"},{"Start":"00:11.280 ","End":"00:13.620","Text":"axon, or a glial cell?"},{"Start":"00:13.620 ","End":"00:19.020","Text":"Well, let\u0027s remember what each of these pieces is."},{"Start":"00:19.020 ","End":"00:23.310","Text":"Note the dendrites or axon or the glial cell."},{"Start":"00:23.310 ","End":"00:29.115","Text":"Remember that dendrites are these branches that are at the edge."},{"Start":"00:29.115 ","End":"00:30.810","Text":"Then we see the nucleus here,"},{"Start":"00:30.810 ","End":"00:32.460","Text":"which is in the middle of the cell,"},{"Start":"00:32.460 ","End":"00:35.085","Text":"which is called the cell body."},{"Start":"00:35.085 ","End":"00:36.765","Text":"Yes, it\u0027s not the dendrites,"},{"Start":"00:36.765 ","End":"00:42.151","Text":"it\u0027s not the axon which is out here,"},{"Start":"00:42.151 ","End":"00:46.730","Text":"that connects a distant part with its dendrites from the cell body."},{"Start":"00:46.730 ","End":"00:48.620","Text":"It\u0027s not the glial cells either."},{"Start":"00:48.620 ","End":"00:56.315","Text":"These are the glial cells that cover the axon for providing it with insulation."},{"Start":"00:56.315 ","End":"00:58.340","Text":"It\u0027s got to be the cell body."},{"Start":"00:58.340 ","End":"01:01.980","Text":"That\u0027s where the nucleus is and that\u0027s our answer."}],"ID":27319},{"Watched":false,"Name":"Exercise 17","Duration":"1m 27s","ChapterTopicVideoID":26401,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.065","Text":"When faced with a sudden drop in environmental temperature,"},{"Start":"00:04.065 ","End":"00:06.525","Text":"an endothermic animal,"},{"Start":"00:06.525 ","End":"00:09.000","Text":"endothermic, what does that mean?"},{"Start":"00:09.000 ","End":"00:16.545","Text":"That means an animal that has its body temperature controlled on the inside."},{"Start":"00:16.545 ","End":"00:20.937","Text":"Endothermic, on the inside."},{"Start":"00:20.937 ","End":"00:22.410","Text":"What will happen?"},{"Start":"00:22.410 ","End":"00:27.530","Text":"Will the drop in temperature outside experience a drop in its body temperature?"},{"Start":"00:27.530 ","End":"00:31.970","Text":"Well, probably not because it\u0027s controlling its temperature inside."},{"Start":"00:31.970 ","End":"00:33.710","Text":"Wait to see if it goes lower?"},{"Start":"00:33.710 ","End":"00:35.690","Text":"No, it doesn\u0027t wait."},{"Start":"00:35.690 ","End":"00:38.390","Text":"There\u0027s a pretty quick response."},{"Start":"00:38.390 ","End":"00:41.930","Text":"Increased muscle activity to generate heat? We will return to this."},{"Start":"00:41.930 ","End":"00:46.195","Text":"Or add fur? Well, we don\u0027t add fur that quickly."},{"Start":"00:46.195 ","End":"00:49.820","Text":"Increasing muscle activity must be the answer."},{"Start":"00:49.820 ","End":"00:56.390","Text":"If you remember, the hypothalamic region of the brain has a shivering,"},{"Start":"00:56.390 ","End":"00:59.930","Text":"thermogenesis possibility, shivers. We shiver, right?"},{"Start":"00:59.930 ","End":"01:02.275","Text":"That\u0027s our muscles that are doing this."},{"Start":"01:02.275 ","End":"01:08.270","Text":"Skeletal muscle is controlled by the thermoregulatory center in the brain,"},{"Start":"01:08.270 ","End":"01:13.550","Text":"which causes us to shiver, to generate heat."},{"Start":"01:13.550 ","End":"01:16.070","Text":"We increase muscle activity to generate heat."},{"Start":"01:16.070 ","End":"01:17.450","Text":"That\u0027s one of the ways,"},{"Start":"01:17.450 ","End":"01:19.340","Text":"yes, there are other ways as well,"},{"Start":"01:19.340 ","End":"01:27.240","Text":"to generate heat and keep our body temperature constant in an endothermic animal."}],"ID":27320},{"Watched":false,"Name":"Exercise 18","Duration":"1m 7s","ChapterTopicVideoID":26402,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.845","Text":"Which is an example of negative feedback?"},{"Start":"00:04.845 ","End":"00:08.100","Text":"Is it\u0027s lowering the blood glucose after a meal,"},{"Start":"00:08.100 ","End":"00:09.920","Text":"blood clotting after an injury?"},{"Start":"00:09.920 ","End":"00:14.340","Text":"It\u0027s not that. Lactation during nursing? Not that."},{"Start":"00:14.340 ","End":"00:16.290","Text":"Uterine contractions during labor?"},{"Start":"00:16.290 ","End":"00:19.935","Text":"Clearly not that. Lowering of blood glucose after a meal."},{"Start":"00:19.935 ","End":"00:24.555","Text":"Remember of the various negative feedback mechanisms."},{"Start":"00:24.555 ","End":"00:30.050","Text":"Yes, we have the various examples including the glucose."},{"Start":"00:30.050 ","End":"00:32.855","Text":"Now what are the negative feedback mechanisms?"},{"Start":"00:32.855 ","End":"00:34.940","Text":"Homeostatic process."},{"Start":"00:34.940 ","End":"00:38.345","Text":"It\u0027s a process that changes direction of the stimulus."},{"Start":"00:38.345 ","End":"00:40.580","Text":"If we ate something;"},{"Start":"00:40.580 ","End":"00:42.845","Text":"glucose after a meal,"},{"Start":"00:42.845 ","End":"00:46.145","Text":"that would raise our glucose, we\u0027ve eaten something,"},{"Start":"00:46.145 ","End":"00:49.415","Text":"the sugar in our blood goes up and so"},{"Start":"00:49.415 ","End":"00:55.325","Text":"the homeostatic process makes the direction of the stimulus opposite."},{"Start":"00:55.325 ","End":"00:57.200","Text":"In other words, go down."},{"Start":"00:57.200 ","End":"01:02.330","Text":"Yes, so glucose is an example of a negative feedback mechanism."},{"Start":"01:02.330 ","End":"01:07.980","Text":"Lowering of blood glucose is this negative feedback mechanism."}],"ID":27321},{"Watched":false,"Name":"Exercise 19","Duration":"57s","ChapterTopicVideoID":26403,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:08.565","Text":"Which method of heat exchange occurs during direct contact between the source and animal?"},{"Start":"00:08.565 ","End":"00:10.559","Text":"Well, is it radiation,"},{"Start":"00:10.559 ","End":"00:13.380","Text":"evaporation, convection, or conduction?"},{"Start":"00:13.380 ","End":"00:16.995","Text":"We\u0027re talking here about direct contact."},{"Start":"00:16.995 ","End":"00:20.955","Text":"That\u0027s got to be conduction if it\u0027s direct."},{"Start":"00:20.955 ","End":"00:22.755","Text":"Indeed, if you remember,"},{"Start":"00:22.755 ","End":"00:24.480","Text":"if we have direct contact,"},{"Start":"00:24.480 ","End":"00:26.595","Text":"say between a rock and an iguana,"},{"Start":"00:26.595 ","End":"00:35.035","Text":"then the heat exchange is conduction going straight from the rock to the iguana."},{"Start":"00:35.035 ","End":"00:38.510","Text":"Evaporation would be when it\u0027s breathing,"},{"Start":"00:38.510 ","End":"00:41.000","Text":"it evaporates, and that\u0027s one and different way."},{"Start":"00:41.000 ","End":"00:43.450","Text":"There\u0027s radiation, the sun heating it up."},{"Start":"00:43.450 ","End":"00:47.600","Text":"Convection, could be that the air is passing by"},{"Start":"00:47.600 ","End":"00:51.890","Text":"and there\u0027s heat which is going off of the animal that way."},{"Start":"00:51.890 ","End":"00:57.539","Text":"But we were asked about direct contact, so that\u0027s conduction."}],"ID":27322},{"Watched":false,"Name":"Exercise 20","Duration":"26s","ChapterTopicVideoID":26404,"CourseChapterTopicPlaylistID":255408,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.380","Text":"The body\u0027s thermostat is located where?"},{"Start":"00:04.380 ","End":"00:07.620","Text":"In the homeostatic receptor, hypothalamus,"},{"Start":"00:07.620 ","End":"00:10.650","Text":"medulla, or vasodilation center?"},{"Start":"00:10.650 ","End":"00:13.080","Text":"Well, this is something just we have to know."},{"Start":"00:13.080 ","End":"00:16.620","Text":"It\u0027s in the hypothalamus of the brain."},{"Start":"00:16.620 ","End":"00:21.675","Text":"A part of the brain is where the body\u0027s thermostat is located."},{"Start":"00:21.675 ","End":"00:25.510","Text":"Here we can see, in the hypothalamus."}],"ID":27323}],"Thumbnail":null,"ID":255408}]

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