[{"Name":"Neurons and Glial Cells","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Structure of Nerves","Duration":"8m 26s","ChapterTopicVideoID":27854,"CourseChapterTopicPlaylistID":275100,"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":"Welcome back to our discussions about different systems in the body."},{"Start":"00:06.000 ","End":"00:10.620","Text":"Now, we\u0027re going to be discussing the nervous system in considerable detail."},{"Start":"00:10.620 ","End":"00:15.030","Text":"We\u0027ll start out by talking about neurons and glial cells."},{"Start":"00:15.030 ","End":"00:19.560","Text":"Of course, the neurons are going to be the cells which are going to be carrying"},{"Start":"00:19.560 ","End":"00:25.830","Text":"the information of the nerves and the glial cells are going to be protective cells,"},{"Start":"00:25.830 ","End":"00:31.635","Text":"as we\u0027ll see that they have various functions."},{"Start":"00:31.635 ","End":"00:34.235","Text":"First of all, the nervous system in general,"},{"Start":"00:34.235 ","End":"00:36.260","Text":"coordinates the organism\u0027s behavior and"},{"Start":"00:36.260 ","End":"00:39.590","Text":"transmits signals between different areas of the body."},{"Start":"00:39.590 ","End":"00:41.390","Text":"We\u0027re talking about signaling."},{"Start":"00:41.390 ","End":"00:47.390","Text":"There can be signaling within different parts of the body and there can be signaling,"},{"Start":"00:47.390 ","End":"00:51.200","Text":"of course, back and forth between various parts of the body."},{"Start":"00:51.200 ","End":"00:57.860","Text":"Let\u0027s say muscles or pain sensors and things of that sort back-and-forth to the brain."},{"Start":"00:57.860 ","End":"01:00.365","Text":"They could be to the eye to see and so on."},{"Start":"01:00.365 ","End":"01:02.320","Text":"To the mouth to taste."},{"Start":"01:02.320 ","End":"01:04.860","Text":"All of that is the nervous system."},{"Start":"01:04.860 ","End":"01:07.220","Text":"There are the signals which are transmitted,"},{"Start":"01:07.220 ","End":"01:10.580","Text":"of course, between the various parts."},{"Start":"01:10.580 ","End":"01:15.275","Text":"You\u0027re using the nervous system a lot right now,"},{"Start":"01:15.275 ","End":"01:18.635","Text":"the brain is interacting with all systems."},{"Start":"01:18.635 ","End":"01:20.720","Text":"You\u0027re watching this lesson now."},{"Start":"01:20.720 ","End":"01:24.955","Text":"The nerves control what you do and as well how you behave."},{"Start":"01:24.955 ","End":"01:29.615","Text":"You have a visual system which sees what\u0027s on the page."},{"Start":"01:29.615 ","End":"01:32.420","Text":"You have motor system, things that move things around,"},{"Start":"01:32.420 ","End":"01:34.940","Text":"for instance, turning your head around."},{"Start":"01:34.940 ","End":"01:40.130","Text":"There\u0027s a prefrontal cortex that\u0027s something that\u0027s in the front"},{"Start":"01:40.130 ","End":"01:44.690","Text":"of your brain that is not controlling anything in particular,"},{"Start":"01:44.690 ","End":"01:50.855","Text":"but there is an attention that it causes and so that other things will work together."},{"Start":"01:50.855 ","End":"01:52.414","Text":"Of course, your breathing,"},{"Start":"01:52.414 ","End":"01:53.870","Text":"body temperature is controlled."},{"Start":"01:53.870 ","End":"01:56.900","Text":"All those things, as we\u0027d seen in previous chapters,"},{"Start":"01:56.900 ","End":"01:59.300","Text":"are also influenced by the brain."},{"Start":"01:59.300 ","End":"02:02.600","Text":"The connections have to be,"},{"Start":"02:02.600 ","End":"02:05.270","Text":"or they can be through the nervous system."},{"Start":"02:05.270 ","End":"02:07.460","Text":"In this case, we\u0027re talking about the nervous system."},{"Start":"02:07.460 ","End":"02:13.070","Text":"Now let\u0027s look at different nervous systems in different organisms."},{"Start":"02:13.070 ","End":"02:15.470","Text":"Of course, we have,"},{"Start":"02:15.470 ","End":"02:18.275","Text":"we can start out with invertebrates."},{"Start":"02:18.275 ","End":"02:23.905","Text":"Invertebrates, which of course do not have a spinal cord."},{"Start":"02:23.905 ","End":"02:28.160","Text":"There are very simple organisms like hydra for instance."},{"Start":"02:28.160 ","End":"02:33.350","Text":"They have many neurons that are in some network and connection with one another."},{"Start":"02:33.350 ","End":"02:38.014","Text":"We\u0027ll see in a minute there are too many of them as compared with other organisms."},{"Start":"02:38.014 ","End":"02:42.680","Text":"They will contact epithelial muscular cells."},{"Start":"02:42.680 ","End":"02:46.880","Text":"A hydrous can move some of their tentacles, for instance,"},{"Start":"02:46.880 ","End":"02:52.925","Text":"in response to what\u0027s going on outside and that\u0027s mediated by these membranes."},{"Start":"02:52.925 ","End":"02:56.365","Text":"There\u0027s another organism called the Planaria."},{"Start":"02:56.365 ","End":"02:58.145","Text":"These, as you can see,"},{"Start":"02:58.145 ","End":"03:02.105","Text":"have like a ladder nervous system."},{"Start":"03:02.105 ","End":"03:07.340","Text":"They have a concentration of ganglia around the head."},{"Start":"03:07.340 ","End":"03:09.890","Text":"Something which is anterior ganglia,"},{"Start":"03:09.890 ","End":"03:15.330","Text":"something more like the brain or start of a brain."},{"Start":"03:15.330 ","End":"03:20.270","Text":"Of course then there are other organisms like annelids, arthropods, mollusks."},{"Start":"03:20.270 ","End":"03:22.670","Text":"Arthropods, for instance, are insects,"},{"Start":"03:22.670 ","End":"03:25.745","Text":"grasshoppers, and they do have a brain."},{"Start":"03:25.745 ","End":"03:28.310","Text":"There\u0027s a little brain, even in earthworms,"},{"Start":"03:28.310 ","End":"03:32.180","Text":"that will then control or control"},{"Start":"03:32.180 ","End":"03:36.260","Text":"the nerves that are a little bit further away in the body."},{"Start":"03:36.260 ","End":"03:42.440","Text":"Now what\u0027s interesting is that in each of these organisms in invertebrates,"},{"Start":"03:42.440 ","End":"03:46.925","Text":"the nervous system is often located ventrally."},{"Start":"03:46.925 ","End":"03:50.690","Text":"That means closer to the front of the organisms,"},{"Start":"03:50.690 ","End":"03:53.660","Text":"opposed to dorsally to the back."},{"Start":"03:53.660 ","End":"03:57.785","Text":"When we look at vertebrate nervous systems,"},{"Start":"03:57.785 ","End":"04:00.950","Text":"vertebrate nervous systems, first of all,"},{"Start":"04:00.950 ","End":"04:06.195","Text":"we will find that they are usually dorsal, not ventral."},{"Start":"04:06.195 ","End":"04:10.820","Text":"We can divide the vertebrate nervous system into 2 parts."},{"Start":"04:10.820 ","End":"04:16.340","Text":"Central nervous system, which you can see is centered in the brain and the spinal cord."},{"Start":"04:16.340 ","End":"04:22.280","Text":"Then there is the peripheral nervous system that does something different."},{"Start":"04:22.280 ","End":"04:25.820","Text":"As we just mentioned, this system,"},{"Start":"04:25.820 ","End":"04:28.760","Text":"the central nervous system primarily is located"},{"Start":"04:28.760 ","End":"04:32.390","Text":"dorsally in vertebrates and not ventrally."},{"Start":"04:32.390 ","End":"04:34.220","Text":"Now the central nervous system,"},{"Start":"04:34.220 ","End":"04:37.205","Text":"which is sometimes called the CNS,"},{"Start":"04:37.205 ","End":"04:39.350","Text":"is the brain and spinal cord."},{"Start":"04:39.350 ","End":"04:41.420","Text":"Whereas the peripheral nervous system,"},{"Start":"04:41.420 ","End":"04:44.740","Text":"which is usually called the PNS, yes,"},{"Start":"04:44.740 ","End":"04:49.430","Text":"contains all the various nerves that are all over the things,"},{"Start":"04:49.430 ","End":"04:51.560","Text":"all over the rest of the body."},{"Start":"04:51.560 ","End":"04:55.265","Text":"They gather information from sensors and conducted"},{"Start":"04:55.265 ","End":"04:59.705","Text":"back towards the central nervous system to effectors."},{"Start":"04:59.705 ","End":"05:04.745","Text":"Or they can also do it even without the central nervous system,"},{"Start":"05:04.745 ","End":"05:09.280","Text":"in the case for instance, of reflexes."},{"Start":"05:09.280 ","End":"05:13.340","Text":"Those lie outside the central nervous system."},{"Start":"05:13.340 ","End":"05:17.965","Text":"Now let\u0027s look at specific functions of the nervous system."},{"Start":"05:17.965 ","End":"05:24.635","Text":"As you can see, there can be receptors like our eyes, which sees something."},{"Start":"05:24.635 ","End":"05:28.020","Text":"That will mean that we\u0027ll"},{"Start":"05:28.020 ","End":"05:31.985","Text":"see something and the response to that will be to move a muscle."},{"Start":"05:31.985 ","End":"05:33.290","Text":"How does that happen?"},{"Start":"05:33.290 ","End":"05:35.540","Text":"Well, there are nerves."},{"Start":"05:35.540 ","End":"05:40.310","Text":"There\u0027s something in the nervous system which will connect the receptor with the brain."},{"Start":"05:40.310 ","End":"05:46.355","Text":"The brain will make some sense of what we\u0027ve seen and then it will send"},{"Start":"05:46.355 ","End":"05:48.860","Text":"integrated signal back out to"},{"Start":"05:48.860 ","End":"05:54.230","Text":"the appropriate muscles so that we get an appropriate response."},{"Start":"05:54.230 ","End":"05:59.120","Text":"There is a receiving sensory inputs and then there\u0027s integration."},{"Start":"05:59.120 ","End":"06:02.270","Text":"Then finally, there\u0027s motor output."},{"Start":"06:02.270 ","End":"06:07.670","Text":"Now, let\u0027s look a little bit more carefully at these nerves and what\u0027s in them."},{"Start":"06:07.670 ","End":"06:17.485","Text":"The composition of the nerve tissue is composed of neurons and nerves."},{"Start":"06:17.485 ","End":"06:22.400","Text":"What\u0027s the difference? Well, the nerve is going to be"},{"Start":"06:22.400 ","End":"06:27.140","Text":"the entire bundle, really of neurons."},{"Start":"06:27.140 ","End":"06:32.630","Text":"We\u0027ll have many neurons that are inside 1 nerve and that are"},{"Start":"06:32.630 ","End":"06:35.840","Text":"acting together as they are bundled together and"},{"Start":"06:35.840 ","End":"06:39.635","Text":"those will be in the peripheral nervous system primarily."},{"Start":"06:39.635 ","End":"06:45.660","Text":"The neurons themselves are the cells that receive and transmit signals."},{"Start":"06:45.660 ","End":"06:47.825","Text":"Whether they be chemical or electrical,"},{"Start":"06:47.825 ","End":"06:49.610","Text":"that we\u0027ll see in a minute."},{"Start":"06:49.610 ","End":"06:54.620","Text":"Now, let\u0027s look at what the nerve tissue is composed of."},{"Start":"06:54.620 ","End":"06:56.645","Text":"In the previous slide,"},{"Start":"06:56.645 ","End":"07:02.600","Text":"we\u0027ve seen that in addition to the nerves themselves and neurons, I beg your pardon."},{"Start":"07:02.600 ","End":"07:04.370","Text":"In addition to the neurons themselves,"},{"Start":"07:04.370 ","End":"07:06.110","Text":"there is some connective tissue here."},{"Start":"07:06.110 ","End":"07:11.180","Text":"The neurons, there is some connective tissue and there are veins and arteries in order to"},{"Start":"07:11.180 ","End":"07:16.435","Text":"keep everything alive with nutrients and exchange of gases."},{"Start":"07:16.435 ","End":"07:19.340","Text":"In addition to that, if you look at the axons,"},{"Start":"07:19.340 ","End":"07:23.525","Text":"that is the internal part of the neurons,"},{"Start":"07:23.525 ","End":"07:26.960","Text":"then we\u0027ll see that there is something called a myelin sheath,"},{"Start":"07:26.960 ","End":"07:28.895","Text":"there is an insulator if you like,"},{"Start":"07:28.895 ","End":"07:34.720","Text":"around the outside and we\u0027ll see in a minute what that looks like."},{"Start":"07:34.720 ","End":"07:38.660","Text":"Here\u0027s what the nerve tissue itself looks like."},{"Start":"07:38.660 ","End":"07:41.165","Text":"We\u0027ve had the neurons as we\u0027ve discussed,"},{"Start":"07:41.165 ","End":"07:44.630","Text":"yes, that compose the nerve."},{"Start":"07:44.630 ","End":"07:47.675","Text":"Around them are these glia."},{"Start":"07:47.675 ","End":"07:52.040","Text":"These are cells that are around the outside"},{"Start":"07:52.040 ","End":"07:57.970","Text":"of the axons and they provide various support functions."},{"Start":"07:57.970 ","End":"08:01.130","Text":"They can also, it turns out,"},{"Start":"08:01.130 ","End":"08:03.500","Text":"have some of the signaling functions."},{"Start":"08:03.500 ","End":"08:04.880","Text":"But for the most part,"},{"Start":"08:04.880 ","End":"08:11.035","Text":"they will either protect or they will serve as insulators for the neurons."},{"Start":"08:11.035 ","End":"08:16.820","Text":"There\u0027s quite a great diversity of both neurons and the different types,"},{"Start":"08:16.820 ","End":"08:20.800","Text":"different shapes of neurons and of the glia."},{"Start":"08:20.800 ","End":"08:26.370","Text":"We\u0027ll see more of that in the following video."}],"ID":29042},{"Watched":false,"Name":"Neuron and glia structure","Duration":"9m 50s","ChapterTopicVideoID":27853,"CourseChapterTopicPlaylistID":275100,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:07.260","Text":"I\u0027m glad you\u0027re back to our discussion of neurons and glial cells that are in nerves."},{"Start":"00:07.260 ","End":"00:12.060","Text":"As you remember, we discussed the composition of the nerve tissue of containing"},{"Start":"00:12.060 ","End":"00:17.770","Text":"neurons and glia and the glia were the cells that are on the outside of the neurons."},{"Start":"00:17.770 ","End":"00:20.580","Text":"We said that there is a great diversity in"},{"Start":"00:20.580 ","End":"00:24.255","Text":"the different types of neurons and glial cells."},{"Start":"00:24.255 ","End":"00:26.775","Text":"Let\u0027s look a little bit of that diversity."},{"Start":"00:26.775 ","End":"00:31.820","Text":"You can see that there are different kinds of neurons, bipolar,"},{"Start":"00:31.820 ","End":"00:35.210","Text":"unipolar, multipolar neurons,"},{"Start":"00:35.210 ","End":"00:36.950","Text":"and they have different shapes."},{"Start":"00:36.950 ","End":"00:39.680","Text":"We\u0027ll discuss that a little bit later."},{"Start":"00:39.680 ","End":"00:41.090","Text":"In addition to that,"},{"Start":"00:41.090 ","End":"00:43.490","Text":"besides the number of shapes,"},{"Start":"00:43.490 ","End":"00:47.000","Text":"there are also large differences in the numbers"},{"Start":"00:47.000 ","End":"00:51.315","Text":"of these neurons altogether in various organisms."},{"Start":"00:51.315 ","End":"00:55.055","Text":"Whereas the fly has about 100,000 neurons in it,"},{"Start":"00:55.055 ","End":"01:01.925","Text":"humans have 86,000,000,000 neurons with other organisms someplace in the middle."},{"Start":"01:01.925 ","End":"01:03.590","Text":"Well, maybe that doesn\u0027t surprise you."},{"Start":"01:03.590 ","End":"01:06.065","Text":"Of course, we think an awful lot better"},{"Start":"01:06.065 ","End":"01:08.930","Text":"than a laboratory fly and we\u0027re a lot more complicated."},{"Start":"01:08.930 ","End":"01:15.800","Text":"In fact, that really is reflected in the number of neurons that we have."},{"Start":"01:15.800 ","End":"01:18.770","Text":"Of course, on a basic level,"},{"Start":"01:18.770 ","End":"01:22.580","Text":"the same behaviors occur in all these various organisms."},{"Start":"01:22.580 ","End":"01:27.200","Text":"Basic reflexes and various complicated behaviors and it\u0027s very"},{"Start":"01:27.200 ","End":"01:33.340","Text":"interesting that the nerves in the different systems work very much in the same way."},{"Start":"01:33.340 ","End":"01:37.145","Text":"Now let\u0027s look at how that works."},{"Start":"01:37.145 ","End":"01:43.640","Text":"The general structure of the neurons is that there\u0027s a cell body, yes,"},{"Start":"01:43.640 ","End":"01:51.350","Text":"and there is a dendrite along which the signal will travel."},{"Start":"01:51.350 ","End":"01:58.440","Text":"Then it has to interact with another kind of cell or another neuron possibly."},{"Start":"01:58.440 ","End":"02:06.505","Text":"That interaction can be either electrical or it can be chemical."},{"Start":"02:06.505 ","End":"02:11.315","Text":"If it\u0027s electrical, that\u0027s more like the wires that we\u0027re used to"},{"Start":"02:11.315 ","End":"02:14.630","Text":"different dendrites will touch each"},{"Start":"02:14.630 ","End":"02:18.605","Text":"other and the signal actually will pass from one to the other."},{"Start":"02:18.605 ","End":"02:23.945","Text":"The other possibility is that they will interact in a chemical way."},{"Start":"02:23.945 ","End":"02:25.340","Text":"This is what you can see here."},{"Start":"02:25.340 ","End":"02:29.300","Text":"You can see the something called a synapse and we\u0027ll discuss that"},{"Start":"02:29.300 ","End":"02:33.440","Text":"a bit later in which there is a chemical movement,"},{"Start":"02:33.440 ","End":"02:40.190","Text":"a neurotransmitter, which moves from 1 cell to the other."},{"Start":"02:40.190 ","End":"02:43.415","Text":"Now, if we want to understand this better,"},{"Start":"02:43.415 ","End":"02:47.990","Text":"we have to look at the different parts of a neuron in greater detail."},{"Start":"02:47.990 ","End":"02:52.175","Text":"There is the main part of the cell called the cell body,"},{"Start":"02:52.175 ","End":"02:54.470","Text":"which contains the nucleus and the organelles,"},{"Start":"02:54.470 ","End":"02:59.250","Text":"just like any other kind of cell that we\u0027re familiar with."},{"Start":"02:59.250 ","End":"03:01.310","Text":"Again, that\u0027s called the cell body."},{"Start":"03:01.310 ","End":"03:02.825","Text":"But as you can see,"},{"Start":"03:02.825 ","End":"03:04.655","Text":"and as we\u0027ve noticed before,"},{"Start":"03:04.655 ","End":"03:08.435","Text":"the shape of these cells is quite different and"},{"Start":"03:08.435 ","End":"03:12.455","Text":"that shape is reflected mostly in these dendrites,"},{"Start":"03:12.455 ","End":"03:15.920","Text":"which are the branched extensions that receive signals"},{"Start":"03:15.920 ","End":"03:20.360","Text":"from other neurons or from the receptors that they\u0027re connected to."},{"Start":"03:20.360 ","End":"03:22.040","Text":"In addition to that,"},{"Start":"03:22.040 ","End":"03:25.130","Text":"we have things that are called axons."},{"Start":"03:25.130 ","End":"03:28.670","Text":"Now the axons are typically confused with the dendrites."},{"Start":"03:28.670 ","End":"03:32.360","Text":"We can have several different dendrites that are extending"},{"Start":"03:32.360 ","End":"03:36.420","Text":"from the cell body that don\u0027t really not"},{"Start":"03:36.420 ","End":"03:39.800","Text":"involved in the long nerve impulse or in"},{"Start":"03:39.800 ","End":"03:44.855","Text":"the long signal which goes from 1 cell to the other that goes through the axon."},{"Start":"03:44.855 ","End":"03:48.965","Text":"It\u0027s the long extension of these dendrites."},{"Start":"03:48.965 ","End":"03:53.230","Text":"In addition, we have something called an axon hillock."},{"Start":"03:53.230 ","End":"03:56.240","Text":"That\u0027s not shown here in this picture,"},{"Start":"03:56.240 ","End":"03:59.885","Text":"but you can have many different signals that come in"},{"Start":"03:59.885 ","End":"04:05.045","Text":"various places and they then have to get integrated."},{"Start":"04:05.045 ","End":"04:08.990","Text":"The signals have to get integrated from these different synapses,"},{"Start":"04:08.990 ","End":"04:17.120","Text":"which can be all around to create 1 nerve impulse and that occurs at an axon hillock."},{"Start":"04:17.120 ","End":"04:20.625","Text":"At the terminals of the axon,"},{"Start":"04:20.625 ","End":"04:29.870","Text":"there are synapses which are the interactions between the dendrites that are at"},{"Start":"04:29.870 ","End":"04:40.210","Text":"the end of the axon with the next cell or possibly with dendrites from another axon."},{"Start":"04:40.210 ","End":"04:42.465","Text":"Let\u0027s see how that works."},{"Start":"04:42.465 ","End":"04:48.425","Text":"The various functions of the neurons can really be divided into 3."},{"Start":"04:48.425 ","End":"04:51.920","Text":"There can be motor neurons that you see here are,"},{"Start":"04:51.920 ","End":"04:54.775","Text":"that means that they\u0027re going to be connecting."},{"Start":"04:54.775 ","End":"05:00.034","Text":"Here\u0027s the axon, which is going to be connecting to a muscle,"},{"Start":"05:00.034 ","End":"05:02.330","Text":"usually or possibly a gland, anyhow,"},{"Start":"05:02.330 ","End":"05:05.315","Text":"something which is going to be moving."},{"Start":"05:05.315 ","End":"05:10.265","Text":"There are sensory neurons that you can see here."},{"Start":"05:10.265 ","End":"05:14.360","Text":"Those will accept an impulse from a receptor and they\u0027ll"},{"Start":"05:14.360 ","End":"05:18.370","Text":"transmitted more often than not to the central nervous system,"},{"Start":"05:18.370 ","End":"05:23.990","Text":"so that could be either the brain or it could be in the spinal cord."},{"Start":"05:23.990 ","End":"05:26.810","Text":"Then there are interneurons."},{"Start":"05:26.810 ","End":"05:29.390","Text":"Those will be neurons that are going to be"},{"Start":"05:29.390 ","End":"05:33.290","Text":"connecting different kinds of neurons that will"},{"Start":"05:33.290 ","End":"05:41.070","Text":"convey nerve impulses between different parts of the CNS of the central nervous system."},{"Start":"05:41.070 ","End":"05:44.090","Text":"Now let\u0027s look at the different structures that we discussed"},{"Start":"05:44.090 ","End":"05:47.360","Text":"briefly before unipolar, bipolar, multipolar."},{"Start":"05:47.360 ","End":"05:55.530","Text":"There can also be pseudo unipolar you can see that unipolar has 1 pole,"},{"Start":"05:55.530 ","End":"05:56.930","Text":"it goes in 1 direction,"},{"Start":"05:56.930 ","End":"06:00.265","Text":"but the cell body is off to 1 side."},{"Start":"06:00.265 ","End":"06:03.290","Text":"These are these 4 different parts that"},{"Start":"06:03.290 ","End":"06:06.530","Text":"we afford different structures that in a broad sense we"},{"Start":"06:06.530 ","End":"06:12.275","Text":"discussed and the unipolar ones are found primarily in insects."},{"Start":"06:12.275 ","End":"06:16.070","Text":"They\u0027re not invertebrates, but the bipolar ones are"},{"Start":"06:16.070 ","End":"06:20.840","Text":"found usually in connection with photoreceptor cells."},{"Start":"06:20.840 ","End":"06:22.509","Text":"For instance, in the retina."},{"Start":"06:22.509 ","End":"06:29.570","Text":"Yes, the bipolar ones those goes from a sensory region to the brain."},{"Start":"06:29.570 ","End":"06:31.910","Text":"The pseudo unipolar."},{"Start":"06:31.910 ","End":"06:34.820","Text":"Those are also sensory neurons,"},{"Start":"06:34.820 ","End":"06:37.820","Text":"but the most common type are the multipolar ones,"},{"Start":"06:37.820 ","End":"06:44.950","Text":"which are found in the brain and they connect to all different kinds of other neurons."},{"Start":"06:44.950 ","End":"06:47.075","Text":"Is all this static,"},{"Start":"06:47.075 ","End":"06:49.400","Text":"or does it keep growing?"},{"Start":"06:49.400 ","End":"06:53.360","Text":"Does the nerves keep growing as an organism advances?"},{"Start":"06:53.360 ","End":"06:57.890","Text":"Well, it used to be thought that once a brain, for instance,"},{"Start":"06:57.890 ","End":"07:01.475","Text":"or nervous system reaches maturity during development,"},{"Start":"07:01.475 ","End":"07:03.800","Text":"that the cells do no longer divide,"},{"Start":"07:03.800 ","End":"07:05.500","Text":"but that\u0027s not true."},{"Start":"07:05.500 ","End":"07:09.200","Text":"It turns out that there is neurogenesis,"},{"Start":"07:09.200 ","End":"07:14.030","Text":"that\u0027s the birth of new neurons and this does continue until adulthood."},{"Start":"07:14.030 ","End":"07:20.180","Text":"It plays an important role in learning and it\u0027s very"},{"Start":"07:20.180 ","End":"07:26.765","Text":"important for maintaining the integrity of the nervous system in general."},{"Start":"07:26.765 ","End":"07:29.840","Text":"We can show it in the lab, for instance,"},{"Start":"07:29.840 ","End":"07:37.640","Text":"that new neurons are created when rats are asked to learn something new and we also know"},{"Start":"07:37.640 ","End":"07:42.500","Text":"the various medications can change neurogenesis in"},{"Start":"07:42.500 ","End":"07:48.515","Text":"the hippocampus of the brain and stress can change them as well."},{"Start":"07:48.515 ","End":"07:50.690","Text":"Now, in addition to the neurons,"},{"Start":"07:50.690 ","End":"07:52.730","Text":"we\u0027ve discussed, glial cells,"},{"Start":"07:52.730 ","End":"07:55.475","Text":"multiple different kinds of glial cells"},{"Start":"07:55.475 ","End":"07:59.030","Text":"which support and protect and nourish the neurons."},{"Start":"07:59.030 ","End":"08:04.760","Text":"There are many more of them actually than there are neurons."},{"Start":"08:04.760 ","End":"08:08.614","Text":"They fulfill various vital functions."},{"Start":"08:08.614 ","End":"08:13.535","Text":"They must be important because when there is brain cancer,"},{"Start":"08:13.535 ","End":"08:15.485","Text":"more often than not,"},{"Start":"08:15.485 ","End":"08:22.030","Text":"tumors are caused by mutations in the glial cells and not in the neurons."},{"Start":"08:22.030 ","End":"08:25.715","Text":"What are the different types of glial cells?"},{"Start":"08:25.715 ","End":"08:29.405","Text":"Well, in the central nervous system we have astrocytes,"},{"Start":"08:29.405 ","End":"08:36.210","Text":"oligodendrocytes, ependymal cells, and microglia."},{"Start":"08:36.210 ","End":"08:41.839","Text":"What are they? The astrocytes provide nutrients and structural support."},{"Start":"08:41.839 ","End":"08:45.320","Text":"The astrocytes, as you can see in here on the right,"},{"Start":"08:45.320 ","End":"08:47.915","Text":"they have a particular structure."},{"Start":"08:47.915 ","End":"08:53.390","Text":"Oligodendrocytes form a myelin sheath around the axons."},{"Start":"08:53.390 ","End":"08:56.600","Text":"They are going to be important for insulation."},{"Start":"08:56.600 ","End":"08:59.330","Text":"As our Schwann cells,"},{"Start":"08:59.330 ","End":"09:03.045","Text":"different kinds of nerves."},{"Start":"09:03.045 ","End":"09:06.440","Text":"The oligodendrocytes will be in the central nervous system,"},{"Start":"09:06.440 ","End":"09:10.340","Text":"whereas the Schwann cells will be in the peripheral nervous system."},{"Start":"09:10.340 ","End":"09:15.125","Text":"The ependymal cells produce a fluid,"},{"Start":"09:15.125 ","End":"09:19.835","Text":"a cerebrospinal fluid that cushions the neurons."},{"Start":"09:19.835 ","End":"09:20.960","Text":"That\u0027s what we see here."},{"Start":"09:20.960 ","End":"09:24.410","Text":"They excrete this fluid and then there are"},{"Start":"09:24.410 ","End":"09:28.640","Text":"other glial cells which are important in maintenance."},{"Start":"09:28.640 ","End":"09:32.455","Text":"They scavenge pathogens and dead cells."},{"Start":"09:32.455 ","End":"09:34.800","Text":"In the peripheral nervous system,"},{"Start":"09:34.800 ","End":"09:35.930","Text":"there are the Schwann cells,"},{"Start":"09:35.930 ","End":"09:37.190","Text":"as we mentioned before,"},{"Start":"09:37.190 ","End":"09:40.970","Text":"and other cells called satellite cells,"},{"Start":"09:40.970 ","End":"09:43.970","Text":"which provide nutrients and structural support to the neurons."},{"Start":"09:43.970 ","End":"09:50.670","Text":"As we discussed, that the astrocytes do in the central nervous system."}],"ID":29043}],"Thumbnail":null,"ID":275100},{"Name":"How Neurons Communicate","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Overview of neurons and synapses","Duration":"6m 23s","ChapterTopicVideoID":27867,"CourseChapterTopicPlaylistID":275101,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.710","Text":"I\u0027m glad you\u0027re back,"},{"Start":"00:01.710 ","End":"00:07.605","Text":"now to try to understand better How Neurons Communicates."},{"Start":"00:07.605 ","End":"00:12.284","Text":"In this video, we\u0027ll look very closely"},{"Start":"00:12.284 ","End":"00:17.565","Text":"at what happens when 2 neurons communicate with each other."},{"Start":"00:17.565 ","End":"00:20.370","Text":"Here we\u0027ve got something that\u0027s called a synapse."},{"Start":"00:20.370 ","End":"00:24.360","Text":"As you can see, they\u0027re little vesicles that go from 1 to the other."},{"Start":"00:24.360 ","End":"00:26.100","Text":"That\u0027s how they\u0027re going to communicate."},{"Start":"00:26.100 ","End":"00:29.685","Text":"But we\u0027re also going to try to understand how"},{"Start":"00:29.685 ","End":"00:35.280","Text":"the electrical signal moves down the axon into something like a wire,"},{"Start":"00:35.280 ","End":"00:37.215","Text":"but it\u0027s not quite a wire."},{"Start":"00:37.215 ","End":"00:40.680","Text":"Let\u0027s see in fact how this works."},{"Start":"00:40.680 ","End":"00:43.970","Text":"One neuron usually receives messages from"},{"Start":"00:43.970 ","End":"00:49.070","Text":"multiple or other neurons and is able to send the message on to other neurons."},{"Start":"00:49.070 ","End":"00:52.355","Text":"This happens between 2 different cells."},{"Start":"00:52.355 ","End":"00:55.610","Text":"Yes, so here we can see there\u0027s a neuron with its cell body"},{"Start":"00:55.610 ","End":"00:58.880","Text":"in its axon and so on with the dendrites that are inside."},{"Start":"00:58.880 ","End":"01:01.790","Text":"Then at the end of them there\u0027s something called a synapse."},{"Start":"01:01.790 ","End":"01:05.570","Text":"Let\u0027s look at the synapse a little bit more closely."},{"Start":"01:05.570 ","End":"01:10.355","Text":"That\u0027s this area between 2 different cells."},{"Start":"01:10.355 ","End":"01:16.325","Text":"There are these synaptic vesicles that contain neurotransmitters inside them."},{"Start":"01:16.325 ","End":"01:19.520","Text":"They in the pre synaptic cell,"},{"Start":"01:19.520 ","End":"01:22.455","Text":"that\u0027s the one that\u0027s delivering the message."},{"Start":"01:22.455 ","End":"01:27.949","Text":"What we find is that these vesicles then fuse with the cell membrane,"},{"Start":"01:27.949 ","End":"01:32.990","Text":"emitting the neurotransmitter to the space that\u0027s between the 2 different cells,"},{"Start":"01:32.990 ","End":"01:35.945","Text":"and then they\u0027re picked up by receptors."},{"Start":"01:35.945 ","End":"01:43.350","Text":"These neurotransmitters are picked up by receptors that are on the postsynaptic cell."},{"Start":"01:43.350 ","End":"01:51.410","Text":"That then initiates another signal down the axon of the postsynaptic cell."},{"Start":"01:51.410 ","End":"01:55.490","Text":"Each neuron has a charge cellular membrane"},{"Start":"01:55.490 ","End":"01:58.550","Text":"and nerve impulses are transmitted within the neuron."},{"Start":"01:58.550 ","End":"02:04.040","Text":"That\u0027s going to explain how the signal moves down the axon."},{"Start":"02:04.040 ","End":"02:09.485","Text":"It\u0027s going to be by the charged cellular membrane."},{"Start":"02:09.485 ","End":"02:14.120","Text":"The interaction between the cells is going to"},{"Start":"02:14.120 ","End":"02:18.485","Text":"be passed from 1 to the other via this neurotransmitter,"},{"Start":"02:18.485 ","End":"02:20.615","Text":"as I mentioned earlier."},{"Start":"02:20.615 ","End":"02:24.215","Text":"Now let\u0027s look at the charged membranes."},{"Start":"02:24.215 ","End":"02:27.995","Text":"What\u0027s happening inside the axon."},{"Start":"02:27.995 ","End":"02:34.050","Text":"First of all, this is a blowup of a small section of the axon."},{"Start":"02:34.050 ","End":"02:36.440","Text":"We see that there is the cytosol,"},{"Start":"02:36.440 ","End":"02:38.120","Text":"the inside of the cell,"},{"Start":"02:38.120 ","End":"02:40.340","Text":"and the outside of the cell."},{"Start":"02:40.340 ","End":"02:44.585","Text":"What we see in this picture is that there\u0027s a plasma membrane."},{"Start":"02:44.585 ","End":"02:46.495","Text":"Here\u0027s the plasma membrane."},{"Start":"02:46.495 ","End":"02:50.660","Text":"It is impermeable to charged molecules or ions."},{"Start":"02:50.660 ","End":"02:56.480","Text":"Why? Because it has these fatty acids that are in this bi-layer."},{"Start":"02:56.480 ","End":"03:04.280","Text":"This lipid bi-layer that does not allow the charged particles to move across it."},{"Start":"03:04.280 ","End":"03:09.410","Text":"If we measure the voltage across this membrane,"},{"Start":"03:09.410 ","End":"03:13.670","Text":"what we see is that it has a particular value."},{"Start":"03:13.670 ","End":"03:16.430","Text":"Let\u0027s say it\u0027s minus 70 millivolts,"},{"Start":"03:16.430 ","End":"03:22.790","Text":"that means that there is a potential electrical potential across this membrane."},{"Start":"03:22.790 ","End":"03:27.325","Text":"That\u0027s going to be the basis for signaling."},{"Start":"03:27.325 ","End":"03:28.940","Text":"What we do find though,"},{"Start":"03:28.940 ","End":"03:33.095","Text":"is that there are voltage-gated channels,"},{"Start":"03:33.095 ","End":"03:37.730","Text":"see in a minute there are channels that are inside this membrane."},{"Start":"03:37.730 ","End":"03:43.910","Text":"They\u0027re proteins that allow ions through under circumstances, they are voltage-gated."},{"Start":"03:43.910 ","End":"03:49.070","Text":"That means that the voltage is going to control a gate"},{"Start":"03:49.070 ","End":"03:54.860","Text":"on opening and closing channels for these ions to pass through."},{"Start":"03:54.860 ","End":"03:57.535","Text":"The membrane potential,"},{"Start":"03:57.535 ","End":"03:59.000","Text":"this is a definition."},{"Start":"03:59.000 ","End":"04:02.795","Text":"The membrane potential is the difference in total charge"},{"Start":"04:02.795 ","End":"04:07.790","Text":"between the inside and the outside of the cell."},{"Start":"04:07.790 ","End":"04:11.239","Text":"Again, the membrane potential is a difference"},{"Start":"04:11.239 ","End":"04:14.990","Text":"in total charge between inside and outside the cell."},{"Start":"04:14.990 ","End":"04:19.330","Text":"Now, that potential has 2 possibilities basically,"},{"Start":"04:19.330 ","End":"04:22.235","Text":"it has a resting potential."},{"Start":"04:22.235 ","End":"04:25.730","Text":"That\u0027s when there\u0027s no signal that is sent"},{"Start":"04:25.730 ","End":"04:29.795","Text":"and there is an action potential that\u0027s what it\u0027s called."},{"Start":"04:29.795 ","End":"04:33.095","Text":"There are action potentials that are changes in the membrane,"},{"Start":"04:33.095 ","End":"04:34.715","Text":"as we\u0027ll see in a bit,"},{"Start":"04:34.715 ","End":"04:38.670","Text":"when a signal is being sent through the membrane."},{"Start":"04:38.670 ","End":"04:42.800","Text":"Now let\u0027s blow up this picture a bit more and look at"},{"Start":"04:42.800 ","End":"04:47.015","Text":"the channels that they are in-between or inside."},{"Start":"04:47.015 ","End":"04:49.370","Text":"Again, these are proteins that as you can see,"},{"Start":"04:49.370 ","End":"04:58.655","Text":"have channels within them that allow for the movement of primarily potassium or sodium."},{"Start":"04:58.655 ","End":"05:02.440","Text":"This is a sodium channel and this is a potassium channel."},{"Start":"05:02.440 ","End":"05:06.050","Text":"You can see from this picture already that we\u0027re"},{"Start":"05:06.050 ","End":"05:09.710","Text":"going to be talking about a sodium-potassium pump that is"},{"Start":"05:09.710 ","End":"05:18.260","Text":"going to use energy at some time to open and close these channels."},{"Start":"05:18.260 ","End":"05:25.240","Text":"The sodium-potassium transporter pumps potassium ions into the cell."},{"Start":"05:25.240 ","End":"05:30.555","Text":"The potassium is going in, yes,"},{"Start":"05:30.555 ","End":"05:36.985","Text":"and the sodium is primarily going to be going out."},{"Start":"05:36.985 ","End":"05:38.780","Text":"That\u0027s what these pumps do."},{"Start":"05:38.780 ","End":"05:43.325","Text":"The sodium in, the potassium out."},{"Start":"05:43.325 ","End":"05:49.940","Text":"That will result in this roughly 70 millivolt"},{"Start":"05:49.940 ","End":"05:58.660","Text":"resting potential so that the inside of the cell is more negative than the outside."},{"Start":"05:58.660 ","End":"06:01.385","Text":"This is not a fixed value."},{"Start":"06:01.385 ","End":"06:05.525","Text":"It varies from neurons and species and so on."},{"Start":"06:05.525 ","End":"06:07.475","Text":"In the following video,"},{"Start":"06:07.475 ","End":"06:16.749","Text":"we\u0027ll look a lot more closely at what happens when sodium goes in or leaks out,"},{"Start":"06:16.749 ","End":"06:23.670","Text":"and what happens when the sodium is pumped out or leaks back in."}],"ID":29036},{"Watched":false,"Name":"Resting potentials","Duration":"6m ","ChapterTopicVideoID":27866,"CourseChapterTopicPlaylistID":275101,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.235","Text":"In our last video,"},{"Start":"00:02.235 ","End":"00:06.000","Text":"we were discussing about the movement of potassium and"},{"Start":"00:06.000 ","End":"00:11.280","Text":"sodium through this sodium-potassium pump."},{"Start":"00:11.280 ","End":"00:16.035","Text":"Now let\u0027s look at this in more detail now in this video."},{"Start":"00:16.035 ","End":"00:20.535","Text":"First, let\u0027s start by looking at the resting membrane,"},{"Start":"00:20.535 ","End":"00:22.545","Text":"the resting membrane potential."},{"Start":"00:22.545 ","End":"00:29.474","Text":"What we see is, that the sodium pumps use ATP to maintain a particular gradient."},{"Start":"00:29.474 ","End":"00:34.215","Text":"A gradient means that there is more of something on one side than there is on the other."},{"Start":"00:34.215 ","End":"00:36.075","Text":"What are we seeing?"},{"Start":"00:36.075 ","End":"00:40.060","Text":"What we see is that at resting potential,"},{"Start":"00:40.060 ","End":"00:46.430","Text":"the potassium can leak back and forth across this membrane through"},{"Start":"00:46.430 ","End":"00:54.755","Text":"potassium channels and it diffuses out of the cell at resting potential."},{"Start":"00:54.755 ","End":"01:03.430","Text":"What does that do? The inside of the cell is more negatively charged than the outside."},{"Start":"01:03.430 ","End":"01:09.920","Text":"Again, this results in a buildup of negative charge inside the neuron and this is"},{"Start":"01:09.920 ","End":"01:16.100","Text":"the major source of that resting potential between the inside and the outside."},{"Start":"01:16.100 ","End":"01:21.005","Text":"Again, it\u0027s the leakage of potassium out of the cell."},{"Start":"01:21.005 ","End":"01:25.690","Text":"Potassium. Interestingly, the permeability of"},{"Start":"01:25.690 ","End":"01:30.670","Text":"the membrane is different for different ions."},{"Start":"01:30.670 ","End":"01:36.790","Text":"Of course, that has to do with the different channels that there are in this membrane,"},{"Start":"01:36.790 ","End":"01:39.700","Text":"which itself is impermeable to the ions."},{"Start":"01:39.700 ","End":"01:43.720","Text":"We can see here that the relative permeability is such that"},{"Start":"01:43.720 ","End":"01:49.510","Text":"potassium can get through much more easily than the sodium and it leaks,"},{"Start":"01:49.510 ","End":"01:51.280","Text":"as we said to the outside."},{"Start":"01:51.280 ","End":"01:55.435","Text":"Chlorine, the negative ion doesn\u0027t move very much."},{"Start":"01:55.435 ","End":"01:59.530","Text":"Therefore, we have this negative charge on the inside of the cell."},{"Start":"01:59.530 ","End":"02:03.580","Text":"As you can see, the concentrations of these different ions is"},{"Start":"02:03.580 ","End":"02:07.670","Text":"also very different on the inside of the cell,"},{"Start":"02:07.670 ","End":"02:12.020","Text":"the intracellular concentration as opposed to the extracellular,"},{"Start":"02:12.020 ","End":"02:15.325","Text":"the outside concentration of the cell."},{"Start":"02:15.325 ","End":"02:17.690","Text":"That\u0027s the resting potential."},{"Start":"02:17.690 ","End":"02:20.270","Text":"In order for us to try to understand this better,"},{"Start":"02:20.270 ","End":"02:26.545","Text":"scientists have created an artificial membrane that can split 2 chambers."},{"Start":"02:26.545 ","End":"02:28.910","Text":"They can put into this,"},{"Start":"02:28.910 ","End":"02:30.830","Text":"these various channels,"},{"Start":"02:30.830 ","End":"02:35.840","Text":"and they can play around this way with an inside and an outside."},{"Start":"02:35.840 ","End":"02:39.380","Text":"So we have an outer chamber, as you can see up here,"},{"Start":"02:39.380 ","End":"02:44.270","Text":"an outer chamber, and this is an inner chamber, inner."},{"Start":"02:44.270 ","End":"02:48.165","Text":"In and out on this side."},{"Start":"02:48.165 ","End":"02:52.400","Text":"They can manipulate the amount of"},{"Start":"02:52.400 ","End":"02:55.895","Text":"potassium chloride and also sodium chloride that there is"},{"Start":"02:55.895 ","End":"02:59.889","Text":"on both sides of these and see what happens."},{"Start":"02:59.889 ","End":"03:01.905","Text":"With this model,"},{"Start":"03:01.905 ","End":"03:06.875","Text":"they can model the resting potential of an exon."},{"Start":"03:06.875 ","End":"03:13.580","Text":"At equilibrium, the potential is a particular amount, as we said,"},{"Start":"03:13.580 ","End":"03:16.910","Text":"and the value of the transmembrane voltage,"},{"Start":"03:16.910 ","End":"03:23.305","Text":"which diffusive and electrical forces counterbalance is this equilibrium."},{"Start":"03:23.305 ","End":"03:26.665","Text":"At this voltage there is no net flow,"},{"Start":"03:26.665 ","End":"03:33.320","Text":"so there is a concentration gradient which is trying to force things in one direction,"},{"Start":"03:33.320 ","End":"03:38.860","Text":"but there is also a voltage gradient and those two things balance."},{"Start":"03:38.860 ","End":"03:41.510","Text":"We\u0027ll create this equilibrium,"},{"Start":"03:41.510 ","End":"03:42.920","Text":"though, that of course,"},{"Start":"03:42.920 ","End":"03:47.085","Text":"also can be represented mathematically."},{"Start":"03:47.085 ","End":"03:53.120","Text":"The equilibrium potential is different for potassium and sodium,"},{"Start":"03:53.120 ","End":"03:54.815","Text":"as you can see here."},{"Start":"03:54.815 ","End":"04:00.830","Text":"That\u0027s because there\u0027s a relatively large net diffusion of potassium,"},{"Start":"04:00.830 ","End":"04:02.435","Text":"as we said before,"},{"Start":"04:02.435 ","End":"04:04.205","Text":"out of the cell,"},{"Start":"04:04.205 ","End":"04:11.450","Text":"and there is a relatively small net diffusion of sodium into the cell to neutralize it."},{"Start":"04:11.450 ","End":"04:13.890","Text":"There is some and that neutralizes some of it."},{"Start":"04:13.890 ","End":"04:20.360","Text":"That\u0027s why you see we have negative for the potassium and positive for the sodium."},{"Start":"04:20.360 ","End":"04:23.630","Text":"During the movement of a signal,"},{"Start":"04:23.630 ","End":"04:26.875","Text":"there is something called depolarization."},{"Start":"04:26.875 ","End":"04:30.830","Text":"There was polarization before of the membrane."},{"Start":"04:30.830 ","End":"04:36.065","Text":"We had this polarization that was in a resting state."},{"Start":"04:36.065 ","End":"04:42.755","Text":"Then, there can be a depolarization as"},{"Start":"04:42.755 ","End":"04:46.370","Text":"a response to an external signal that is going to"},{"Start":"04:46.370 ","End":"04:50.645","Text":"change the shape of these transporters,"},{"Start":"04:50.645 ","End":"04:53.345","Text":"as of these parts of this pump."},{"Start":"04:53.345 ","End":"04:54.980","Text":"So during the resting phase,"},{"Start":"04:54.980 ","End":"04:57.170","Text":"the currents are equal and opposite,"},{"Start":"04:57.170 ","End":"04:58.939","Text":"as we said, that\u0027s the equilibrium."},{"Start":"04:58.939 ","End":"05:01.115","Text":"But then when there\u0027s a depolarization,"},{"Start":"05:01.115 ","End":"05:05.330","Text":"there\u0027s a reduction in the extent of the membrane potential."},{"Start":"05:05.330 ","End":"05:10.096","Text":"This is because the gated sodium channels open,"},{"Start":"05:10.096 ","End":"05:16.730","Text":"so now the sodium can more easily get in and sodium diffuses into the cell."},{"Start":"05:16.730 ","End":"05:24.510","Text":"That then changes the potential until some threshold is reached."},{"Start":"05:24.510 ","End":"05:27.950","Text":"Then all of the sodium channels are opened,"},{"Start":"05:27.950 ","End":"05:32.590","Text":"which results in something called hyper-polarization."},{"Start":"05:32.590 ","End":"05:37.190","Text":"That\u0027s an increase in membrane potential when the potassium channels"},{"Start":"05:37.190 ","End":"05:42.020","Text":"also get open and the potassium diffuses out of the cell,"},{"Start":"05:42.020 ","End":"05:46.375","Text":"so you have a transition of signals."},{"Start":"05:46.375 ","End":"05:49.970","Text":"The neuron can receive, as we said,"},{"Start":"05:49.970 ","End":"05:54.155","Text":"input from other neurons and send the signals downstream."},{"Start":"05:54.155 ","End":"06:00.150","Text":"We will look at that in more detail in the next video."}],"ID":29037},{"Watched":false,"Name":"Action potentials","Duration":"6m 8s","ChapterTopicVideoID":27863,"CourseChapterTopicPlaylistID":275101,"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":"Now, we\u0027re going to continue discussing how neurons communicate."},{"Start":"00:04.380 ","End":"00:10.815","Text":"You\u0027ll remember that we\u0027ve finished in the last video with this diagram,"},{"Start":"00:10.815 ","End":"00:16.829","Text":"in which we showed the communication between 2 different cells at the synapse."},{"Start":"00:16.829 ","End":"00:20.610","Text":"As we mentioned a couple of videos ago,"},{"Start":"00:20.610 ","End":"00:25.500","Text":"there is a chemical signal where there is in the pre-synaptic cell,"},{"Start":"00:25.500 ","End":"00:29.130","Text":"there is a vesicle that will fuse"},{"Start":"00:29.130 ","End":"00:33.645","Text":"with the membrane of the pre-synaptic cell releasing neurotransmitters."},{"Start":"00:33.645 ","End":"00:37.710","Text":"Those neurotransmitters then will be picked up by receptors,"},{"Start":"00:37.710 ","End":"00:39.597","Text":"which then transmit a signal,"},{"Start":"00:39.597 ","End":"00:44.540","Text":"and that signal then will go down the next axon."},{"Start":"00:44.540 ","End":"00:52.850","Text":"Such transmission of a signal is carried between cells by a neurotransmitter."},{"Start":"00:52.850 ","End":"00:55.234","Text":"But within the neuron,"},{"Start":"00:55.234 ","End":"00:57.095","Text":"there is an electrical signal,"},{"Start":"00:57.095 ","End":"01:01.150","Text":"something called an action potential."},{"Start":"01:01.150 ","End":"01:06.740","Text":"What we can see is that over time there can be various polarizations,"},{"Start":"01:06.740 ","End":"01:09.335","Text":"depolarizations, but then all of a sudden,"},{"Start":"01:09.335 ","End":"01:11.990","Text":"there is something called an action potential"},{"Start":"01:11.990 ","End":"01:15.185","Text":"when there is a threshold which is reached and that"},{"Start":"01:15.185 ","End":"01:22.095","Text":"then makes an all-or-nothing action potential."},{"Start":"01:22.095 ","End":"01:27.350","Text":"That occurs in various magnitudes,"},{"Start":"01:27.350 ","End":"01:31.192","Text":"these early ones occur in various magnitudes."},{"Start":"01:31.192 ","End":"01:36.611","Text":"But only when there is a large change,"},{"Start":"01:36.611 ","End":"01:41.300","Text":"when there\u0027s opening and closing of many kinds of ion channels"},{"Start":"01:41.300 ","End":"01:47.050","Text":"that we get a very large action potential."},{"Start":"01:47.050 ","End":"01:50.040","Text":"In the smaller graded potentials,"},{"Start":"01:50.040 ","End":"01:52.610","Text":"there\u0027s also no refractory period,"},{"Start":"01:52.610 ","End":"01:55.430","Text":"which means that it can happen 1 right after the other."},{"Start":"01:55.430 ","End":"01:58.550","Text":"There is no period in which there is no possibility for"},{"Start":"01:58.550 ","End":"02:02.815","Text":"a change in the polarization or depolarization."},{"Start":"02:02.815 ","End":"02:04.760","Text":"However, after an action potential,"},{"Start":"02:04.760 ","End":"02:09.515","Text":"we\u0027ll see that there is a refractory period in which"},{"Start":"02:09.515 ","End":"02:15.215","Text":"the cell has to recover before making a new signal."},{"Start":"02:15.215 ","End":"02:20.390","Text":"Let\u0027s look at the action potential now in greater detail."},{"Start":"02:20.390 ","End":"02:27.580","Text":"Now, we\u0027re going to be looking at a situation like this part of this figure."},{"Start":"02:27.580 ","End":"02:36.416","Text":"What we see here is that there is a threshold in which there is first depolarization,"},{"Start":"02:36.416 ","End":"02:39.710","Text":"depolarization as there is always."},{"Start":"02:39.710 ","End":"02:44.350","Text":"But the magnitude of this is very great,"},{"Start":"02:44.350 ","End":"02:46.390","Text":"and it\u0027s always the same."},{"Start":"02:46.390 ","End":"02:49.045","Text":"It\u0027s an all-or-none phenomenon."},{"Start":"02:49.045 ","End":"02:50.920","Text":"It\u0027s the same duration,"},{"Start":"02:50.920 ","End":"02:52.660","Text":"the amount of time that passes."},{"Start":"02:52.660 ","End":"02:56.500","Text":"See this is the time axis in a particular cell type of course."},{"Start":"02:56.500 ","End":"02:58.165","Text":"It can be transmitted,"},{"Start":"02:58.165 ","End":"03:02.080","Text":"this signal over a long distance,"},{"Start":"03:02.080 ","End":"03:05.295","Text":"and of course it occurs in axons."},{"Start":"03:05.295 ","End":"03:11.770","Text":"Then we have this refractory period that returns the cell to the resting states,"},{"Start":"03:11.770 ","End":"03:16.075","Text":"and only then can a new depolarization occur."},{"Start":"03:16.075 ","End":"03:19.550","Text":"Now, let\u0027s look at the action potential more closely."},{"Start":"03:19.550 ","End":"03:25.490","Text":"We know that our resting situation is about minus 70 millivolts, so what happens?"},{"Start":"03:25.490 ","End":"03:29.000","Text":"What happens is there\u0027s a stimulus from 1 neuron that"},{"Start":"03:29.000 ","End":"03:33.140","Text":"depolarizes a target neuron to the threshold."},{"Start":"03:33.140 ","End":"03:39.485","Text":"Yes, there\u0027s this threshold that we talked about before at about minus 55."},{"Start":"03:39.485 ","End":"03:40.620","Text":"Then what happens?"},{"Start":"03:40.620 ","End":"03:44.015","Text":"What happens is that the voltage-gated sodium channels,"},{"Start":"03:44.015 ","End":"03:46.190","Text":"because now the voltage has changed,"},{"Start":"03:46.190 ","End":"03:49.460","Text":"so those channels are sensitive to that voltage and they"},{"Start":"03:49.460 ","End":"03:54.555","Text":"open allowing positive ions to enter the cell."},{"Start":"03:54.555 ","End":"03:57.930","Text":"Those are the sodium ions which are entering the cell."},{"Start":"03:57.930 ","End":"04:00.495","Text":"Then once that happens,"},{"Start":"04:00.495 ","End":"04:03.750","Text":"then the potassium channels open and the neuron"},{"Start":"04:03.750 ","End":"04:09.135","Text":"depolarizes to a membrane potential of about plus 40."},{"Start":"04:09.135 ","End":"04:11.445","Text":"That\u0027s the action potential."},{"Start":"04:11.445 ","End":"04:13.860","Text":"This is an all-or none phenomenon,"},{"Start":"04:13.860 ","End":"04:15.525","Text":"as we mentioned before."},{"Start":"04:15.525 ","End":"04:17.115","Text":"Once it\u0027s complete,"},{"Start":"04:17.115 ","End":"04:19.920","Text":"there\u0027s a reset as we saw before."},{"Start":"04:19.920 ","End":"04:23.085","Text":"All-or none law, it can be called."},{"Start":"04:23.085 ","End":"04:27.990","Text":"Now, let\u0027s look at the action potentials much more closely."},{"Start":"04:27.990 ","End":"04:31.509","Text":"What we see is that at resting,"},{"Start":"04:31.509 ","End":"04:34.515","Text":"so we\u0027re going to look at various phases here."},{"Start":"04:34.515 ","End":"04:37.579","Text":"We have first the resting potential,"},{"Start":"04:37.579 ","End":"04:43.540","Text":"then we have a potential which reaches the threshold in number 2."},{"Start":"04:43.540 ","End":"04:46.610","Text":"Notice what\u0027s happened here is that"},{"Start":"04:46.610 ","End":"04:49.880","Text":"the sodium ions at the resting cannot get into the cell,"},{"Start":"04:49.880 ","End":"04:54.020","Text":"but they can now during the depolarization."},{"Start":"04:54.020 ","End":"04:58.160","Text":"Yes, but not all of the channels are open,"},{"Start":"04:58.160 ","End":"04:59.725","Text":"just some of them,"},{"Start":"04:59.725 ","End":"05:01.910","Text":"or until it gets to the threshold."},{"Start":"05:01.910 ","End":"05:03.530","Text":"Once it gets to the threshold,"},{"Start":"05:03.530 ","End":"05:07.085","Text":"we have the action potential in which all of them"},{"Start":"05:07.085 ","End":"05:12.560","Text":"open but still the potassium is unable to get through."},{"Start":"05:12.560 ","End":"05:17.645","Text":"Then finally, once all the sodium channels get open,"},{"Start":"05:17.645 ","End":"05:22.655","Text":"then we have this large positive potential,"},{"Start":"05:22.655 ","End":"05:24.350","Text":"yes, about plus 40, we said."},{"Start":"05:24.350 ","End":"05:31.490","Text":"Then there is a repolarization in which the sodium channels are closed,"},{"Start":"05:31.490 ","End":"05:36.770","Text":"but the potassium channel opens so that the potassium now leaks back out,"},{"Start":"05:36.770 ","End":"05:39.200","Text":"diffuses back outside the cell."},{"Start":"05:39.200 ","End":"05:44.210","Text":"We have a repolarization going back to where we were before."},{"Start":"05:44.210 ","End":"05:48.740","Text":"As we said, the potassium flows out of the cell and then we"},{"Start":"05:48.740 ","End":"05:53.255","Text":"have what\u0027s called a hyperpolarization because we can have an overshoot,"},{"Start":"05:53.255 ","End":"05:55.460","Text":"but just even below the resting phase,"},{"Start":"05:55.460 ","End":"05:59.840","Text":"that once the potassium channels are all open."},{"Start":"05:59.840 ","End":"06:02.990","Text":"Then later, they will close and"},{"Start":"06:02.990 ","End":"06:08.430","Text":"the resting potential is restored as we can see over here."}],"ID":29038},{"Watched":false,"Name":"The Refractory Period And Movement of The Action Potential","Duration":"6m 22s","ChapterTopicVideoID":27864,"CourseChapterTopicPlaylistID":275101,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.170","Text":"Thanks for coming back to a video in which we will"},{"Start":"00:04.170 ","End":"00:09.180","Text":"discuss in more detail now about how neurons communicate."},{"Start":"00:09.180 ","End":"00:11.790","Text":"If we remember from the previous video,"},{"Start":"00:11.790 ","End":"00:14.820","Text":"we discussed the refractory period,"},{"Start":"00:14.820 ","End":"00:18.015","Text":"which was a time during which a cell is incapable"},{"Start":"00:18.015 ","End":"00:21.290","Text":"of repeating an action potential, refractory period."},{"Start":"00:21.290 ","End":"00:25.595","Text":"Now it turns out that this refractory period is very important"},{"Start":"00:25.595 ","End":"00:31.055","Text":"for the direction in which a signal goes down a neuron."},{"Start":"00:31.055 ","End":"00:36.380","Text":"The signals are going to go in a particular direction."},{"Start":"00:36.380 ","End":"00:40.050","Text":"They can never go back in the opposite direction,"},{"Start":"00:40.050 ","End":"00:42.990","Text":"and soon we\u0027ll understand why."},{"Start":"00:42.990 ","End":"00:46.220","Text":"As we said, the refractory period is the time during which a cell is"},{"Start":"00:46.220 ","End":"00:49.160","Text":"incapable of repeating an action potential and we had"},{"Start":"00:49.160 ","End":"00:55.580","Text":"discussed that in a previous video as this yellowish period,"},{"Start":"00:55.580 ","End":"00:59.140","Text":"which is only really part of the refractory period,"},{"Start":"00:59.140 ","End":"01:02.005","Text":"that\u0027s the relative refractory period."},{"Start":"01:02.005 ","End":"01:06.590","Text":"Let\u0027s now though speak of the absolute refractory period."},{"Start":"01:06.590 ","End":"01:08.490","Text":"That\u0027s the period of the spike,"},{"Start":"01:08.490 ","End":"01:11.850","Text":"and you remember that during that period,"},{"Start":"01:11.850 ","End":"01:16.735","Text":"the sodium channels are inactivated,"},{"Start":"01:16.735 ","End":"01:19.335","Text":"and therefore,"},{"Start":"01:19.335 ","End":"01:25.280","Text":"another action potential cannot be produced because if you remember the start of"},{"Start":"01:25.280 ","End":"01:29.780","Text":"an action potential is when sodium channels are"},{"Start":"01:29.780 ","End":"01:34.790","Text":"activated and sodium begins to leak into the cell."},{"Start":"01:34.790 ","End":"01:41.780","Text":"The absolute refractory period is because of these sodium channels which are inactivated."},{"Start":"01:41.780 ","End":"01:45.770","Text":"There are some sodium channels that are still inactive in"},{"Start":"01:45.770 ","End":"01:49.700","Text":"the relative refractory period but there are also"},{"Start":"01:49.700 ","End":"01:53.945","Text":"some voltage-gated potassium channels that are still open."},{"Start":"01:53.945 ","End":"01:57.930","Text":"The potassium channels allow the potassium to leave the cell,"},{"Start":"01:57.930 ","End":"02:05.735","Text":"so another action potential cannot occur during those 2 refractory periods."},{"Start":"02:05.735 ","End":"02:10.550","Text":"Now another one cannot start unless there"},{"Start":"02:10.550 ","End":"02:14.675","Text":"is a high depolarization value than the normal threshold."},{"Start":"02:14.675 ","End":"02:17.945","Text":"If the normal threshold were up here,"},{"Start":"02:17.945 ","End":"02:23.090","Text":"maybe another one could begin but in any case,"},{"Start":"02:23.090 ","End":"02:25.385","Text":"that doesn\u0027t usually happen."},{"Start":"02:25.385 ","End":"02:30.049","Text":"There is movement of a signal of the action potential"},{"Start":"02:30.049 ","End":"02:34.580","Text":"along a nerve in a particular direction."},{"Start":"02:34.580 ","End":"02:38.450","Text":"Here, we\u0027re looking at a piece of that nerve,"},{"Start":"02:38.450 ","End":"02:43.010","Text":"yes and you can see this is the area where there\u0027s an action potential, the blue,"},{"Start":"02:43.010 ","End":"02:47.510","Text":"and with time it moves from the left to the right,"},{"Start":"02:47.510 ","End":"02:52.320","Text":"it cannot move backwards, why?"},{"Start":"02:52.320 ","End":"02:55.100","Text":"Because as we discussed in the previous slide,"},{"Start":"02:55.100 ","End":"02:58.955","Text":"yes, there is this refractory period."},{"Start":"02:58.955 ","End":"03:01.610","Text":"That\u0027s what we see here,"},{"Start":"03:01.610 ","End":"03:05.365","Text":"this refractory period and during that period,"},{"Start":"03:05.365 ","End":"03:11.225","Text":"there cannot be stimulation of the action potential backwards, only forwards,"},{"Start":"03:11.225 ","End":"03:19.285","Text":"and that makes sure that the action potential moves only in 1 direction."},{"Start":"03:19.285 ","End":"03:24.320","Text":"The action potential is exciting only a small portion of the axon membrane,"},{"Start":"03:24.320 ","End":"03:27.710","Text":"and it starts at the axon hillock, if you remember,"},{"Start":"03:27.710 ","End":"03:34.370","Text":"which is in the cell body about here and then it moves down."},{"Start":"03:34.370 ","End":"03:38.510","Text":"Because of this thing that I described right here,"},{"Start":"03:38.510 ","End":"03:40.280","Text":"because of this refractory period,"},{"Start":"03:40.280 ","End":"03:45.880","Text":"the potential can travel in only 1 direction."},{"Start":"03:45.880 ","End":"03:52.685","Text":"What are the factors now that affect the velocity of these action potentials?"},{"Start":"03:52.685 ","End":"03:56.960","Text":"The action potential moves down the axon,"},{"Start":"03:56.960 ","End":"04:05.365","Text":"but its speed changes depending on a number of things: cell diameter, the temperature,"},{"Start":"04:05.365 ","End":"04:11.210","Text":"how insulated the axon is by myelin,"},{"Start":"04:11.210 ","End":"04:17.080","Text":"which remember is provided by Schwann cells and oligodendrocytes."},{"Start":"04:17.080 ","End":"04:20.030","Text":"The velocity, as we said,"},{"Start":"04:20.030 ","End":"04:24.380","Text":"depends on a number of different factors,"},{"Start":"04:24.620 ","End":"04:27.820","Text":"and has to do in 1,"},{"Start":"04:27.820 ","End":"04:32.090","Text":"to a large degree with the insulation, the myelin cover."},{"Start":"04:32.090 ","End":"04:33.905","Text":"Now if we look at this figure,"},{"Start":"04:33.905 ","End":"04:39.500","Text":"we\u0027ll see that there are these small regions here that"},{"Start":"04:39.500 ","End":"04:45.425","Text":"are not myelinated and those are called nodes of Ranvier."},{"Start":"04:45.425 ","End":"04:50.750","Text":"Now what are they? Because the axon is so well insulated,"},{"Start":"04:50.750 ","End":"04:57.635","Text":"it can\u0027t regenerate between these nodes that are not covered because remember,"},{"Start":"04:57.635 ","End":"05:03.665","Text":"the regeneration after action potential passes has to do with movement"},{"Start":"05:03.665 ","End":"05:11.240","Text":"of the ions across the membrane through the appropriate sodium and potassium channels."},{"Start":"05:11.240 ","End":"05:14.270","Text":"However, because of the insulation,"},{"Start":"05:14.270 ","End":"05:15.380","Text":"that can\u0027t happen,"},{"Start":"05:15.380 ","End":"05:21.080","Text":"and so the action potential will move very slowly until it gets to one of"},{"Start":"05:21.080 ","End":"05:27.150","Text":"these nodes where there can be new regeneration,"},{"Start":"05:27.150 ","End":"05:31.654","Text":"and that movement is called saltatory conduction."},{"Start":"05:31.654 ","End":"05:35.420","Text":"The impulse actually jumps from one node to the next,"},{"Start":"05:35.420 ","End":"05:40.045","Text":"and it provides very rapid conduction of impulses."},{"Start":"05:40.045 ","End":"05:46.040","Text":"You can see the difference is it would go about 11 miles per hour."},{"Start":"05:46.040 ","End":"05:49.505","Text":"The movement of the signal without the nodes, with it,"},{"Start":"05:49.505 ","End":"05:53.480","Text":"it\u0027s over 200 miles per hour, very fast."},{"Start":"05:53.480 ","End":"05:56.510","Text":"There\u0027s also conservation of energy for the cell"},{"Start":"05:56.510 ","End":"05:59.810","Text":"because the cell then doesn\u0027t have to make"},{"Start":"05:59.810 ","End":"06:07.525","Text":"these channels and put them all along the axon only in particular places."},{"Start":"06:07.525 ","End":"06:14.165","Text":"Remember there\u0027s ATP there also which has involved moving the ions into the cell,"},{"Start":"06:14.165 ","End":"06:16.340","Text":"and so that requires energy,"},{"Start":"06:16.340 ","End":"06:22.080","Text":"but it only happens in these particular nodes."}],"ID":29039},{"Watched":false,"Name":"Synapses","Duration":"7m 55s","ChapterTopicVideoID":27865,"CourseChapterTopicPlaylistID":275101,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.495","Text":"I\u0027m glad you\u0027re back now to continue our discussion of how neurons communicates,"},{"Start":"00:06.495 ","End":"00:13.110","Text":"and we\u0027re now going to look at how there is communication between different neurons."},{"Start":"00:13.110 ","End":"00:17.760","Text":"That communication will occur via something called a synapse,"},{"Start":"00:17.760 ","End":"00:19.710","Text":"something we\u0027ve discussed before,"},{"Start":"00:19.710 ","End":"00:23.010","Text":"which is where the information is transmitted from 1 neuron to another."},{"Start":"00:23.010 ","End":"00:24.120","Text":"We have 2 neurons,"},{"Start":"00:24.120 ","End":"00:27.960","Text":"we have a presynaptic one and a postsynaptic one."},{"Start":"00:27.960 ","End":"00:36.275","Text":"We have movement of the signal from the pre to the postsynaptic neuron."},{"Start":"00:36.275 ","End":"00:42.350","Text":"Most neurons, however, are both presynaptic and postsynaptic."},{"Start":"00:42.350 ","End":"00:50.135","Text":"That is, they both receive signals and can then pass on that signal to another neuron."},{"Start":"00:50.135 ","End":"00:53.270","Text":"Now, what happens at the synapse?"},{"Start":"00:53.270 ","End":"00:56.075","Text":"It turns out there are 2 different kinds of communication,"},{"Start":"00:56.075 ","End":"00:59.150","Text":"there\u0027s a chemical and electrical transmission."},{"Start":"00:59.150 ","End":"01:03.170","Text":"Let\u0027s first look at the chemical synapse."},{"Start":"01:03.170 ","End":"01:07.670","Text":"The depolarization which occurs as it\u0027s moving down"},{"Start":"01:07.670 ","End":"01:12.589","Text":"the axon and when it arrives at the end of the dendrites,"},{"Start":"01:12.589 ","End":"01:16.640","Text":"where it needs to transmit the signal to another cell,"},{"Start":"01:16.640 ","End":"01:20.630","Text":"then there is depolarization that occurs there in"},{"Start":"01:20.630 ","End":"01:24.995","Text":"a way that is not too different than we\u0027ve discussed before."},{"Start":"01:24.995 ","End":"01:32.820","Text":"There is a voltage gated, calcium signal."},{"Start":"01:32.820 ","End":"01:34.920","Text":"Here is a calcium gates,"},{"Start":"01:34.920 ","End":"01:39.620","Text":"has a calcium channel and that allows calcium into the cells"},{"Start":"01:39.620 ","End":"01:44.750","Text":"which then stimulates these vesicles to fuse with the cell membrane,"},{"Start":"01:44.750 ","End":"01:46.235","Text":"as we\u0027ve discussed earlier,"},{"Start":"01:46.235 ","End":"01:48.770","Text":"dumping neurotransmitters that were inside"},{"Start":"01:48.770 ","End":"01:51.890","Text":"the vesicles outside of the cell that are then picked"},{"Start":"01:51.890 ","End":"01:57.700","Text":"up by particular receptors that are ligand-gated ion channels."},{"Start":"01:57.700 ","End":"02:01.655","Text":"These receptors now are ion channels and they will start"},{"Start":"02:01.655 ","End":"02:06.220","Text":"a new action potential in the postsynaptic cell."},{"Start":"02:06.220 ","End":"02:12.230","Text":"It\u0027s the neurotransmitters that are moving from 1 cell to another and those are"},{"Start":"02:12.230 ","End":"02:22.574","Text":"chemical signals that are ejected into the cleft that is between the 2 cells."},{"Start":"02:22.574 ","End":"02:25.910","Text":"Later on, after this happens,"},{"Start":"02:25.910 ","End":"02:33.210","Text":"the neurotransmitter then is removed from the cleft and we\u0027ll see how in a few slides."},{"Start":"02:33.210 ","End":"02:36.320","Text":"In addition to the chemical synapse,"},{"Start":"02:36.320 ","End":"02:41.710","Text":"there\u0027s also an electrical synapse which is going to be much faster."},{"Start":"02:41.710 ","End":"02:45.170","Text":"In this case, the presynaptic and postsynaptic"},{"Start":"02:45.170 ","End":"02:49.160","Text":"membranes are very close to each other and in fact they"},{"Start":"02:49.160 ","End":"02:53.450","Text":"have channels that go between the 2 different cells"},{"Start":"02:53.450 ","End":"02:58.430","Text":"that allow electrical signals to move from one to the other."},{"Start":"02:58.430 ","End":"03:03.955","Text":"These connections or this entire junction is going to be called a gap"},{"Start":"03:03.955 ","End":"03:07.995","Text":"junction which is between"},{"Start":"03:07.995 ","End":"03:13.580","Text":"the 2 cells and it allows current to pass directly from 1 cell to the next,"},{"Start":"03:13.580 ","End":"03:17.719","Text":"of course, this is going to be much faster than the chemical synapse."},{"Start":"03:17.719 ","End":"03:20.180","Text":"Now, ions and other molecules,"},{"Start":"03:20.180 ","End":"03:21.350","Text":"such as ATP though,"},{"Start":"03:21.350 ","End":"03:26.720","Text":"can diffuse in both directions through these pores."},{"Start":"03:26.720 ","End":"03:28.640","Text":"These are not gated,"},{"Start":"03:28.640 ","End":"03:33.735","Text":"that\u0027s just a channel and they can move in different directions."},{"Start":"03:33.735 ","End":"03:36.260","Text":"Now let\u0027s look at a table that shows"},{"Start":"03:36.260 ","End":"03:40.235","Text":"the differences between chemical and electrical synapses."},{"Start":"03:40.235 ","End":"03:44.240","Text":"Of course, the electrical one is electrical that is"},{"Start":"03:44.240 ","End":"03:46.340","Text":"their ions that are moving and the chemical"},{"Start":"03:46.340 ","End":"03:48.680","Text":"one there are neurotransmitters that are moving."},{"Start":"03:48.680 ","End":"03:51.860","Text":"The electrical synapse can go in both directions,"},{"Start":"03:51.860 ","End":"03:55.610","Text":"where the chemical synapses goes in only 1 direction because"},{"Start":"03:55.610 ","End":"03:59.270","Text":"the neurotransmitter goes from the presynaptic"},{"Start":"03:59.270 ","End":"04:02.780","Text":"to the postsynaptic and there are these vesicles which are then"},{"Start":"04:02.780 ","End":"04:06.715","Text":"recognized by the receptors on the postsynaptic cell."},{"Start":"04:06.715 ","End":"04:09.465","Text":"The synapses are larger than the chemical case,"},{"Start":"04:09.465 ","End":"04:11.090","Text":"the transmission speed, of course,"},{"Start":"04:11.090 ","End":"04:18.320","Text":"is much faster than the electrical one and it\u0027s also less vulnerable to fatigue."},{"Start":"04:18.320 ","End":"04:25.130","Text":"These synapses will find more in the retina or in the brain and"},{"Start":"04:25.130 ","End":"04:28.520","Text":"the cerebral cortex but when it\u0027s"},{"Start":"04:28.520 ","End":"04:32.345","Text":"not that important that we have something going that fast,"},{"Start":"04:32.345 ","End":"04:37.910","Text":"then we have the regular chemical neurotransmitters synapses,"},{"Start":"04:37.910 ","End":"04:42.830","Text":"the chemical synapses and the capacity for signal modulation there is very high,"},{"Start":"04:42.830 ","End":"04:47.015","Text":"will find this for instance in the junctions with muscles."},{"Start":"04:47.015 ","End":"04:50.780","Text":"The generation of postsynaptic potentials"},{"Start":"04:50.780 ","End":"04:54.740","Text":"is such that neurotransmitter binding causes opening of"},{"Start":"04:54.740 ","End":"05:02.780","Text":"ion channels on the postsynaptic membrane and they can be both excitatory."},{"Start":"05:02.780 ","End":"05:10.135","Text":"In other words, they can excite or they can be inhibitory which means they can repress,"},{"Start":"05:10.135 ","End":"05:16.205","Text":"so it all depends what\u0027s neurotransmitter we\u0027re talking about."},{"Start":"05:16.205 ","End":"05:20.345","Text":"It could be glutamates which would excite,"},{"Start":"05:20.345 ","End":"05:25.620","Text":"or it could be something else called GABA which would inhibit."},{"Start":"05:25.620 ","End":"05:32.480","Text":"Of course, the stimulating one allows sodium into the cell as we\u0027ve seen before,"},{"Start":"05:32.480 ","End":"05:35.720","Text":"whereas the inhibiting one does quite the opposite,"},{"Start":"05:35.720 ","End":"05:40.445","Text":"allows the negative chlorine into the cell,"},{"Start":"05:40.445 ","End":"05:44.390","Text":"and then we have just a hyperpolarization that stops"},{"Start":"05:44.390 ","End":"05:51.395","Text":"the depolarization and it\u0027s prevents an action potential from occurring."},{"Start":"05:51.395 ","End":"05:55.160","Text":"In many cells will find that there"},{"Start":"05:55.160 ","End":"06:00.325","Text":"are lots of interactions with lots of different dendrites,"},{"Start":"06:00.325 ","End":"06:04.625","Text":"so there is a summation of post-synaptic potentials."},{"Start":"06:04.625 ","End":"06:12.650","Text":"There may be many inputs from even thousands of neurons and some synapses,"},{"Start":"06:12.650 ","End":"06:16.480","Text":"as we said, could excite while others could inhibit"},{"Start":"06:16.480 ","End":"06:21.230","Text":"and one of these is usually not enough to try."},{"Start":"06:21.230 ","End":"06:24.890","Text":"One of these synapses and one of these interactions is usually"},{"Start":"06:24.890 ","End":"06:28.790","Text":"not enough to trigger an action potential in the postsynaptic neuron."},{"Start":"06:28.790 ","End":"06:33.500","Text":"There has to be a summation of many of these interactions to"},{"Start":"06:33.500 ","End":"06:40.280","Text":"cause a new axon or an axon to create a new action potential."},{"Start":"06:40.280 ","End":"06:45.200","Text":"It\u0027s this summation which causes the action potential"},{"Start":"06:45.200 ","End":"06:50.855","Text":"to occur and that happens as we mentioned earlier at the hillock."},{"Start":"06:50.855 ","End":"06:55.100","Text":"Sometimes the summation occurs because there"},{"Start":"06:55.100 ","End":"06:59.449","Text":"are lots of these signals happening all at the same time."},{"Start":"06:59.449 ","End":"07:03.935","Text":"It\u0027s temporal summation, many addition of"},{"Start":"07:03.935 ","End":"07:10.445","Text":"single stimuli over a short period of time and that would cause an action potential."},{"Start":"07:10.445 ","End":"07:14.555","Text":"The one presynaptic neuron then generates sub thresholds,"},{"Start":"07:14.555 ","End":"07:21.280","Text":"but lots of them together very quickly will be able to generate an action potential."},{"Start":"07:21.280 ","End":"07:25.070","Text":"Another possibility is that there is spatial summation,"},{"Start":"07:25.070 ","End":"07:28.745","Text":"that is there are lots of these neurons"},{"Start":"07:28.745 ","End":"07:32.960","Text":"which interact with the cell all at the same time and they move,"},{"Start":"07:32.960 ","End":"07:38.090","Text":"there is a general movement of these neurons."},{"Start":"07:38.090 ","End":"07:41.375","Text":"They can be either closer or farther away,"},{"Start":"07:41.375 ","End":"07:46.250","Text":"so they can move 1 with respect to the other and if there are enough of them there,"},{"Start":"07:46.250 ","End":"07:49.810","Text":"they can cause a summation as well,"},{"Start":"07:49.810 ","End":"07:56.010","Text":"a spatial summation to make the action potentials more frequent."}],"ID":29040},{"Watched":false,"Name":"Control At The Synapse","Duration":"8m 38s","ChapterTopicVideoID":27868,"CourseChapterTopicPlaylistID":275101,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.995","Text":"Now let\u0027s continue with our discussion of how neurons communicate."},{"Start":"00:04.995 ","End":"00:08.460","Text":"We were discussing synapses in the previous video."},{"Start":"00:08.460 ","End":"00:13.680","Text":"Now let\u0027s see what happens when there is a chemical synapse."},{"Start":"00:13.680 ","End":"00:18.990","Text":"What happens to the neural transmitters that are still stuck in"},{"Start":"00:18.990 ","End":"00:25.410","Text":"the gap that is between the presynaptic and the postsynaptic neuron?"},{"Start":"00:25.410 ","End":"00:28.920","Text":"The termination of the signal lets the postsynaptic cell return to"},{"Start":"00:28.920 ","End":"00:33.450","Text":"its normal resting potential and it\u0027s ready for new signals to arrive."},{"Start":"00:33.450 ","End":"00:37.935","Text":"The neurotransmitters then have to be moved,"},{"Start":"00:37.935 ","End":"00:40.715","Text":"and that can happen several different ways."},{"Start":"00:40.715 ","End":"00:42.320","Text":"Either they can diffuse away,"},{"Start":"00:42.320 ","End":"00:50.270","Text":"they can be degraded by specific enzymes or they can be taken back up into the cell by"},{"Start":"00:50.270 ","End":"00:54.470","Text":"a special neurotransmitter transport channel that"},{"Start":"00:54.470 ","End":"00:59.495","Text":"moves the neurotransmitter back into the presynaptic cell."},{"Start":"00:59.495 ","End":"01:04.225","Text":"Interestingly, there are reuptake inhibitors."},{"Start":"01:04.225 ","End":"01:07.950","Text":"There are that are called SSRIs."},{"Start":"01:07.950 ","End":"01:16.655","Text":"These are the drugs that are most commonly used as antidepressants. Now what do they do?"},{"Start":"01:16.655 ","End":"01:23.900","Text":"If we look at a postsynaptic neuron and a presynaptic neuron between the 2 of them,"},{"Start":"01:23.900 ","End":"01:27.800","Text":"as we mentioned, there can be these neurotransmitters."},{"Start":"01:27.800 ","End":"01:32.870","Text":"One of them is called serotonin and there is"},{"Start":"01:32.870 ","End":"01:39.425","Text":"a specific transporter for the reuptake of it back into the cell."},{"Start":"01:39.425 ","End":"01:43.265","Text":"In a rate normal, non-depressed individual,"},{"Start":"01:43.265 ","End":"01:47.735","Text":"there is a particular amount of this serotonin between the cells."},{"Start":"01:47.735 ","End":"01:50.420","Text":"However, in someone who\u0027s depressed,"},{"Start":"01:50.420 ","End":"01:53.045","Text":"there is too much reuptake."},{"Start":"01:53.045 ","End":"01:58.625","Text":"There may be too many of these channels, and therefore,"},{"Start":"01:58.625 ","End":"02:01.385","Text":"the amount of serotonin,"},{"Start":"02:01.385 ","End":"02:05.650","Text":"which is found between the 2 is too low."},{"Start":"02:05.650 ","End":"02:11.060","Text":"Therefore, this postsynaptic membrane doesn\u0027t get enough of it."},{"Start":"02:11.060 ","End":"02:14.885","Text":"However, these drugs, these SSRIs,"},{"Start":"02:14.885 ","End":"02:20.810","Text":"can bind to these transporters blocking"},{"Start":"02:20.810 ","End":"02:26.960","Text":"the movement of the serotonin back into the presynaptic neuron."},{"Start":"02:26.960 ","End":"02:31.205","Text":"Therefore, the amount of serotonin that\u0027s left"},{"Start":"02:31.205 ","End":"02:36.999","Text":"is much more similar to what it is in the non-depressed individual."},{"Start":"02:36.999 ","End":"02:44.285","Text":"By doing this, the symptoms of moderate or even severe depression can be eased."},{"Start":"02:44.285 ","End":"02:50.585","Text":"The SSRIs block the reuptake of serotonin from the synapse into the neurons,"},{"Start":"02:50.585 ","End":"02:54.170","Text":"and it makes more serotonin available to improve transmission,"},{"Start":"02:54.170 ","End":"02:56.345","Text":"as we just said."},{"Start":"02:56.345 ","End":"03:00.035","Text":"Now let\u0027s look at different kinds of neurotransmitters."},{"Start":"03:00.035 ","End":"03:04.790","Text":"As you can see, there are a whole bunch of them, and some of them,"},{"Start":"03:04.790 ","End":"03:06.125","Text":"as we mentioned earlier,"},{"Start":"03:06.125 ","End":"03:11.245","Text":"can be inhibitory and some of them are excitatory."},{"Start":"03:11.245 ","End":"03:14.340","Text":"They\u0027re in both ways,"},{"Start":"03:14.340 ","End":"03:20.405","Text":"and of course they operate both in the CNS and in the peripheral nervous system."},{"Start":"03:20.405 ","End":"03:22.115","Text":"It just depends."},{"Start":"03:22.115 ","End":"03:27.320","Text":"A single neurotransmitter rebinds specifically to more than a dozen different receptors"},{"Start":"03:27.320 ","End":"03:28.519","Text":"and different places."},{"Start":"03:28.519 ","End":"03:30.560","Text":"This makes things much more complicated."},{"Start":"03:30.560 ","End":"03:33.470","Text":"Some neurons can release more than 1 kind of neurotransmitter,"},{"Start":"03:33.470 ","End":"03:35.870","Text":"again, allowing for complexity."},{"Start":"03:35.870 ","End":"03:39.620","Text":"A single neurotransmitter could excite cells expressing"},{"Start":"03:39.620 ","End":"03:43.940","Text":"1 receptor and inhibit cells that express different receptors."},{"Start":"03:43.940 ","End":"03:47.930","Text":"Again, depending on the cell that\u0027s receiving the neurotransmitter,"},{"Start":"03:47.930 ","End":"03:50.545","Text":"it can be affected differently."},{"Start":"03:50.545 ","End":"03:57.530","Text":"There are several groups of major neurotransmitters that are seen over here."},{"Start":"03:57.530 ","End":"03:59.300","Text":"There are the biogenic amines,"},{"Start":"03:59.300 ","End":"04:02.870","Text":"there are amino acids, there are neuropeptides, and so on."},{"Start":"04:02.870 ","End":"04:06.020","Text":"This allows for a tremendous diversity in how"},{"Start":"04:06.020 ","End":"04:09.605","Text":"these signals are both made and recognized,"},{"Start":"04:09.605 ","End":"04:14.345","Text":"and of course, the complexity of the brain is enormous."},{"Start":"04:14.345 ","End":"04:18.260","Text":"This is one level of that complexity."},{"Start":"04:18.260 ","End":"04:19.805","Text":"In addition to that,"},{"Start":"04:19.805 ","End":"04:21.980","Text":"there is synaptic plasticity."},{"Start":"04:21.980 ","End":"04:26.000","Text":"That is, that the synapses have the ability to strengthen"},{"Start":"04:26.000 ","End":"04:30.530","Text":"or weaken themselves in response to increases or decreases in their activity."},{"Start":"04:30.530 ","End":"04:36.500","Text":"If 2 synapses on the same postsynaptic cell are often active at the same time,"},{"Start":"04:36.500 ","End":"04:42.715","Text":"the strength of the postsynaptic response may increase at both synapses."},{"Start":"04:42.715 ","End":"04:47.580","Text":"This controls how effectively 2 neurons communicate with each other,"},{"Start":"04:47.580 ","End":"04:50.870","Text":"and the synaptic strength is not static."},{"Start":"04:50.870 ","End":"04:52.310","Text":"It can change."},{"Start":"04:52.310 ","End":"04:56.900","Text":"How strong the signal, what kind of a signal you need in order to get"},{"Start":"04:56.900 ","End":"05:03.530","Text":"what response changes and then increases again the amount of complexity that we have."},{"Start":"05:03.530 ","End":"05:07.250","Text":"It can also be the source of memory."},{"Start":"05:07.250 ","End":"05:11.540","Text":"You can have long-term potentiation and you can"},{"Start":"05:11.540 ","End":"05:17.180","Text":"have long-term depression of the signal depending on"},{"Start":"05:17.180 ","End":"05:23.815","Text":"which neurotransmitters we\u0027re talking about and how plastic the movement"},{"Start":"05:23.815 ","End":"05:31.010","Text":"is between the neurons and that interact with one another."},{"Start":"05:31.010 ","End":"05:37.760","Text":"Now it turns out this plasticity is very important for understanding memory and learning."},{"Start":"05:37.760 ","End":"05:41.255","Text":"In fact, we think that it\u0027s the basis of learning."},{"Start":"05:41.255 ","End":"05:43.730","Text":"That we see something, for instance,"},{"Start":"05:43.730 ","End":"05:45.920","Text":"and it\u0027s registered in our eye,"},{"Start":"05:45.920 ","End":"05:49.685","Text":"and then there is short-term and long-term memory."},{"Start":"05:49.685 ","End":"05:54.685","Text":"Those things are encoded evidently somewhat differently."},{"Start":"05:54.685 ","End":"05:59.329","Text":"The short-term memory has the capacity for holding just small amounts information,"},{"Start":"05:59.329 ","End":"06:01.160","Text":"but for a short amount of time."},{"Start":"06:01.160 ","End":"06:05.170","Text":"It happens in hippocampus region of the brain."},{"Start":"06:05.170 ","End":"06:10.325","Text":"However, long-term memory can last for a very long time as we know."},{"Start":"06:10.325 ","End":"06:13.820","Text":"These then have connections which"},{"Start":"06:13.820 ","End":"06:18.875","Text":"occur in the cerebral cortex as opposed to the hippocampus."},{"Start":"06:18.875 ","End":"06:23.105","Text":"Now let\u0027s look at long-term potentiation."},{"Start":"06:23.105 ","End":"06:24.800","Text":"In long-term potentiation,"},{"Start":"06:24.800 ","End":"06:28.100","Text":"there\u0027s a persistent strengthening of the synaptic connection as we see before."},{"Start":"06:28.100 ","End":"06:31.685","Text":"This is called the Hebbian principle,"},{"Start":"06:31.685 ","End":"06:34.250","Text":"after the person who described it."},{"Start":"06:34.250 ","End":"06:37.700","Text":"That means that cells that fire together, wire together."},{"Start":"06:37.700 ","End":"06:40.165","Text":"In other words, the more firing there is."},{"Start":"06:40.165 ","End":"06:43.310","Text":"That means that the cells that fire all"},{"Start":"06:43.310 ","End":"06:46.280","Text":"at the same time are also going to be wired together,"},{"Start":"06:46.280 ","End":"06:49.590","Text":"going to be bundled together."},{"Start":"06:49.590 ","End":"06:54.200","Text":"That then involves presynaptic neuron releasing"},{"Start":"06:54.200 ","End":"06:59.870","Text":"excitatory neurotransmitter and a postsynaptic neuron"},{"Start":"06:59.870 ","End":"07:03.185","Text":"that has different kinds of receptors,"},{"Start":"07:03.185 ","End":"07:08.730","Text":"NMDA and AMPA glutamate receptors,"},{"Start":"07:08.730 ","End":"07:12.620","Text":"and the activation of the NMDA receptors"},{"Start":"07:12.620 ","End":"07:16.940","Text":"stimulates the insertion of these other receptors into the post-synaptic membrane."},{"Start":"07:16.940 ","End":"07:23.240","Text":"There is a strengthening of the potentiation that we can see down here,"},{"Start":"07:23.240 ","End":"07:26.885","Text":"so this is an establishment and then there is"},{"Start":"07:26.885 ","End":"07:31.670","Text":"continuing increase in the strength of the signal."},{"Start":"07:31.670 ","End":"07:35.540","Text":"This makes the postsynaptic neuron more likely to"},{"Start":"07:35.540 ","End":"07:39.545","Text":"fire in response to a particular signal."},{"Start":"07:39.545 ","End":"07:43.330","Text":"Now there can also be long-term depression, of course."},{"Start":"07:43.330 ","End":"07:45.544","Text":"In the case of long-term depression,"},{"Start":"07:45.544 ","End":"07:48.710","Text":"there is a long-term weakening of the synaptic connections just"},{"Start":"07:48.710 ","End":"07:51.680","Text":"the opposite as we saw before in the synapse."},{"Start":"07:51.680 ","End":"07:57.680","Text":"In this case, calcium enters through the NMDA receptors that we saw before and it"},{"Start":"07:57.680 ","End":"08:00.680","Text":"results now this time in the removal of"},{"Start":"08:00.680 ","End":"08:04.445","Text":"the AMPA receptors from the postsynaptic membrane,"},{"Start":"08:04.445 ","End":"08:11.465","Text":"and that is going to decrease the signal that\u0027s received."},{"Start":"08:11.465 ","End":"08:15.320","Text":"This allows for unimportant connections or ones that we"},{"Start":"08:15.320 ","End":"08:19.405","Text":"want to stop or the cell ones that stop from functioning."},{"Start":"08:19.405 ","End":"08:21.885","Text":"That\u0027s what we see over here."},{"Start":"08:21.885 ","End":"08:24.410","Text":"This makes the synapses that have undergone"},{"Start":"08:24.410 ","End":"08:29.544","Text":"the long-term potentiation that much stronger by comparison."},{"Start":"08:29.544 ","End":"08:32.810","Text":"This is a depression of some of the synapses,"},{"Start":"08:32.810 ","End":"08:34.580","Text":"and then by comparison, of course,"},{"Start":"08:34.580 ","End":"08:38.760","Text":"the potentiated ones are much stronger."}],"ID":29041}],"Thumbnail":null,"ID":275101},{"Name":"The Central Nervous System","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Introduction to the CNS","Duration":"6m 19s","ChapterTopicVideoID":27862,"CourseChapterTopicPlaylistID":275102,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.210 ","End":"00:05.155","Text":"Hi, welcome to the section about the nervous system."},{"Start":"00:05.155 ","End":"00:11.260","Text":"In this section, we\u0027re going to describe both the central nervous system and"},{"Start":"00:11.260 ","End":"00:14.710","Text":"the peripheral nervous system and explain"},{"Start":"00:14.710 ","End":"00:19.180","Text":"how they each work and how they interact with each other."},{"Start":"00:19.180 ","End":"00:23.545","Text":"The central nervous system, or the CNS,"},{"Start":"00:23.545 ","End":"00:26.565","Text":"has 3 main components,"},{"Start":"00:26.565 ","End":"00:28.085","Text":"which are the brain."},{"Start":"00:28.085 ","End":"00:30.505","Text":"Yes, which is of course in the head,"},{"Start":"00:30.505 ","End":"00:33.310","Text":"and the spinal cord,"},{"Start":"00:33.310 ","End":"00:38.410","Text":"as you can see here in the red which goes down into our back as we know."},{"Start":"00:38.410 ","End":"00:42.890","Text":"Of course, the nerve cells, the neurons."},{"Start":"00:42.890 ","End":"00:50.785","Text":"As we will see, this system exists in many different animals,"},{"Start":"00:50.785 ","End":"00:55.480","Text":"extending from even something like the hydra in which"},{"Start":"00:55.480 ","End":"01:00.715","Text":"it\u0027s nerve network is not nearly as organized as the central nervous system and us,"},{"Start":"01:00.715 ","End":"01:03.385","Text":"as well as in various insects,"},{"Start":"01:03.385 ","End":"01:07.770","Text":"earthworms, even planaria, all things."},{"Start":"01:07.770 ","End":"01:13.554","Text":"It has a central role in the control of not only our thinking,"},{"Start":"01:13.554 ","End":"01:19.975","Text":"but most bodily functions and sensations, thoughts, speech, memory."},{"Start":"01:19.975 ","End":"01:26.255","Text":"In fact, it controls pretty much everything that goes on in the human body."},{"Start":"01:26.255 ","End":"01:32.230","Text":"We\u0027ll see that not all animals with a central nervous system though have a brain."},{"Start":"01:32.230 ","End":"01:34.900","Text":"Although a large majority do, of course,"},{"Start":"01:34.900 ","End":"01:37.660","Text":"the ones that are more developed have more of a brain"},{"Start":"01:37.660 ","End":"01:41.065","Text":"than the ones that are less developed."},{"Start":"01:41.065 ","End":"01:43.510","Text":"In this discussion, however,"},{"Start":"01:43.510 ","End":"01:47.290","Text":"we\u0027re going to look primarily at the human brain"},{"Start":"01:47.290 ","End":"01:51.760","Text":"and we\u0027ll discuss a little bit about its evolution."},{"Start":"01:51.760 ","End":"01:53.845","Text":"In order to understand the brain,"},{"Start":"01:53.845 ","End":"01:58.995","Text":"we do something that we often do with multicellular organisms."},{"Start":"01:58.995 ","End":"02:03.310","Text":"That is we look at different sections of the brain and we\u0027re going"},{"Start":"02:03.310 ","End":"02:07.930","Text":"to divide the brain in different directions."},{"Start":"02:07.930 ","End":"02:12.545","Text":"Will be able to divide the brain up and down,"},{"Start":"02:12.545 ","End":"02:14.000","Text":"as you can see here,"},{"Start":"02:14.000 ","End":"02:16.900","Text":"up and down, and so you\u0027ll get a right and left side."},{"Start":"02:16.900 ","End":"02:20.035","Text":"We\u0027ll divide it right in the middle,"},{"Start":"02:20.035 ","End":"02:22.075","Text":"so we\u0027ll have a front and back."},{"Start":"02:22.075 ","End":"02:23.720","Text":"Then there are 3 dimensions, of course,"},{"Start":"02:23.720 ","End":"02:27.530","Text":"so we can divide it across the middle and we\u0027ll have a top"},{"Start":"02:27.530 ","End":"02:32.015","Text":"and bottom and each of those things then we\u0027ll have a name."},{"Start":"02:32.015 ","End":"02:37.100","Text":"The right to left will be called the sagittal section."},{"Start":"02:37.100 ","End":"02:42.410","Text":"The coronal section is cutting the brain front to back."},{"Start":"02:42.410 ","End":"02:44.630","Text":"The horizontal section of course,"},{"Start":"02:44.630 ","End":"02:46.500","Text":"cuts it across the middle,"},{"Start":"02:46.500 ","End":"02:49.410","Text":"and so we\u0027ll have a top and bottom."},{"Start":"02:49.410 ","End":"02:52.580","Text":"Now, looking at the brain,"},{"Start":"02:52.580 ","End":"02:55.475","Text":"we know that it has all crevices in it."},{"Start":"02:55.475 ","End":"02:58.090","Text":"It has all different parts to it."},{"Start":"02:58.090 ","End":"03:00.990","Text":"You can see this when you do the cross-sections."},{"Start":"03:00.990 ","End":"03:04.775","Text":"You can see it even looking just at the outside of the brain."},{"Start":"03:04.775 ","End":"03:07.820","Text":"There are all layers."},{"Start":"03:07.820 ","End":"03:10.070","Text":"They have all different functions."},{"Start":"03:10.070 ","End":"03:15.315","Text":"We\u0027re going to describe those things in a lot more detail."},{"Start":"03:15.315 ","End":"03:17.880","Text":"Let\u0027s start with that,"},{"Start":"03:17.880 ","End":"03:23.810","Text":"in which we\u0027ll look at the cover for both the brain and the spinal cord,"},{"Start":"03:23.810 ","End":"03:25.955","Text":"and this is called the meninges."},{"Start":"03:25.955 ","End":"03:27.350","Text":"This is the cover."},{"Start":"03:27.350 ","End":"03:28.520","Text":"If we look here at the brain,"},{"Start":"03:28.520 ","End":"03:33.465","Text":"it\u0027s what is between the scalp and the brain itself."},{"Start":"03:33.465 ","End":"03:39.560","Text":"You can see it\u0027s made of different layers that are going to have different functions."},{"Start":"03:39.560 ","End":"03:41.480","Text":"There\u0027s a Dura mater on top,"},{"Start":"03:41.480 ","End":"03:45.870","Text":"the Arachnoid mater that is below it,"},{"Start":"03:45.870 ","End":"03:47.145","Text":"and the Pia mater,"},{"Start":"03:47.145 ","End":"03:49.530","Text":"which is below that."},{"Start":"03:49.530 ","End":"03:53.640","Text":"These are all parts of the meninges."},{"Start":"03:53.640 ","End":"03:57.530","Text":"We\u0027ll see that the Dura mater,"},{"Start":"03:57.530 ","End":"04:00.410","Text":"which is this outer thicker parts,"},{"Start":"04:00.410 ","End":"04:01.790","Text":"first of all, is a thick layer."},{"Start":"04:01.790 ","End":"04:05.150","Text":"It\u0027s a protective layer and it\u0027s got these vein like structures"},{"Start":"04:05.150 ","End":"04:08.750","Text":"that carry blood vessels from the brain back to the heart."},{"Start":"04:08.750 ","End":"04:10.940","Text":"There\u0027s the arachnoid mater,"},{"Start":"04:10.940 ","End":"04:13.450","Text":"which is the middle layer, of course."},{"Start":"04:13.450 ","End":"04:15.640","Text":"It is more web-like."},{"Start":"04:15.640 ","End":"04:17.575","Text":"That\u0027s why it\u0027s called arachnoid."},{"Start":"04:17.575 ","End":"04:19.720","Text":"Things having to do with insects."},{"Start":"04:19.720 ","End":"04:21.459","Text":"You\u0027d have this word arachnoid."},{"Start":"04:21.459 ","End":"04:27.010","Text":"But so, it\u0027s got a web-like suspension and it protects the brain from a sudden impact."},{"Start":"04:27.010 ","End":"04:29.455","Text":"It\u0027s like a shock absorber."},{"Start":"04:29.455 ","End":"04:32.215","Text":"Then under that is the Pia mater."},{"Start":"04:32.215 ","End":"04:38.320","Text":"Inner layer which directly contexts the brain itself and the spinal cord as well."},{"Start":"04:38.320 ","End":"04:45.175","Text":"It contains within it some fluid called the cerebrospinal fluid."},{"Start":"04:45.175 ","End":"04:48.940","Text":"It\u0027s a fluid which cushions the brain and the spine and it"},{"Start":"04:48.940 ","End":"04:52.720","Text":"also is continually being moved."},{"Start":"04:52.720 ","End":"04:58.755","Text":"It\u0027s circulating between the brain and the spinal cord."},{"Start":"04:58.755 ","End":"05:02.855","Text":"Here you can see this cerebrospinal fluid,"},{"Start":"05:02.855 ","End":"05:09.320","Text":"which is moving between the brain and the spinal cord."},{"Start":"05:09.320 ","End":"05:12.035","Text":"When there is a disruption in that movement,"},{"Start":"05:12.035 ","End":"05:14.435","Text":"there is big trouble."},{"Start":"05:14.435 ","End":"05:17.495","Text":"Let\u0027s look a minute at this cerebrospinal fluid."},{"Start":"05:17.495 ","End":"05:20.570","Text":"Let\u0027s look at the cerebrospinal fluid."},{"Start":"05:20.570 ","End":"05:24.805","Text":"It fills the space between the arachnoid and pia mater,"},{"Start":"05:24.805 ","End":"05:26.882","Text":"as we had said before."},{"Start":"05:26.882 ","End":"05:30.190","Text":"It\u0027s produced in the middle of the brain."},{"Start":"05:30.190 ","End":"05:38.290","Text":"This area here called the choroid plexus and an area called the ventricles of the brain."},{"Start":"05:38.290 ","End":"05:39.860","Text":"The ventricles of the brain,"},{"Start":"05:39.860 ","End":"05:47.820","Text":"which are in the middle and It\u0027s continuous with the spinal cord, as we said."},{"Start":"05:47.820 ","End":"05:53.970","Text":"It acts as a shock absorber and is also makes the brain buoyant."},{"Start":"05:53.970 ","End":"05:56.870","Text":"It floats in this solution because it"},{"Start":"05:56.870 ","End":"06:00.275","Text":"doesn\u0027t have any other structure in it that supports it."},{"Start":"06:00.275 ","End":"06:03.195","Text":"It is floating in this."},{"Start":"06:03.195 ","End":"06:05.490","Text":"It\u0027s circulates, as we said."},{"Start":"06:05.490 ","End":"06:08.510","Text":"It circulates together with other substances throughout"},{"Start":"06:08.510 ","End":"06:11.955","Text":"the brain and into the spinal cord."},{"Start":"06:11.955 ","End":"06:13.310","Text":"In the next videos,"},{"Start":"06:13.310 ","End":"06:19.410","Text":"we\u0027ll look in greater detail at the various parts of the brain."}],"ID":29044},{"Watched":false,"Name":"Functional and structural aspects of the human brain","Duration":"6m 8s","ChapterTopicVideoID":27861,"CourseChapterTopicPlaylistID":275102,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.588","Text":"Let\u0027s continue our discussion now of the central nervous system,"},{"Start":"00:05.588 ","End":"00:09.855","Text":"and briefly look at the evolution of the brain in the sense of"},{"Start":"00:09.855 ","End":"00:14.789","Text":"what it looks like in different organisms."},{"Start":"00:14.789 ","End":"00:16.230","Text":"Primarily, as I said,"},{"Start":"00:16.230 ","End":"00:18.225","Text":"we\u0027re going to discuss the human."},{"Start":"00:18.225 ","End":"00:20.250","Text":"But as you can see,"},{"Start":"00:20.250 ","End":"00:23.940","Text":"there are similarities between different organisms"},{"Start":"00:23.940 ","End":"00:28.710","Text":"stretching all the way from fish to human."},{"Start":"00:28.710 ","End":"00:34.020","Text":"In fact, the main feature that is common"},{"Start":"00:34.020 ","End":"00:39.425","Text":"between the different brains is the division between a forebrain,"},{"Start":"00:39.425 ","End":"00:42.140","Text":"a midbrain, and a hindbrain,"},{"Start":"00:42.140 ","End":"00:44.990","Text":"as you can see in the colorations here."},{"Start":"00:44.990 ","End":"00:50.030","Text":"They are similar in structure though,"},{"Start":"00:50.030 ","End":"00:52.520","Text":"but there is a difference in size,"},{"Start":"00:52.520 ","End":"00:55.010","Text":"as you can see, between the different parts."},{"Start":"00:55.010 ","End":"00:59.260","Text":"Say, the forebrain is much smaller in fish than it is in humans,"},{"Start":"00:59.260 ","End":"01:02.225","Text":"and it will be no surprise to you to find out that"},{"Start":"01:02.225 ","End":"01:07.285","Text":"this forebrain is really what does most of the thinking."},{"Start":"01:07.285 ","End":"01:09.445","Text":"It seems that in evolution,"},{"Start":"01:09.445 ","End":"01:13.279","Text":"these began as 3 bulges in the anterior end of the spinal cord."},{"Start":"01:13.279 ","End":"01:14.960","Text":"That\u0027s the front of the spinal cord,"},{"Start":"01:14.960 ","End":"01:16.350","Text":"and it\u0027s present,"},{"Start":"01:16.350 ","End":"01:18.400","Text":"of course, in all vertebrates."},{"Start":"01:18.400 ","End":"01:21.840","Text":"There are these 3 sections, as we discussed."},{"Start":"01:21.840 ","End":"01:24.975","Text":"There is the prosencephalon,"},{"Start":"01:24.975 ","End":"01:30.660","Text":"the mesencephalon and the rhombencephalon."},{"Start":"01:30.660 ","End":"01:32.495","Text":"These are the forebrain, midbrain,"},{"Start":"01:32.495 ","End":"01:35.915","Text":"and hindbrain in each of these organisms,"},{"Start":"01:35.915 ","End":"01:41.015","Text":"and in more complex brains we further subdivide these,"},{"Start":"01:41.015 ","End":"01:44.240","Text":"so that we can understand better what"},{"Start":"01:44.240 ","End":"01:50.680","Text":"the different pieces of the brains do in the complex tasks."},{"Start":"01:50.680 ","End":"01:53.905","Text":"Looking at that in more detail,"},{"Start":"01:53.905 ","End":"01:57.259","Text":"we know that during the embryonic stage the forebrain,"},{"Start":"01:57.259 ","End":"02:03.245","Text":"midbrain and hindbrain develop from something called the neural tube."},{"Start":"02:03.245 ","End":"02:05.900","Text":"It\u0027s something which we find,"},{"Start":"02:05.900 ","End":"02:08.180","Text":"the structure that we find that early embryos,"},{"Start":"02:08.180 ","End":"02:10.085","Text":"and as the embryo develops,"},{"Start":"02:10.085 ","End":"02:12.440","Text":"different parts of the brain, of course,"},{"Start":"02:12.440 ","End":"02:19.910","Text":"develop separately one from the other into structures though we can\u0027t give names to."},{"Start":"02:19.910 ","End":"02:26.285","Text":"The forebrain then subdivides into the cerebrum and the diencephalon,"},{"Start":"02:26.285 ","End":"02:29.735","Text":"which forms the endocrine tissues in the brain,"},{"Start":"02:29.735 ","End":"02:31.270","Text":"as we\u0027ll see a little bit later."},{"Start":"02:31.270 ","End":"02:36.635","Text":"The midbrain then can also be divided into these various parts."},{"Start":"02:36.635 ","End":"02:43.245","Text":"The hindbrain develops primarily into this cerebellum,"},{"Start":"02:43.245 ","End":"02:45.675","Text":"which is part of the hindbrain."},{"Start":"02:45.675 ","End":"02:54.440","Text":"Let\u0027s now first start looking at the cerebrum or the telencephalon."},{"Start":"02:54.440 ","End":"02:57.785","Text":"They\u0027re more commonly called the cerebrum."},{"Start":"02:57.785 ","End":"03:02.345","Text":"The cerebrum includes 2 different parts."},{"Start":"03:02.345 ","End":"03:04.250","Text":"There\u0027s the cerebral cortex,"},{"Start":"03:04.250 ","End":"03:07.380","Text":"which is the outer layer,"},{"Start":"03:07.670 ","End":"03:14.360","Text":"and there\u0027s the more inner parts which are the basal ganglia."},{"Start":"03:14.360 ","End":"03:16.490","Text":"It\u0027s a group of subcortical,"},{"Start":"03:16.490 ","End":"03:19.130","Text":"that means inside the cortex,"},{"Start":"03:19.130 ","End":"03:26.400","Text":"and it\u0027s subcortical nuclei that come from different places during development,"},{"Start":"03:26.400 ","End":"03:29.330","Text":"the sub basal ganglia,"},{"Start":"03:29.330 ","End":"03:32.720","Text":"are responsible primarily for motor control as well as"},{"Start":"03:32.720 ","End":"03:37.040","Text":"other motor learning executive functions and behaviors and emotions."},{"Start":"03:37.040 ","End":"03:40.685","Text":"We\u0027ll see more of those things a little bit later."},{"Start":"03:40.685 ","End":"03:43.115","Text":"Now in the coming pictures,"},{"Start":"03:43.115 ","End":"03:49.880","Text":"we\u0027ll see a picture on our lower left that shows the head of a person and discusses,"},{"Start":"03:49.880 ","End":"03:52.730","Text":"and it highlights the area that we\u0027re discussing."},{"Start":"03:52.730 ","End":"03:56.000","Text":"Here we\u0027re talking about the cerebral cortex."},{"Start":"03:56.000 ","End":"04:00.875","Text":"You can see that\u0027s the outer area or it\u0027s primarily this large part of the brain,"},{"Start":"04:00.875 ","End":"04:03.140","Text":"not so much to the inside."},{"Start":"04:03.140 ","End":"04:11.060","Text":"This cerebral cortex then has on its outside all these various indentations."},{"Start":"04:11.060 ","End":"04:14.750","Text":"We call those indentations gyri,"},{"Start":"04:14.750 ","End":"04:16.235","Text":"they\u0027re these hills,"},{"Start":"04:16.235 ","End":"04:19.670","Text":"and sulci, they\u0027re the valleys."},{"Start":"04:19.670 ","End":"04:23.345","Text":"We have sulcus and the gyrus,"},{"Start":"04:23.345 ","End":"04:25.505","Text":"the valley and the hill."},{"Start":"04:25.505 ","End":"04:28.220","Text":"This area is what\u0027s important in"},{"Start":"04:28.220 ","End":"04:31.340","Text":"the conscious thought processes of learning, emotion, memory,"},{"Start":"04:31.340 ","End":"04:37.230","Text":"various intellectual functions as well as skeletal muscle contraction."},{"Start":"04:37.230 ","End":"04:42.935","Text":"Now some of the functions like speech are localized"},{"Start":"04:42.935 ","End":"04:48.815","Text":"in various sections of the cerebral cortex and interestingly,"},{"Start":"04:48.815 ","End":"04:50.150","Text":"they can be divided."},{"Start":"04:50.150 ","End":"04:55.200","Text":"Sometimes you will find them in one hemisphere more than the other."},{"Start":"04:55.200 ","End":"04:57.725","Text":"So we can have a right hemisphere and"},{"Start":"04:57.725 ","End":"05:04.095","Text":"a left hemisphere if we divide the brain in the proper way."},{"Start":"05:04.095 ","End":"05:08.270","Text":"We know that people that have disease, for instance,"},{"Start":"05:08.270 ","End":"05:13.850","Text":"sometimes can\u0027t speak when they have a lesion in one side of the brain."},{"Start":"05:13.850 ","End":"05:21.920","Text":"That\u0027s the way we know how the functions are localized in one hemisphere versus another."},{"Start":"05:21.920 ","End":"05:30.100","Text":"There\u0027s this area called the corpus callosum that connects the 2 cerebral sides,"},{"Start":"05:30.590 ","End":"05:37.520","Text":"and each of the sides then handles different functions."},{"Start":"05:37.520 ","End":"05:44.700","Text":"Those different sides we can describe as different lobes of the brain."},{"Start":"05:44.700 ","End":"05:46.810","Text":"As you can see from this figure,"},{"Start":"05:46.810 ","End":"05:51.070","Text":"the different lobes have different functions."},{"Start":"05:51.070 ","End":"05:55.265","Text":"We\u0027ll call those lobes frontal, parietal,"},{"Start":"05:55.265 ","End":"05:58.505","Text":"temporal, and occipital lobes,"},{"Start":"05:58.505 ","End":"06:01.295","Text":"each with different functions."},{"Start":"06:01.295 ","End":"06:02.750","Text":"In the next video,"},{"Start":"06:02.750 ","End":"06:08.610","Text":"we will concentrate more on what each of the lobes does."}],"ID":29045},{"Watched":false,"Name":"Lobes in the brain and their functions","Duration":"6m 20s","ChapterTopicVideoID":27858,"CourseChapterTopicPlaylistID":275102,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.863","Text":"Welcome back to our discussion of the central nervous system,"},{"Start":"00:03.863 ","End":"00:08.970","Text":"and in particular to the discussion of the structure of the human brain."},{"Start":"00:08.970 ","End":"00:15.040","Text":"We were discussing the various lobes and that each of them has different functions."},{"Start":"00:15.040 ","End":"00:20.010","Text":"For example, the frontal lobe has the functions of voluntary movement,"},{"Start":"00:20.010 ","End":"00:24.615","Text":"planning, intellect, problem solving, abstract reasoning."},{"Start":"00:24.615 ","End":"00:27.510","Text":"Each of these lobes has different functions,"},{"Start":"00:27.510 ","End":"00:31.544","Text":"and of course, the human brain is extremely complicated,"},{"Start":"00:31.544 ","End":"00:34.980","Text":"and has all different functions that are involved"},{"Start":"00:34.980 ","End":"00:39.090","Text":"both in things that we think about and things that we don\u0027t."},{"Start":"00:39.090 ","End":"00:44.280","Text":"We\u0027ll see that in greater detail as we move forward."},{"Start":"00:44.280 ","End":"00:48.050","Text":"As we said, each of these lobes handles"},{"Start":"00:48.050 ","End":"00:53.315","Text":"a specific segment of the cerebrum, of its function."},{"Start":"00:53.315 ","End":"00:57.640","Text":"Now, let\u0027s look in more detail at the frontal lobe."},{"Start":"00:57.640 ","End":"01:00.290","Text":"As I mentioned in the previous video,"},{"Start":"01:00.290 ","End":"01:03.380","Text":"these figures at the bottom here will show"},{"Start":"01:03.380 ","End":"01:08.845","Text":"the entire head with the brain end shows the area that we\u0027re discussing."},{"Start":"01:08.845 ","End":"01:13.100","Text":"The frontal lobe is the most anterior,"},{"Start":"01:13.100 ","End":"01:14.390","Text":"the forward part of the brain,"},{"Start":"01:14.390 ","End":"01:16.500","Text":"and it\u0027s located over the eyes,"},{"Start":"01:16.500 ","End":"01:22.750","Text":"and it\u0027s primarily involved in these cognitive functions that we discussed a minute ago."},{"Start":"01:22.750 ","End":"01:29.870","Text":"It contains however, different parts that we can also sub-divide."},{"Start":"01:29.870 ","End":"01:36.010","Text":"For instance, there\u0027s the olfactory bulb which is involved in smell."},{"Start":"01:36.010 ","End":"01:42.225","Text":"Olfactory has to do with smell processing."},{"Start":"01:42.225 ","End":"01:44.340","Text":"We can see in fact,"},{"Start":"01:44.340 ","End":"01:45.900","Text":"that this frontal lobe,"},{"Start":"01:45.900 ","End":"01:48.180","Text":"now we\u0027re looking at the back part of it,"},{"Start":"01:48.180 ","End":"01:55.315","Text":"controls various neurons that are involved in movement, motor neurons."},{"Start":"01:55.315 ","End":"01:58.345","Text":"This is the primary motor cortex,"},{"Start":"01:58.345 ","End":"02:03.045","Text":"which is the back of the frontal lobe."},{"Start":"02:03.045 ","End":"02:06.650","Text":"Now, we\u0027re looking at it from the side."},{"Start":"02:06.650 ","End":"02:11.165","Text":"Different parts of this lobe will control different areas,"},{"Start":"02:11.165 ","End":"02:13.940","Text":"let\u0027s say the lips, the upper lip, the face, nose."},{"Start":"02:13.940 ","End":"02:19.075","Text":"Notice that these are close together on the face."},{"Start":"02:19.075 ","End":"02:20.953","Text":"These various pieces,"},{"Start":"02:20.953 ","End":"02:25.865","Text":"and they are also grouped together in a particular place on"},{"Start":"02:25.865 ","End":"02:31.410","Text":"this area of the primary motor cortex."},{"Start":"02:31.410 ","End":"02:33.680","Text":"That\u0027s really very interesting."},{"Start":"02:33.680 ","End":"02:39.740","Text":"We\u0027ll see in a minute that the sensory areas which are going to be just behind"},{"Start":"02:39.740 ","End":"02:46.765","Text":"this frontal primary motor cortex are also going to be organized in the same way."},{"Start":"02:46.765 ","End":"02:51.170","Text":"Behind the frontal lobe is the parietal lobe,"},{"Start":"02:51.170 ","End":"02:52.805","Text":"as you can see over here,"},{"Start":"02:52.805 ","End":"02:54.935","Text":"and it\u0027s located at the top of the brain,"},{"Start":"02:54.935 ","End":"02:59.440","Text":"and it is primarily involved in speech and reading."},{"Start":"02:59.440 ","End":"03:04.095","Text":"There is the processing of the sensations,"},{"Start":"03:04.095 ","End":"03:08.055","Text":"this area that we just alluded to before,"},{"Start":"03:08.055 ","End":"03:11.990","Text":"that processes sensations of touch,"},{"Start":"03:11.990 ","End":"03:14.420","Text":"pressure, pain, heat, cold, and so on."},{"Start":"03:14.420 ","End":"03:18.590","Text":"Notice that the organization is the same"},{"Start":"03:18.590 ","End":"03:23.480","Text":"as it was here when we discussed the frontal lobe."},{"Start":"03:23.480 ","End":"03:26.660","Text":"That\u0027s a really interesting and important things"},{"Start":"03:26.660 ","End":"03:30.935","Text":"because there is communication front and back here,"},{"Start":"03:30.935 ","End":"03:35.240","Text":"and it\u0027s spatially organized in the same way."},{"Start":"03:35.240 ","End":"03:41.720","Text":"As we said, this area is involved in the sensations of touch,"},{"Start":"03:41.720 ","End":"03:44.675","Text":"pressure, pain, heat, cold, and so on."},{"Start":"03:44.675 ","End":"03:50.720","Text":"Then there is the idea of how various body parts are oriented in space."},{"Start":"03:50.720 ","End":"03:52.298","Text":"There\u0027s a perception that we have,"},{"Start":"03:52.298 ","End":"03:56.330","Text":"that we understand how our body parts are oriented and"},{"Start":"03:56.330 ","End":"04:00.780","Text":"that is also processed in this same region."},{"Start":"04:00.780 ","End":"04:06.455","Text":"This has to do with a certain map that is set out,"},{"Start":"04:06.455 ","End":"04:07.670","Text":"and as we said,"},{"Start":"04:07.670 ","End":"04:14.595","Text":"this map of where the various sensations are located,"},{"Start":"04:14.595 ","End":"04:20.010","Text":"or the nerves that sense various things where they\u0027re located,"},{"Start":"04:20.010 ","End":"04:22.670","Text":"there\u0027s a map of these things and they\u0027re similar to"},{"Start":"04:22.670 ","End":"04:26.173","Text":"the motor cortex that we described a few minutes ago,"},{"Start":"04:26.173 ","End":"04:28.795","Text":"and was labeled in red."},{"Start":"04:28.795 ","End":"04:34.345","Text":"Now, we\u0027re going to look at something different called the occipital lobe."},{"Start":"04:34.345 ","End":"04:38.040","Text":"This is a lobe, notice that it connects the eyes,"},{"Start":"04:38.040 ","End":"04:39.330","Text":"the front here,"},{"Start":"04:39.330 ","End":"04:41.150","Text":"so it\u0027s going to have to do with vision,"},{"Start":"04:41.150 ","End":"04:43.910","Text":"with the rear of the brain,"},{"Start":"04:43.910 ","End":"04:45.050","Text":"the back of the brain."},{"Start":"04:45.050 ","End":"04:47.810","Text":"It\u0027s going to be involved primarily in,"},{"Start":"04:47.810 ","End":"04:51.590","Text":"of course, vision because we\u0027re talking about the eyes,"},{"Start":"04:51.590 ","End":"04:56.255","Text":"and it\u0027s going to also be involved in processing what the eye see,"},{"Start":"04:56.255 ","End":"04:58.265","Text":"that is seeing, recognizing,"},{"Start":"04:58.265 ","End":"05:01.560","Text":"and identifying the visual world."},{"Start":"05:01.560 ","End":"05:04.530","Text":"That\u0027s going to happen more in the back of the brain."},{"Start":"05:04.530 ","End":"05:06.529","Text":"It integrates visual information,"},{"Start":"05:06.529 ","End":"05:07.960","Text":"things that have to do with color,"},{"Start":"05:07.960 ","End":"05:09.520","Text":"shape, distance,"},{"Start":"05:09.520 ","End":"05:11.490","Text":"and things of that sort."},{"Start":"05:11.490 ","End":"05:17.300","Text":"That will be done in this area called the temporal lobe,"},{"Start":"05:17.300 ","End":"05:21.764","Text":"which is at the base of the brain by the ears,"},{"Start":"05:21.764 ","End":"05:24.345","Text":"over here, as you can see."},{"Start":"05:24.345 ","End":"05:28.070","Text":"It\u0027s involved in processing and interpreting sounds,"},{"Start":"05:28.070 ","End":"05:30.720","Text":"language, speech, and so on."},{"Start":"05:30.720 ","End":"05:34.250","Text":"There is a portion of it called the hippocampus,"},{"Start":"05:34.250 ","End":"05:36.590","Text":"which also processes memory."},{"Start":"05:36.590 ","End":"05:42.830","Text":"There\u0027s memory formation in this region that stores long-term memories,"},{"Start":"05:42.830 ","End":"05:46.565","Text":"and it plays an important role in this spatial processing and navigation."},{"Start":"05:46.565 ","End":"05:53.000","Text":"There\u0027s an integration of the senses that we get together with"},{"Start":"05:53.000 ","End":"06:01.115","Text":"this consolidation of the understanding of these senses so that we generate memories,"},{"Start":"06:01.115 ","End":"06:07.579","Text":"and also integrate them into a spatial processing system."},{"Start":"06:07.579 ","End":"06:11.885","Text":"It\u0027s quite a complicated thing, of course."},{"Start":"06:11.885 ","End":"06:14.245","Text":"In future videos,"},{"Start":"06:14.245 ","End":"06:21.450","Text":"we\u0027ll see how these things are involved also in our movement in motor control."}],"ID":29046},{"Watched":false,"Name":"Mid and hindbrain and their functions","Duration":"5m 53s","ChapterTopicVideoID":27859,"CourseChapterTopicPlaylistID":275102,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.685","Text":"Now let\u0027s look further into the brain below the cortex,"},{"Start":"00:05.685 ","End":"00:08.885","Text":"and look at the basal nuclei,"},{"Start":"00:08.885 ","End":"00:11.340","Text":"as you can see which are really right in"},{"Start":"00:11.340 ","End":"00:14.790","Text":"the center of the brain a little bit further back,"},{"Start":"00:14.790 ","End":"00:23.395","Text":"and then as well can be divided into different regions that have different functions."},{"Start":"00:23.395 ","End":"00:29.805","Text":"This is a group of subcortical nuclei or regions,"},{"Start":"00:29.805 ","End":"00:34.875","Text":"that are in the brain, and they\u0027re responsible primarily for motor control movement."},{"Start":"00:34.875 ","End":"00:37.320","Text":"As we had mentioned in the previous video,"},{"Start":"00:37.320 ","End":"00:39.650","Text":"we\u0027re going to discuss motor movements."},{"Start":"00:39.650 ","End":"00:45.250","Text":"All the things that we felt from the cortex or that we smelled, or we saw,"},{"Start":"00:45.250 ","End":"00:47.255","Text":"or so on, have to be,"},{"Start":"00:47.255 ","End":"00:51.565","Text":"or can be at least translated into movement."},{"Start":"00:51.565 ","End":"00:54.230","Text":"There is a section of the brain,"},{"Start":"00:54.230 ","End":"00:58.685","Text":"this region which is primarily responsible for motor control, motor learning,"},{"Start":"00:58.685 ","End":"01:00.365","Text":"that is how to move,"},{"Start":"01:00.365 ","End":"01:02.650","Text":"as a baby has to learn these things,"},{"Start":"01:02.650 ","End":"01:07.340","Text":"and various executive functions as well as emotions."},{"Start":"01:07.340 ","End":"01:10.070","Text":"Something we haven\u0027t discussed previously."},{"Start":"01:10.070 ","End":"01:16.475","Text":"Now, 1 way that we understand about what parts of the brain are responsible for what,"},{"Start":"01:16.475 ","End":"01:20.575","Text":"are through disease, as I briefly mentioned in an earlier video."},{"Start":"01:20.575 ","End":"01:24.700","Text":"When there is a problem, for instance,"},{"Start":"01:24.700 ","End":"01:26.210","Text":"in the basal nuclei,"},{"Start":"01:26.210 ","End":"01:29.045","Text":"or in the basal ganglia,"},{"Start":"01:29.045 ","End":"01:32.570","Text":"then we can get a disease called Parkinson\u0027s disease,"},{"Start":"01:32.570 ","End":"01:35.240","Text":"which involves damage to this region,"},{"Start":"01:35.240 ","End":"01:38.030","Text":"and we can then see what the impairments are."},{"Start":"01:38.030 ","End":"01:39.050","Text":"As you all know,"},{"Start":"01:39.050 ","End":"01:44.630","Text":"I think Parkinson\u0027s disease results in a person\u0027s posture changing,"},{"Start":"01:44.630 ","End":"01:50.990","Text":"sometimes there is a problem of tremors in the extremities,"},{"Start":"01:50.990 ","End":"01:52.700","Text":"shuffling of feet and so on."},{"Start":"01:52.700 ","End":"01:59.134","Text":"This results from the death of cells in the substantia nigra,"},{"Start":"01:59.134 ","End":"02:05.540","Text":"which is in the region that we\u0027re discussing here and the basal nuclei."},{"Start":"02:05.540 ","End":"02:09.515","Text":"As you can see here, the substantia nigra."},{"Start":"02:09.515 ","End":"02:15.690","Text":"What it leads to is a dopamine deficit."},{"Start":"02:15.690 ","End":"02:19.965","Text":"Dopamine is one of the neurotransmitters at synapses,"},{"Start":"02:19.965 ","End":"02:25.325","Text":"and so there\u0027s a deficits of this neurotransmitter, and in fact,"},{"Start":"02:25.325 ","End":"02:28.250","Text":"although there is no cure known for it,"},{"Start":"02:28.250 ","End":"02:33.095","Text":"one of the things that does help is the drugs which"},{"Start":"02:33.095 ","End":"02:38.810","Text":"will increase the level of dopamine that there is in the brain."},{"Start":"02:38.810 ","End":"02:40.400","Text":"That\u0027s not a cure,"},{"Start":"02:40.400 ","End":"02:42.800","Text":"but at least it\u0027s a help."},{"Start":"02:42.800 ","End":"02:45.680","Text":"Let\u0027s look at other regions here,"},{"Start":"02:45.680 ","End":"02:49.700","Text":"that are in this same part of the brain."},{"Start":"02:49.700 ","End":"02:53.260","Text":"Looking at it it\u0027s a little bit more broadly,"},{"Start":"02:53.260 ","End":"02:55.575","Text":"there is the diencephalon,"},{"Start":"02:55.575 ","End":"02:59.210","Text":"which involves both the thalamus and the limbic system."},{"Start":"02:59.210 ","End":"03:02.585","Text":"This regulates emotion, fear, motivation,"},{"Start":"03:02.585 ","End":"03:06.430","Text":"memory formation, similar to what we saw before."},{"Start":"03:06.430 ","End":"03:10.400","Text":"There is a region called the amygdala,"},{"Start":"03:10.400 ","End":"03:13.850","Text":"a very small region that you can see here down at the bottom of the brain,"},{"Start":"03:13.850 ","End":"03:18.500","Text":"which is involved in processing of memory, decision-making, emotional responses."},{"Start":"03:18.500 ","End":"03:21.620","Text":"A cingulate gyrus, this,"},{"Start":"03:21.620 ","End":"03:24.920","Text":"it helps regulate emotions and pain."},{"Start":"03:24.920 ","End":"03:27.890","Text":"That\u0027s the region which is above over here."},{"Start":"03:27.890 ","End":"03:31.489","Text":"Various parts of the thalamus and hypothalamus as the hippocampus"},{"Start":"03:31.489 ","End":"03:35.750","Text":"have different functions as well."},{"Start":"03:35.750 ","End":"03:39.755","Text":"Now let\u0027s look at the midbrain,"},{"Start":"03:39.755 ","End":"03:45.770","Text":"which is a little bit below the region that we\u0027ve just been talking about."},{"Start":"03:45.770 ","End":"03:52.835","Text":"In the midbrain, which is sometimes considered together with the hindbrain,"},{"Start":"03:52.835 ","End":"03:56.300","Text":"it\u0027s part of it, includes the brainstem."},{"Start":"03:56.300 ","End":"04:00.585","Text":"That\u0027s what\u0027s going to go down into the spinal cord."},{"Start":"04:00.585 ","End":"04:06.420","Text":"It can be further subdivided as you can see here."},{"Start":"04:06.420 ","End":"04:11.180","Text":"What is it? It controls nerve reflexes that"},{"Start":"04:11.180 ","End":"04:13.010","Text":"involve the movement of the neck and the head and"},{"Start":"04:13.010 ","End":"04:15.230","Text":"response to visual and auditory stimuli."},{"Start":"04:15.230 ","End":"04:18.260","Text":"If you see something out of the side of your eye,"},{"Start":"04:18.260 ","End":"04:21.860","Text":"you might turn your head and that might even"},{"Start":"04:21.860 ","End":"04:25.940","Text":"be just a reflex and that\u0027s where all that is controlled."},{"Start":"04:25.940 ","End":"04:28.880","Text":"Also, your eyes move around."},{"Start":"04:28.880 ","End":"04:32.042","Text":"Those are also largely reflexes,"},{"Start":"04:32.042 ","End":"04:33.230","Text":"or if something gets in your eye,"},{"Start":"04:33.230 ","End":"04:36.320","Text":"you might close your eye quickly, that\u0027s a reflex."},{"Start":"04:36.320 ","End":"04:39.080","Text":"You don\u0027t have to think about that or the change in your pupil size."},{"Start":"04:39.080 ","End":"04:44.195","Text":"All those things are controlled in this region of the midbrain."},{"Start":"04:44.195 ","End":"04:48.275","Text":"It acts as a coordinating area between"},{"Start":"04:48.275 ","End":"04:55.303","Text":"the thinking part of the cerebrum of the forebrain,"},{"Start":"04:55.303 ","End":"04:57.950","Text":"and the cerebellum, which is in the back,"},{"Start":"04:57.950 ","End":"05:00.430","Text":"that we have yet to discuss."},{"Start":"05:00.430 ","End":"05:03.180","Text":"Now, what is that cerebellum?"},{"Start":"05:03.180 ","End":"05:08.820","Text":"Well, the cerebellum is the hindbrain and that is located"},{"Start":"05:08.820 ","End":"05:14.475","Text":"at the back of the base of the brain as we saw before,"},{"Start":"05:14.475 ","End":"05:20.915","Text":"and it receives various inputs from various parts of the body,"},{"Start":"05:20.915 ","End":"05:25.490","Text":"and it sends motor impulses from the brain to move"},{"Start":"05:25.490 ","End":"05:31.970","Text":"motor skeletal muscles so that the body can react to the things that it sees,"},{"Start":"05:31.970 ","End":"05:33.785","Text":"feels, and so on."},{"Start":"05:33.785 ","End":"05:36.380","Text":"It also controls balance and coordination."},{"Start":"05:36.380 ","End":"05:40.580","Text":"That\u0027s the movement more than movement."},{"Start":"05:40.580 ","End":"05:41.870","Text":"In the next video,"},{"Start":"05:41.870 ","End":"05:45.980","Text":"we will discuss in greater detail what"},{"Start":"05:45.980 ","End":"05:53.310","Text":"the various parts of the brainstem and how they interact with the cerebellum."}],"ID":29047},{"Watched":false,"Name":"The Brainstem","Duration":"5m 3s","ChapterTopicVideoID":27860,"CourseChapterTopicPlaylistID":275102,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.240","Text":"Now welcome back to what will be"},{"Start":"00:03.240 ","End":"00:06.885","Text":"the last video that discusses the central nervous system."},{"Start":"00:06.885 ","End":"00:12.750","Text":"We will be discussing the brainstem which consists of the mid-brain,"},{"Start":"00:12.750 ","End":"00:16.410","Text":"pons and medulla oblongata."},{"Start":"00:16.410 ","End":"00:22.160","Text":"Here as you can see, this brainstem is subdivided as we subdivided,"},{"Start":"00:22.160 ","End":"00:25.640","Text":"for instance, the cerebrum earlier."},{"Start":"00:25.640 ","End":"00:30.260","Text":"Each of these sections has different functions, not surprisingly."},{"Start":"00:30.260 ","End":"00:34.325","Text":"The midbrain over here acts as"},{"Start":"00:34.325 ","End":"00:37.460","Text":"a relay station for tracts passing"},{"Start":"00:37.460 ","End":"00:41.165","Text":"between the cerebrum and the spinal cord or cerebellum."},{"Start":"00:41.165 ","End":"00:46.635","Text":"This is a transit point for different signals."},{"Start":"00:46.635 ","End":"00:52.084","Text":"The pons, it\u0027s just below it helps in something very important."},{"Start":"00:52.084 ","End":"00:54.320","Text":"It regulates breathing and head movements."},{"Start":"00:54.320 ","End":"00:59.635","Text":"These are things you\u0027ll notice which are involuntary for the most part."},{"Start":"00:59.635 ","End":"01:04.460","Text":"This region, the pons regulates those functions."},{"Start":"01:04.460 ","End":"01:11.610","Text":"The medulla oblongata regulates other functions that are also not conscious,"},{"Start":"01:11.610 ","End":"01:14.045","Text":"things like respiration, heart rate,"},{"Start":"01:14.045 ","End":"01:15.720","Text":"vomiting sometimes which,"},{"Start":"01:15.720 ","End":"01:18.290","Text":"of course you know can be involuntary,"},{"Start":"01:18.290 ","End":"01:19.835","Text":"coughing, and so on."},{"Start":"01:19.835 ","End":"01:25.445","Text":"These are various reflexes that are in the brainstem that are more basic."},{"Start":"01:25.445 ","End":"01:28.220","Text":"They\u0027re not so much involved in thinking,"},{"Start":"01:28.220 ","End":"01:35.795","Text":"but they involve movements in the body that are essential for its function."},{"Start":"01:35.795 ","End":"01:39.770","Text":"Now let\u0027s continue and look at the spinal cord."},{"Start":"01:39.770 ","End":"01:44.010","Text":"The spinal cord, which moves down the back of"},{"Start":"01:44.010 ","End":"01:51.470","Text":"our body and which as we mentioned earlier is connected very much with the brain,"},{"Start":"01:51.470 ","End":"01:55.065","Text":"and remember there\u0027s the spinal fluid which,"},{"Start":"01:55.065 ","End":"01:56.565","Text":"moves back and forth."},{"Start":"01:56.565 ","End":"02:00.175","Text":"It circulates between the brain and the spine."},{"Start":"02:00.175 ","End":"02:06.260","Text":"In addition, we have lots of nerves which go down from the brain and are"},{"Start":"02:06.260 ","End":"02:09.260","Text":"going to control the movements in the rest of"},{"Start":"02:09.260 ","End":"02:13.590","Text":"the body and also receive sensations from there."},{"Start":"02:14.140 ","End":"02:19.550","Text":"The nerves there are contained within the bones of the vertebral column and they"},{"Start":"02:19.550 ","End":"02:24.710","Text":"transmit this information back and forth between the body and the brain."},{"Start":"02:24.710 ","End":"02:28.560","Text":"It contains 2 different kinds of matter"},{"Start":"02:28.560 ","End":"02:32.420","Text":"when you look at them: There\u0027s what\u0027s called gray matter and white matter."},{"Start":"02:32.420 ","End":"02:34.625","Text":"The gray matter, that\u0027s the color of it,"},{"Start":"02:34.625 ","End":"02:37.010","Text":"contains the neurons, cell bodies, dendrites,"},{"Start":"02:37.010 ","End":"02:42.395","Text":"unmyelinated axons, and the white matter is going to be this myelin."},{"Start":"02:42.395 ","End":"02:48.890","Text":"Remember myelin is an insulator and we see that there are these bundles of axons that are"},{"Start":"02:48.890 ","End":"02:52.460","Text":"myelinated and that\u0027s what gives us the white matter and they\u0027re"},{"Start":"02:52.460 ","End":"02:56.840","Text":"separated in different parts of the spine."},{"Start":"02:56.840 ","End":"03:01.100","Text":"This is a cross-section of the spinal cord and you can see the gray matter and"},{"Start":"03:01.100 ","End":"03:05.880","Text":"white matter are not in the same positions exactly."},{"Start":"03:05.880 ","End":"03:07.685","Text":"In the spinal cord,"},{"Start":"03:07.685 ","End":"03:12.005","Text":"we have axons and cell bodies on the dorsal side,"},{"Start":"03:12.005 ","End":"03:14.150","Text":"and they convey mostly sensory information,"},{"Start":"03:14.150 ","End":"03:18.650","Text":"s that\u0027s the sensory information from the body that goes to the brain,"},{"Start":"03:18.650 ","End":"03:22.190","Text":"as we can see here is a sensory neuron and then they\u0027re going to be"},{"Start":"03:22.190 ","End":"03:28.580","Text":"motor neurons down here that are going to be involved in movement."},{"Start":"03:28.580 ","End":"03:30.980","Text":"We have both sensory,"},{"Start":"03:30.980 ","End":"03:33.190","Text":"and motor neurons,"},{"Start":"03:33.190 ","End":"03:36.845","Text":"and they are going to be coordinated of course,"},{"Start":"03:36.845 ","End":"03:39.590","Text":"because they\u0027re of course is the sensing of"},{"Start":"03:39.590 ","End":"03:44.014","Text":"information and then there is the movement in response."},{"Start":"03:44.014 ","End":"03:49.640","Text":"In fact, some of these sensations don\u0027t even get to the brain at all."},{"Start":"03:49.640 ","End":"03:51.845","Text":"There\u0027s a reflex arc,"},{"Start":"03:51.845 ","End":"03:54.275","Text":"so that if you touch something very hot,"},{"Start":"03:54.275 ","End":"03:59.660","Text":"you move your hands very quickly without your brain being involved at all."},{"Start":"03:59.660 ","End":"04:02.510","Text":"There are pain receptors in the skin and the"},{"Start":"04:02.510 ","End":"04:05.510","Text":"sensation moves directly to the spinal cord,"},{"Start":"04:05.510 ","End":"04:08.510","Text":"and then there are motor neurons which then"},{"Start":"04:08.510 ","End":"04:11.750","Text":"innervates the muscles to move your hand away."},{"Start":"04:11.750 ","End":"04:15.380","Text":"Only after that does it get to the brain."},{"Start":"04:15.380 ","End":"04:21.190","Text":"There are these quick unconscious movements and they are fast because they\u0027re local,"},{"Start":"04:21.190 ","End":"04:24.725","Text":"you don\u0027t have long distances for the signal to travel."},{"Start":"04:24.725 ","End":"04:29.660","Text":"They may require only 1 or 2 synapses."},{"Start":"04:29.660 ","End":"04:35.610","Text":"Of course, a synapses between the nerves are going to be the slope point of movements."},{"Start":"04:35.610 ","End":"04:41.555","Text":"After that, information is transmitted to the brain."},{"Start":"04:41.555 ","End":"04:46.355","Text":"I hope you\u0027ve enjoyed the discussion of the central nervous system."},{"Start":"04:46.355 ","End":"04:48.110","Text":"In our next videos,"},{"Start":"04:48.110 ","End":"04:52.460","Text":"we\u0027re going to be looking at the peripheral nervous system,"},{"Start":"04:52.460 ","End":"04:57.709","Text":"which is going to control the movements that are farther"},{"Start":"04:57.709 ","End":"05:03.840","Text":"away from the brain and some of them are going to be unconscious."}],"ID":29048}],"Thumbnail":null,"ID":275102},{"Name":"The Peripheral Nervous System","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"The Sympathetic Nervous System","Duration":"6m 45s","ChapterTopicVideoID":27856,"CourseChapterTopicPlaylistID":275103,"HasSubtitles":true,"ThumbnailPath":"https://www.proprep.uk/Images/Videos_Thumbnails/27856.jpeg","UploadDate":"2021-12-09T14:29:04.5500000","DurationForVideoObject":"PT6M45S","Description":null,"MetaTitle":"The Sympathetic Nervous System: Video + Workbook | Proprep","MetaDescription":"The Nervous System - The Peripheral Nervous System. 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-nervous-system/the-peripheral-nervous-system/vid29049","VideoComments":[],"Subtitles":[{"Start":"00:00.020 ","End":"00:03.975","Text":"We\u0027ve been talking about the nervous system,"},{"Start":"00:03.975 ","End":"00:05.535","Text":"and in the previous videos,"},{"Start":"00:05.535 ","End":"00:10.455","Text":"we discussed the central nervous system, the CNS."},{"Start":"00:10.455 ","End":"00:17.580","Text":"Now we\u0027re going to be talking about the peripheral nervous system or the PNS."},{"Start":"00:17.580 ","End":"00:23.940","Text":"The central nervous system was really where all the thinking went on."},{"Start":"00:23.940 ","End":"00:29.585","Text":"If you remember the connection between sites and action,"},{"Start":"00:29.585 ","End":"00:32.570","Text":"or different sensations and action,"},{"Start":"00:32.570 ","End":"00:36.830","Text":"or the way the brain control various organs in the body."},{"Start":"00:36.830 ","End":"00:41.285","Text":"But all that of course has to be wired somehow to the rest of the body."},{"Start":"00:41.285 ","End":"00:45.410","Text":"That is the peripheral nervous system,"},{"Start":"00:45.410 ","End":"00:49.325","Text":"which is the connection between the central nervous system,"},{"Start":"00:49.325 ","End":"00:51.430","Text":"and the rest of the body."},{"Start":"00:51.430 ","End":"00:57.020","Text":"That connection is actually made of 2 different kinds of neurons."},{"Start":"00:57.020 ","End":"01:00.485","Text":"There are the afferent neurons,"},{"Start":"01:00.485 ","End":"01:06.100","Text":"those are the ones that transmit information to the central nervous system."},{"Start":"01:06.100 ","End":"01:09.480","Text":"You can see it over here, the afferent neurons,"},{"Start":"01:09.480 ","End":"01:13.100","Text":"and there are the efferent neurons."},{"Start":"01:13.100 ","End":"01:15.200","Text":"Those are those here,"},{"Start":"01:15.200 ","End":"01:19.355","Text":"that transmit information away from the central nervous system."},{"Start":"01:19.355 ","End":"01:22.075","Text":"In other words, from the brain."},{"Start":"01:22.075 ","End":"01:25.405","Text":"They transmit away from the brain the efferent,"},{"Start":"01:25.405 ","End":"01:29.150","Text":"and the afferent transmit to the brain,"},{"Start":"01:29.150 ","End":"01:32.465","Text":"as you can see with this arrow over here."},{"Start":"01:32.465 ","End":"01:35.790","Text":"They contain 2 components."},{"Start":"01:35.790 ","End":"01:38.720","Text":"That is, the efferent contains 2 different neurons."},{"Start":"01:38.720 ","End":"01:42.215","Text":"As you can see, there\u0027s the autonomic nervous system."},{"Start":"01:42.215 ","End":"01:45.568","Text":"That\u0027s the things that happen pretty much automatically,"},{"Start":"01:45.568 ","End":"01:48.700","Text":"and the motor system."},{"Start":"01:48.700 ","End":"01:52.340","Text":"The autonomic nervous system regulates smooth in cardiac muscles,"},{"Start":"01:52.340 ","End":"01:54.485","Text":"things that are involuntary,"},{"Start":"01:54.485 ","End":"01:58.220","Text":"and the motor system is what controls our muscles,"},{"Start":"01:58.220 ","End":"02:02.105","Text":"things we move, and that carries signals to the skeletal muscles."},{"Start":"02:02.105 ","End":"02:06.770","Text":"As I said, can be voluntary, usually is voluntary."},{"Start":"02:06.770 ","End":"02:08.360","Text":"Now in addition to that,"},{"Start":"02:08.360 ","End":"02:13.895","Text":"there is an enteric nervous system that you can see as part of the efferent neurons."},{"Start":"02:13.895 ","End":"02:16.310","Text":"They exert direct control over things like"},{"Start":"02:16.310 ","End":"02:19.970","Text":"the digestive tract, the pancreas, gallbladder,"},{"Start":"02:19.970 ","End":"02:23.765","Text":"other things that happen pretty much automatically,"},{"Start":"02:23.765 ","End":"02:26.975","Text":"but they are in response to"},{"Start":"02:26.975 ","End":"02:33.815","Text":"external stimuli that can change the way these various systems work."},{"Start":"02:33.815 ","End":"02:44.225","Text":"Let\u0027s now look at the autonomic nervous system in more detail."},{"Start":"02:44.225 ","End":"02:48.140","Text":"It innervates all the internal organs."},{"Start":"02:48.140 ","End":"02:52.039","Text":"Here you can see all these various internal organs,"},{"Start":"02:52.039 ","End":"02:53.900","Text":"and they are innervated."},{"Start":"02:53.900 ","End":"02:57.875","Text":"That is, there are nerves that connect them"},{"Start":"02:57.875 ","End":"03:02.795","Text":"to the brain through the spinal cord and it innervates."},{"Start":"03:02.795 ","End":"03:05.944","Text":"All of these organs are innervated,"},{"Start":"03:05.944 ","End":"03:09.985","Text":"and they use 2 different kinds of neurons."},{"Start":"03:09.985 ","End":"03:13.910","Text":"There are 2 neurons that go into each of them."},{"Start":"03:13.910 ","End":"03:20.270","Text":"You can see one from the left and one from the right, and one ganglion."},{"Start":"03:20.270 ","End":"03:24.810","Text":"The ganglion is in the spinal cord."},{"Start":"03:24.810 ","End":"03:31.015","Text":"They are divided into 2 different neurons."},{"Start":"03:31.015 ","End":"03:33.965","Text":"There is sympathetic division,"},{"Start":"03:33.965 ","End":"03:36.080","Text":"those that regulate arousal,"},{"Start":"03:36.080 ","End":"03:39.830","Text":"energy generation, that\u0027s like the fight or flight."},{"Start":"03:39.830 ","End":"03:40.910","Text":"What happens when you see,"},{"Start":"03:40.910 ","End":"03:44.870","Text":"let\u0027s say a snake, sympathetic snake."},{"Start":"03:44.870 ","End":"03:46.610","Text":"You can see it\u0027s easy to remember that way."},{"Start":"03:46.610 ","End":"03:54.260","Text":"There are the parasympathetic nerves and those do exactly the opposite."},{"Start":"03:54.260 ","End":"03:55.760","Text":"You can see, for instance,"},{"Start":"03:55.760 ","End":"04:00.440","Text":"on this side we have the sympathetic ones accelerates the heartbeat,"},{"Start":"04:00.440 ","End":"04:04.310","Text":"and there\u0027s others that slow the heartbeat."},{"Start":"04:04.310 ","End":"04:09.805","Text":"So it\u0027ll be the parasympathetic which would be slowing the heartbeat."},{"Start":"04:09.805 ","End":"04:15.915","Text":"These things are opposite in opposing ways."},{"Start":"04:15.915 ","End":"04:21.110","Text":"Now, let\u0027s look first at the sympathetic nervous system."},{"Start":"04:21.110 ","End":"04:28.145","Text":"Those are mostly preganglionic neurons that originate in the spinal cord,"},{"Start":"04:28.145 ","End":"04:32.985","Text":"and they then innervate to the various organs."},{"Start":"04:32.985 ","End":"04:34.670","Text":"They for the most part,"},{"Start":"04:34.670 ","End":"04:42.005","Text":"use acetylcholine as the neurotransmitter on the postganglionic neurons."},{"Start":"04:42.005 ","End":"04:43.745","Text":"There is a synapse."},{"Start":"04:43.745 ","End":"04:49.399","Text":"There\u0027s a preganglionic neuron and a postganglionic neuron within"},{"Start":"04:49.399 ","End":"04:55.425","Text":"the sympathetic ganglia and those extend alongside the spinal cord over here."},{"Start":"04:55.425 ","End":"05:03.500","Text":"There\u0027s this sympathetic chain that controls the impulses to the different organs."},{"Start":"05:03.500 ","End":"05:09.470","Text":"They release primarily norepinephrine onto the target organisms."},{"Start":"05:09.470 ","End":"05:11.525","Text":"You can see norepinephrine here,"},{"Start":"05:11.525 ","End":"05:13.370","Text":"neurons are marked in blue,"},{"Start":"05:13.370 ","End":"05:15.950","Text":"and as you can see most of them are blue,"},{"Start":"05:15.950 ","End":"05:20.640","Text":"the ones that are part of the sympathetic nervous system."},{"Start":"05:20.640 ","End":"05:25.430","Text":"They amplify the effects of the impulse because"},{"Start":"05:25.430 ","End":"05:32.810","Text":"1 preganglionic neuron synapse can then affect multiple postganglionic neurons."},{"Start":"05:32.810 ","End":"05:40.790","Text":"So 1 preganglionic neuron will connect with multiple postganglionic neurons,"},{"Start":"05:40.790 ","End":"05:44.330","Text":"and therefore the signal can be amplified."},{"Start":"05:44.330 ","End":"05:47.750","Text":"The adrenal glands, which is in the brain,"},{"Start":"05:47.750 ","End":"05:52.100","Text":"also releases norepinephrine into the bloodstream at"},{"Start":"05:52.100 ","End":"05:57.005","Text":"the same time in order to create this arousal."},{"Start":"05:57.005 ","End":"06:03.110","Text":"Now the strength and speed of the sympathetic response helps the organism avoid danger."},{"Start":"06:03.110 ","End":"06:04.940","Text":"If you suddenly, for instance,"},{"Start":"06:04.940 ","End":"06:06.140","Text":"were to see a snake,"},{"Start":"06:06.140 ","End":"06:10.270","Text":"then all these various things would be affected,"},{"Start":"06:10.270 ","End":"06:14.150","Text":"and in the ways that are described here in this figure,"},{"Start":"06:14.150 ","End":"06:21.380","Text":"and you would be ready now to either fight or flee from this snake."},{"Start":"06:21.380 ","End":"06:22.820","Text":"In addition to all these,"},{"Start":"06:22.820 ","End":"06:27.545","Text":"there also may be long-term potentiation, LTP, that is,"},{"Start":"06:27.545 ","End":"06:30.950","Text":"the animal could remember the dangerous situation so that"},{"Start":"06:30.950 ","End":"06:34.445","Text":"it will react more quickly in the future."},{"Start":"06:34.445 ","End":"06:37.940","Text":"That was the sympathetic nervous system."},{"Start":"06:37.940 ","End":"06:39.335","Text":"In the next video,"},{"Start":"06:39.335 ","End":"06:45.120","Text":"we\u0027ll be describing the parasympathetic nervous system."}],"ID":29049},{"Watched":false,"Name":"The Parasympathetic Nervous System","Duration":"5m 29s","ChapterTopicVideoID":27855,"CourseChapterTopicPlaylistID":275103,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.100","Text":"Welcome back to the discussion of the peripheral nervous system, or the PNS."},{"Start":"00:06.100 ","End":"00:07.870","Text":"In the previous video,"},{"Start":"00:07.870 ","End":"00:11.530","Text":"we discussed the sympathetic nervous system,"},{"Start":"00:11.530 ","End":"00:16.330","Text":"which you\u0027ll remember is the fight or flight, the arousal system."},{"Start":"00:16.330 ","End":"00:25.030","Text":"The parasympathetic system is the opposite and it allows the animal to rest and digest."},{"Start":"00:25.030 ","End":"00:32.260","Text":"That is to figure out what to do in the particular situation it might find itself."},{"Start":"00:32.260 ","End":"00:36.820","Text":"There are preganglionic neurons that have cell bodies which are"},{"Start":"00:36.820 ","End":"00:42.810","Text":"located now in the brainstem and in the sacral spinal cord."},{"Start":"00:42.810 ","End":"00:46.140","Text":"Remember the brainstem which is up here."},{"Start":"00:46.140 ","End":"00:51.335","Text":"Those are found in the brainstem,"},{"Start":"00:51.335 ","End":"00:54.200","Text":"as I said and they from there we\u0027ll go to"},{"Start":"00:54.200 ","End":"00:57.845","Text":"the various organs as opposed to the ones that we saw earlier,"},{"Start":"00:57.845 ","End":"01:05.645","Text":"which came from the spinal cord itself or adjacent to the spinal cord."},{"Start":"01:05.645 ","End":"01:13.595","Text":"In this case, they use acetylcholine for the postganglionic neurons,"},{"Start":"01:13.595 ","End":"01:20.810","Text":"and they\u0027re generally located very near the target organs, these synapses."},{"Start":"01:20.810 ","End":"01:24.200","Text":"Most postganglionic neurons release acetylcholine,"},{"Start":"01:24.200 ","End":"01:27.510","Text":"as we said, onto their target organs themselves."},{"Start":"01:27.510 ","End":"01:32.840","Text":"As you can see here these are these yellowish orangish lines that"},{"Start":"01:32.840 ","End":"01:39.440","Text":"denotes acetylcholine as opposed to the blue ones that were the norepinephrine."},{"Start":"01:39.440 ","End":"01:45.110","Text":"These reset the organ function after the sympathetic nervous system is activated."},{"Start":"01:45.110 ","End":"01:48.980","Text":"After arousal, then the return to"},{"Start":"01:48.980 ","End":"01:55.020","Text":"the normal state is mediated by the parasympathetic nervous system."},{"Start":"01:55.020 ","End":"01:59.330","Text":"Now let\u0027s look at the sensory somatic nervous system."},{"Start":"01:59.330 ","End":"02:04.670","Text":"Another nervous system, which is part of the peripheral nervous system."},{"Start":"02:04.670 ","End":"02:08.435","Text":"This is made up of both cranial and spinal nerves,"},{"Start":"02:08.435 ","End":"02:13.195","Text":"and they contain both sensory and motor neurons."},{"Start":"02:13.195 ","End":"02:15.680","Text":"You\u0027ll remember that there are sense,"},{"Start":"02:15.680 ","End":"02:21.334","Text":"there\u0027s a sensory cortex and the motor cortex which are in the cerebrum."},{"Start":"02:21.334 ","End":"02:28.130","Text":"They then send nerves out to the spinal cord and"},{"Start":"02:28.130 ","End":"02:34.760","Text":"then into the various organs to either sense something or to move muscles,"},{"Start":"02:34.760 ","End":"02:40.175","Text":"depending on whether they\u0027re more motor neurons or sensory neurons."},{"Start":"02:40.175 ","End":"02:44.255","Text":"Yes. So they transmit sensory information from the skin,"},{"Start":"02:44.255 ","End":"02:47.420","Text":"skeletal muscle, and sensory organs to the central nervous system."},{"Start":"02:47.420 ","End":"02:53.314","Text":"So you have a sense that goes up into the sensory cortex and then motor neurons,"},{"Start":"02:53.314 ","End":"02:59.720","Text":"then will transmit appropriate messages from that CNS to the muscles themselves."},{"Start":"02:59.720 ","End":"03:04.370","Text":"The CNS and the target organisms are connected with each other,"},{"Start":"03:04.370 ","End":"03:09.080","Text":"interestingly, only through 1 synapse."},{"Start":"03:09.080 ","End":"03:10.640","Text":"Now, what are the neurotransmitters?"},{"Start":"03:10.640 ","End":"03:17.330","Text":"So acetylcholine is the main neurotransmitter released at both these synapses."},{"Start":"03:17.330 ","End":"03:21.380","Text":"Now let\u0027s look to see which nerves we\u0027re talking about."},{"Start":"03:21.380 ","End":"03:24.110","Text":"They\u0027d go through here. How many of these nervous are there?"},{"Start":"03:24.110 ","End":"03:29.435","Text":"Well, the nerves that emerge from the skull are actually rather limited."},{"Start":"03:29.435 ","End":"03:33.785","Text":"There are only about 12 such nerves."},{"Start":"03:33.785 ","End":"03:38.155","Text":"Some of the cranial nerves transmit only sensory information,"},{"Start":"03:38.155 ","End":"03:40.250","Text":"like for instance, the olfactory nerve,"},{"Start":"03:40.250 ","End":"03:42.410","Text":"that\u0027s the one we use for smell."},{"Start":"03:42.410 ","End":"03:45.980","Text":"Others transmit only motor information."},{"Start":"03:45.980 ","End":"03:49.580","Text":"So for instance, those that control eye movements."},{"Start":"03:49.580 ","End":"03:53.915","Text":"Others contain both, as you can see over here."},{"Start":"03:53.915 ","End":"03:57.275","Text":"Now let\u0027s look at the spinal nerves,"},{"Start":"03:57.275 ","End":"03:59.150","Text":"the ones that are in the spine."},{"Start":"03:59.150 ","End":"04:01.200","Text":"This is a cross-section of the spine."},{"Start":"04:01.200 ","End":"04:03.800","Text":"They transmit sensory and motor information"},{"Start":"04:03.800 ","End":"04:07.070","Text":"between the spinal cord and the rest of the body."},{"Start":"04:07.070 ","End":"04:09.475","Text":"So again, the spinal cord."},{"Start":"04:09.475 ","End":"04:14.795","Text":"There can be both sensory neurons."},{"Start":"04:14.795 ","End":"04:18.860","Text":"Yes, and there are the motor ones."},{"Start":"04:18.860 ","End":"04:21.050","Text":"So the sensory neuron cell bodies,"},{"Start":"04:21.050 ","End":"04:25.825","Text":"they\u0027re grouped in this area called the dorsal root ganglia."},{"Start":"04:25.825 ","End":"04:30.560","Text":"There is the sensory neurons in which there\u0027s 1 projection with"},{"Start":"04:30.560 ","End":"04:36.670","Text":"sensory receptor and another that has a synapse with a neuron in the dorsal spinal cord."},{"Start":"04:36.670 ","End":"04:38.615","Text":"Here you can see, for instance,"},{"Start":"04:38.615 ","End":"04:42.500","Text":"these different neurons, a sensory neuron,"},{"Start":"04:42.500 ","End":"04:47.090","Text":"which is then connected to the motor neuron,"},{"Start":"04:47.090 ","End":"04:49.910","Text":"which is going to produce a signal."},{"Start":"04:49.910 ","End":"04:54.470","Text":"So the sensory neuron comes into the spine"},{"Start":"04:54.470 ","End":"04:59.570","Text":"and then there\u0027s a motor neuron that goes right out without ever getting into the brain."},{"Start":"04:59.570 ","End":"05:02.555","Text":"Now if we look at these nerves,"},{"Start":"05:02.555 ","End":"05:06.320","Text":"then we can see that some of them,"},{"Start":"05:06.320 ","End":"05:10.160","Text":"there is gray matter and there is white matter."},{"Start":"05:10.160 ","End":"05:12.395","Text":"So the motor neurons, it turns out,"},{"Start":"05:12.395 ","End":"05:16.520","Text":"are located in the gray matter of the spinal cord."},{"Start":"05:16.520 ","End":"05:22.550","Text":"They project to the muscle through this what\u0027s called the ventral root."},{"Start":"05:22.550 ","End":"05:29.160","Text":"That\u0027s this projection that comes out of the spinal cord."}],"ID":29050},{"Watched":false,"Name":"Disease of The Nervous System","Duration":"7m 12s","ChapterTopicVideoID":27857,"CourseChapterTopicPlaylistID":275103,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.215","Text":"I\u0027m glad you\u0027re back for the last videos that describe"},{"Start":"00:04.215 ","End":"00:10.785","Text":"the various disorders or some of the disorders which can occur in the nervous system."},{"Start":"00:10.785 ","End":"00:13.335","Text":"Of course, the nervous system,"},{"Start":"00:13.335 ","End":"00:16.530","Text":"which functions correctly is truly amazing,"},{"Start":"00:16.530 ","End":"00:21.870","Text":"it is so complicated as you saw in the previous videos."},{"Start":"00:21.870 ","End":"00:29.130","Text":"Well, there are various ways though that a diagnostician can look at a problem at"},{"Start":"00:29.130 ","End":"00:32.070","Text":"a person who has cognitive problems or"},{"Start":"00:32.070 ","End":"00:36.660","Text":"motor problems and so on and try to figure out what\u0027s gone wrong in the brain."},{"Start":"00:36.660 ","End":"00:39.480","Text":"Of course, there are various imaging, techniques;"},{"Start":"00:39.480 ","End":"00:41.615","Text":"CTs and MRIs and so on,"},{"Start":"00:41.615 ","End":"00:44.240","Text":"that can look at what\u0027s going on in the brain."},{"Start":"00:44.240 ","End":"00:45.860","Text":"In addition to that,"},{"Start":"00:45.860 ","End":"00:50.090","Text":"there is also the possibility of looking at the various brainwaves"},{"Start":"00:50.090 ","End":"00:54.485","Text":"that are going on in the brain by attaching electrodes."},{"Start":"00:54.485 ","End":"00:59.149","Text":"For instance, people who are awake or have mental activity"},{"Start":"00:59.149 ","End":"01:04.175","Text":"will have different kinds of brainwave patterns than those who,"},{"Start":"01:04.175 ","End":"01:08.230","Text":"let\u0027s say are sleeping or in very deep sleep."},{"Start":"01:08.230 ","End":"01:12.710","Text":"Unfortunately, there are millions of people in"},{"Start":"01:12.710 ","End":"01:17.040","Text":"this world who have some nervous system disorders."},{"Start":"01:17.040 ","End":"01:21.035","Text":"It\u0027s not that surprising since it\u0027s so complicated."},{"Start":"01:21.035 ","End":"01:25.310","Text":"Of course, there\u0027s ongoing research to seek to find ways"},{"Start":"01:25.310 ","End":"01:29.820","Text":"to better prevent and to treat these disorders."},{"Start":"01:29.820 ","End":"01:33.520","Text":"Now, let\u0027s look at just a few of these disorders."},{"Start":"01:33.520 ","End":"01:37.250","Text":"Alzheimer\u0027s disease, Parkinson\u0027s, Huntington\u0027s, multiple sclerosis."},{"Start":"01:37.250 ","End":"01:42.530","Text":"These are all various diseases which can occur in the brain."},{"Start":"01:42.530 ","End":"01:47.000","Text":"They\u0027re usually caused by the loss of different parts of"},{"Start":"01:47.000 ","End":"01:52.775","Text":"the nervous system that are due to the death of neurons."},{"Start":"01:52.775 ","End":"01:54.470","Text":"As you can see, for instance,"},{"Start":"01:54.470 ","End":"01:59.335","Text":"different diseases will have different areas of the brain that are affected."},{"Start":"01:59.335 ","End":"02:01.610","Text":"In Alzheimer\u0027s disease, for instance,"},{"Start":"02:01.610 ","End":"02:07.640","Text":"this frontal cortex which is marked in blue over here as well as other parts"},{"Start":"02:07.640 ","End":"02:13.774","Text":"of the brain will tend to die and will cause disease."},{"Start":"02:13.774 ","End":"02:19.925","Text":"Unfortunately, usually, these things worsen over time as more and more neurons die."},{"Start":"02:19.925 ","End":"02:25.129","Text":"Now it used to be thought that the neurons that are in the brain cannot regenerate."},{"Start":"02:25.129 ","End":"02:27.785","Text":"But that\u0027s known not to be the case anymore."},{"Start":"02:27.785 ","End":"02:29.870","Text":"But still, in general,"},{"Start":"02:29.870 ","End":"02:35.160","Text":"what is true is that degeneration is usually faster than"},{"Start":"02:35.160 ","End":"02:41.480","Text":"regeneration and therefore situations usually get worse rather than get better."},{"Start":"02:41.480 ","End":"02:46.240","Text":"The particular symptoms that people get are related of course"},{"Start":"02:46.240 ","End":"02:51.130","Text":"to where in the nervous system the death of these neurons occur."},{"Start":"02:51.130 ","End":"02:55.734","Text":"For instance, in Alzheimer\u0027s disease, which causes dementia,"},{"Start":"02:55.734 ","End":"02:58.315","Text":"usually in the elderly patients,"},{"Start":"02:58.315 ","End":"03:00.460","Text":"then there are various parts of the brain,"},{"Start":"03:00.460 ","End":"03:03.700","Text":"as I mentioned before, which die first."},{"Start":"03:03.700 ","End":"03:10.120","Text":"If you look at a healthy brain that you can see here, the Alzheimer\u0027s brain,"},{"Start":"03:10.120 ","End":"03:17.035","Text":"which would be on the right would have enlarged areas where the brain has shrunk."},{"Start":"03:17.035 ","End":"03:18.700","Text":"There\u0027s this atrophy,"},{"Start":"03:18.700 ","End":"03:20.245","Text":"and in addition to that,"},{"Start":"03:20.245 ","End":"03:25.090","Text":"there is a particular kind of pathology"},{"Start":"03:25.090 ","End":"03:30.305","Text":"which can be found in the brains of people who have died of Alzheimer\u0027s disease."},{"Start":"03:30.305 ","End":"03:32.270","Text":"They\u0027ll have, for instance,"},{"Start":"03:32.270 ","End":"03:36.110","Text":"these neurofibril tangles of some"},{"Start":"03:36.110 ","End":"03:41.075","Text":"of their nerves and they are what are called plaques that are found."},{"Start":"03:41.075 ","End":"03:42.320","Text":"Now the symptoms, of course,"},{"Start":"03:42.320 ","End":"03:46.375","Text":"of Alzheimer\u0027s disease are different kinds of dementia."},{"Start":"03:46.375 ","End":"03:49.160","Text":"They\u0027re associated, as I said,"},{"Start":"03:49.160 ","End":"03:52.250","Text":"with the formation of these plaques that are called amyloid plaques,"},{"Start":"03:52.250 ","End":"03:56.390","Text":"these tangles, and the overall shrinking of the brain,"},{"Start":"03:56.390 ","End":"03:57.590","Text":"as we mentioned before."},{"Start":"03:57.590 ","End":"04:00.445","Text":"Unfortunately, there\u0027s no cure at the present."},{"Start":"04:00.445 ","End":"04:05.870","Text":"Parkinson\u0027s disease is another disease of the brain and that causes the loss"},{"Start":"04:05.870 ","End":"04:11.270","Text":"of dopamine neurons in the midbrain in a different area that regulates movement."},{"Start":"04:11.270 ","End":"04:15.080","Text":"Therefore, there are all these various symptoms"},{"Start":"04:15.080 ","End":"04:19.145","Text":"of Parkinson\u0027s disease that most of us are familiar with."},{"Start":"04:19.145 ","End":"04:22.070","Text":"They include shaking of the limb, slowed movements,"},{"Start":"04:22.070 ","End":"04:26.210","Text":"speech changes, the way the person walks like shuffling, and so on."},{"Start":"04:26.210 ","End":"04:31.420","Text":"It results evidentially from a combination of genetic and environmental factors."},{"Start":"04:31.420 ","End":"04:36.445","Text":"But the truth is we don\u0027t really understand where it comes from and unfortunately,"},{"Start":"04:36.445 ","End":"04:38.170","Text":"there is no cure."},{"Start":"04:38.170 ","End":"04:42.145","Text":"But treatment is focused upon easing symptoms,"},{"Start":"04:42.145 ","End":"04:45.355","Text":"usually by giving a drug called L-Dopa,"},{"Start":"04:45.355 ","End":"04:50.830","Text":"which increases the amount of dopamine that is found in the brain."},{"Start":"04:50.830 ","End":"04:57.975","Text":"There are other kinds of disorders that are inborn; neurodevelopmental disorders."},{"Start":"04:57.975 ","End":"05:03.175","Text":"Once the developing embryo developed for one reason or another."},{"Start":"05:03.175 ","End":"05:07.350","Text":"There can be all different phenotypes."},{"Start":"05:07.350 ","End":"05:09.780","Text":"As you can see here, we\u0027re familiar, for instance,"},{"Start":"05:09.780 ","End":"05:14.120","Text":"with down syndrome that often results in slanting of the eyes."},{"Start":"05:14.120 ","End":"05:20.390","Text":"But there are many other kinds of phenotypes that we can see."},{"Start":"05:20.390 ","End":"05:23.840","Text":"There is usually some mental retardation"},{"Start":"05:23.840 ","End":"05:26.570","Text":"in people of this sort and in which the nervous system,"},{"Start":"05:26.570 ","End":"05:29.370","Text":"of course, is disturbed."},{"Start":"05:29.370 ","End":"05:32.030","Text":"That would be intellectual deficits"},{"Start":"05:32.030 ","End":"05:35.255","Text":"and that can lead to problems with communication, learning,"},{"Start":"05:35.255 ","End":"05:40.065","Text":"even motor system problems and often there are"},{"Start":"05:40.065 ","End":"05:46.804","Text":"very complex symptoms and a good example of that is in autism."},{"Start":"05:46.804 ","End":"05:52.440","Text":"In addition, we\u0027re all familiar with mental illness of one form or another."},{"Start":"05:52.440 ","End":"05:57.440","Text":"Those can be disorders that result in problems with thinking,"},{"Start":"05:57.440 ","End":"06:00.890","Text":"with mood, and relating with other people,"},{"Start":"06:00.890 ","End":"06:04.880","Text":"all these various kinds of problems that are involved in"},{"Start":"06:04.880 ","End":"06:10.925","Text":"a personality that can be temporary or they can be longer-lasting."},{"Start":"06:10.925 ","End":"06:13.430","Text":"Some of these disorders and schizophrenia,"},{"Start":"06:13.430 ","End":"06:15.110","Text":"depression, bipolar disorders,"},{"Start":"06:15.110 ","End":"06:16.415","Text":"anxiety, and so on."},{"Start":"06:16.415 ","End":"06:19.040","Text":"There are a number of factors that contribute to these things"},{"Start":"06:19.040 ","End":"06:21.680","Text":"that include genetic predispositions,"},{"Start":"06:21.680 ","End":"06:24.319","Text":"life experiences, brain injury,"},{"Start":"06:24.319 ","End":"06:26.360","Text":"viruses, even toxic chemicals."},{"Start":"06:26.360 ","End":"06:29.600","Text":"It\u0027s not clear exactly what can cause these things."},{"Start":"06:29.600 ","End":"06:32.870","Text":"However, it is possible also that there can be"},{"Start":"06:32.870 ","End":"06:37.460","Text":"other underlying conditions like cancer that can result in changes in the brain."},{"Start":"06:37.460 ","End":"06:40.714","Text":"Of course, none of those things are unusual."},{"Start":"06:40.714 ","End":"06:45.545","Text":"Unfortunately, there are many neurological disorders"},{"Start":"06:45.545 ","End":"06:50.825","Text":"and some of them cannot easily be placed in these various categories."},{"Start":"06:50.825 ","End":"06:53.269","Text":"Those can involve chronic pain conditions,"},{"Start":"06:53.269 ","End":"06:55.070","Text":"various cancers of the nervous system,"},{"Start":"06:55.070 ","End":"06:59.295","Text":"epilepsy disorders, stroke, and so on."},{"Start":"06:59.295 ","End":"07:01.670","Text":"This is just a general,"},{"Start":"07:01.670 ","End":"07:05.780","Text":"very brief overview of some of"},{"Start":"07:05.780 ","End":"07:11.580","Text":"the various disorders that can occur in the nervous system."}],"ID":29051}],"Thumbnail":null,"ID":275103},{"Name":"Exercises","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Exercise 1","Duration":"46s","ChapterTopicVideoID":27846,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:08.625","Text":"Neurons contain which of these things that can receive signals from other neurons?"},{"Start":"00:08.625 ","End":"00:11.085","Text":"Do they contain axons, mitochondria,"},{"Start":"00:11.085 ","End":"00:15.075","Text":"dendrites, or golgi bodies?"},{"Start":"00:15.075 ","End":"00:20.490","Text":"Let\u0027s remember this figure in which there are axons,"},{"Start":"00:20.490 ","End":"00:29.865","Text":"the terminals of which then interact within synapses with potentially dendrites."},{"Start":"00:29.865 ","End":"00:33.740","Text":"The dendrites are going to be receiving the signal and"},{"Start":"00:33.740 ","End":"00:39.650","Text":"the axon is going to be sending the signal from the cell body."},{"Start":"00:39.650 ","End":"00:43.415","Text":"It\u0027s not mitochondria, it\u0027s not golgi bodies,"},{"Start":"00:43.415 ","End":"00:46.710","Text":"it\u0027s got to be dendrites."}],"ID":29019},{"Watched":false,"Name":"Exercise 2","Duration":"51s","ChapterTopicVideoID":27847,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.060","Text":"A something neuron. In other words,"},{"Start":"00:03.060 ","End":"00:10.665","Text":"what neuron has 1 axon and 1 dendrite extending directly from the cell body?"},{"Start":"00:10.665 ","End":"00:12.855","Text":"Is it unipolar?"},{"Start":"00:12.855 ","End":"00:16.440","Text":"That doesn\u0027t seem to make too much sense because we\u0027re talking about"},{"Start":"00:16.440 ","End":"00:20.760","Text":"2 different parts that extend from the cell body."},{"Start":"00:20.760 ","End":"00:24.345","Text":"There is 1 axon and 1 dendrite."},{"Start":"00:24.345 ","End":"00:26.355","Text":"Would it be bipolar?"},{"Start":"00:26.355 ","End":"00:28.365","Text":"Bi means 2, that sounds good."},{"Start":"00:28.365 ","End":"00:33.225","Text":"Multipolar, several, or pseudo unipolar."},{"Start":"00:33.225 ","End":"00:35.040","Text":"Well, quite clearly,"},{"Start":"00:35.040 ","End":"00:37.335","Text":"it\u0027s going to be bipolar."},{"Start":"00:37.335 ","End":"00:39.960","Text":"If you remember this figure,"},{"Start":"00:39.960 ","End":"00:47.215","Text":"the bipolar neuron has both an axon and a dendrite."},{"Start":"00:47.215 ","End":"00:51.330","Text":"We\u0027re talking about a bipolar neuron."}],"ID":29020},{"Watched":false,"Name":"Exercise 3","Duration":"42s","ChapterTopicVideoID":27848,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.015","Text":"Glia that provide myelin for neurons in the brain are called what?"},{"Start":"00:06.015 ","End":"00:08.280","Text":"These glia that provide myelin,"},{"Start":"00:08.280 ","End":"00:10.590","Text":"in other words, they\u0027re making myelin."},{"Start":"00:10.590 ","End":"00:12.465","Text":"Are they schwann cells,"},{"Start":"00:12.465 ","End":"00:18.060","Text":"or oligodendrocytes, microglia, or astrocytes?"},{"Start":"00:18.060 ","End":"00:21.030","Text":"Let\u0027s recall this figure."},{"Start":"00:21.030 ","End":"00:25.560","Text":"This figure, we see that it is the oligodendrocytes,"},{"Start":"00:25.560 ","End":"00:29.415","Text":"which are making the myelin."},{"Start":"00:29.415 ","End":"00:33.825","Text":"Here\u0027s the myelin, this blue in this figure,"},{"Start":"00:33.825 ","End":"00:35.033","Text":"that\u0027s the myelin,"},{"Start":"00:35.033 ","End":"00:38.670","Text":"and it\u0027s the oligodendrocytes that are making it."},{"Start":"00:38.670 ","End":"00:42.370","Text":"Oligodendrocytes. None of the others."}],"ID":29021},{"Watched":false,"Name":"Exercise 4","Duration":"40s","ChapterTopicVideoID":27849,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.060","Text":"For a neuron to fire an action potential,"},{"Start":"00:03.060 ","End":"00:07.365","Text":"its membrane must reach hyperpolarization,"},{"Start":"00:07.365 ","End":"00:11.790","Text":"the threshold of excitation, the refractory period,"},{"Start":"00:11.790 ","End":"00:17.198","Text":"or the inhibitory postsynaptic potential?"},{"Start":"00:17.198 ","End":"00:22.050","Text":"If you remember, the action potential sometimes is"},{"Start":"00:22.050 ","End":"00:28.860","Text":"low and sometimes it rises above a particular threshold."},{"Start":"00:28.860 ","End":"00:36.015","Text":"Only when it reaches that threshold is there a stimulus which occurs,"},{"Start":"00:36.015 ","End":"00:40.630","Text":"so it\u0027s going to be this threshold of excitation."}],"ID":29022},{"Watched":false,"Name":"Exercise 5","Duration":"1m 3s","ChapterTopicVideoID":27850,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.670","Text":"After an action potential,"},{"Start":"00:02.670 ","End":"00:06.510","Text":"the opening of additional voltage-gated, what channels?"},{"Start":"00:06.510 ","End":"00:07.980","Text":"Are they going to be sodium, potassium,"},{"Start":"00:07.980 ","End":"00:10.095","Text":"calcium, or chloride channels?"},{"Start":"00:10.095 ","End":"00:15.000","Text":"The opening of these voltage-gated channels and then the inactivation"},{"Start":"00:15.000 ","End":"00:20.310","Text":"of the sodium channels cause the membrane to return to its resting membrane potential."},{"Start":"00:20.310 ","End":"00:21.810","Text":"We\u0027re being asked now,"},{"Start":"00:21.810 ","End":"00:26.460","Text":"what channels need to open in"},{"Start":"00:26.460 ","End":"00:31.735","Text":"order to cause the membrane to return to its resting membrane potential?"},{"Start":"00:31.735 ","End":"00:34.905","Text":"Let\u0027s recall this figure."},{"Start":"00:34.905 ","End":"00:36.520","Text":"In this figure,"},{"Start":"00:36.520 ","End":"00:45.015","Text":"you can see that there are the sodium channels and there are the potassium channels."},{"Start":"00:45.015 ","End":"00:48.245","Text":"What has to happen in this case, of course,"},{"Start":"00:48.245 ","End":"00:53.750","Text":"is that potassium needs to return out of"},{"Start":"00:53.750 ","End":"00:59.510","Text":"the cell in order to return it to its resting potential."},{"Start":"00:59.510 ","End":"01:04.320","Text":"The answer will be potassium as you can see here."}],"ID":29023},{"Watched":false,"Name":"Exercise 6","Duration":"1m 14s","ChapterTopicVideoID":27851,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:07.230","Text":"What is the term for protein channels that connect 2 neurons at an electrical synapse?"},{"Start":"00:07.230 ","End":"00:09.930","Text":"Here, we\u0027re talking about an electrical synapse,"},{"Start":"00:09.930 ","End":"00:11.505","Text":"not a chemical 1."},{"Start":"00:11.505 ","End":"00:14.355","Text":"Would they be synaptic vesicles?"},{"Start":"00:14.355 ","End":"00:16.680","Text":"Would they be voltage-gated ion channels?"},{"Start":"00:16.680 ","End":"00:22.455","Text":"Will they be gap junction protein or would they be sodium potassium exchange pumps?"},{"Start":"00:22.455 ","End":"00:23.940","Text":"Think of all of these."},{"Start":"00:23.940 ","End":"00:27.030","Text":"Synaptic vesicles contain chemicals."},{"Start":"00:27.030 ","End":"00:31.410","Text":"Voltage-gated ion channels are chemicals,"},{"Start":"00:31.410 ","End":"00:35.880","Text":"and sodium potassium exchange pumps are also involved chemicals."},{"Start":"00:35.880 ","End":"00:41.100","Text":"The only 1 that does not involve the chemicals would be gap junction protein."},{"Start":"00:41.100 ","End":"00:42.950","Text":"Let\u0027s see if that\u0027s the answer."},{"Start":"00:42.950 ","End":"00:45.305","Text":"If you recall this picture,"},{"Start":"00:45.305 ","End":"00:49.700","Text":"then you will remember that there are these proteins"},{"Start":"00:49.700 ","End":"00:55.295","Text":"in electrical synapses that can go between 2 different cells,"},{"Start":"00:55.295 ","End":"01:02.585","Text":"allowing things to move between the 2 different cells without a chemical synapse."},{"Start":"01:02.585 ","End":"01:07.909","Text":"Those are going to be called the channel"},{"Start":"01:07.909 ","End":"01:14.700","Text":"proteins or channel pores that are the gap junction proteins."}],"ID":29024},{"Watched":false,"Name":"Exercise 8","Duration":"31s","ChapterTopicVideoID":27836,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.930","Text":"The blank lobe, or which lobe of the brain contains the visual cortex."},{"Start":"00:06.930 ","End":"00:08.940","Text":"This is something we just have to remember."},{"Start":"00:08.940 ","End":"00:11.160","Text":"Remember there are 4 different lobes,"},{"Start":"00:11.160 ","End":"00:14.955","Text":"frontal, parietal, temporal, and occipital."},{"Start":"00:14.955 ","End":"00:18.030","Text":"This figure shows the various functions of"},{"Start":"00:18.030 ","End":"00:23.070","Text":"the various lobes and we were asked about the visual cortex."},{"Start":"00:23.070 ","End":"00:27.645","Text":"The visual reception is in the occipital lobe,"},{"Start":"00:27.645 ","End":"00:29.265","Text":"as you can see here."},{"Start":"00:29.265 ","End":"00:31.870","Text":"So that\u0027s our answer."}],"ID":29025},{"Watched":false,"Name":"Exercise 7","Duration":"1m 8s","ChapterTopicVideoID":27852,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.485","Text":"Which of the following molecules is not"},{"Start":"00:04.485 ","End":"00:10.500","Text":"involved in the maintenance of the resting membrane potential?"},{"Start":"00:10.500 ","End":"00:14.025","Text":"Would it be potassium cations, sodium,"},{"Start":"00:14.025 ","End":"00:18.540","Text":"voltage-gated ion channels, or calcium cations?"},{"Start":"00:18.540 ","End":"00:22.545","Text":"If you remember this figure,"},{"Start":"00:22.545 ","End":"00:28.935","Text":"then you\u0027ll remember that when in action potential is caused by"},{"Start":"00:28.935 ","End":"00:35.725","Text":"the sodium ions that go through the sodium ion channel,"},{"Start":"00:35.725 ","End":"00:39.770","Text":"and then potassium is what causes it afterwards to"},{"Start":"00:39.770 ","End":"00:44.725","Text":"rest and it goes through these voltage-gated ion channels."},{"Start":"00:44.725 ","End":"00:48.175","Text":"Yes. Those then potassium goes through,"},{"Start":"00:48.175 ","End":"00:53.585","Text":"that maintains the resting membrane potential or restores the resting membrane potential."},{"Start":"00:53.585 ","End":"00:58.500","Text":"The only thing not involved in this is calcium."},{"Start":"00:58.500 ","End":"01:02.930","Text":"Calcium cations are going to be our answer because"},{"Start":"01:02.930 ","End":"01:08.130","Text":"they are not involved in the maintenance of the resting potential."}],"ID":29026},{"Watched":false,"Name":"Exercise 9","Duration":"45s","ChapterTopicVideoID":27837,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.770","Text":"The what or what connects the 2 cerebral hemispheres?"},{"Start":"00:04.770 ","End":"00:07.049","Text":"Is it the limbic system,"},{"Start":"00:07.049 ","End":"00:09.285","Text":"the corpus callosum,"},{"Start":"00:09.285 ","End":"00:12.330","Text":"the cerebellum, or the pituitary?"},{"Start":"00:12.330 ","End":"00:17.025","Text":"You may remember that the brain has 2 hemispheres."},{"Start":"00:17.025 ","End":"00:21.255","Text":"Yes, there is the right hemisphere and the left hemisphere."},{"Start":"00:21.255 ","End":"00:28.040","Text":"They are connected between them by the corpus callosum,"},{"Start":"00:28.040 ","End":"00:29.935","Text":"as you can see here."},{"Start":"00:29.935 ","End":"00:31.730","Text":"It\u0027s not limbic system,"},{"Start":"00:31.730 ","End":"00:34.160","Text":"it\u0027s not going to be the cerebellum,"},{"Start":"00:34.160 ","End":"00:37.265","Text":"and it\u0027s not going to be the pituitary."},{"Start":"00:37.265 ","End":"00:40.610","Text":"Of course, it is the corpus callosum,"},{"Start":"00:40.610 ","End":"00:45.570","Text":"is the answer which connects the 2 sides of the brain."}],"ID":29027},{"Watched":false,"Name":"Exercise 10","Duration":"1m 5s","ChapterTopicVideoID":27838,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.055","Text":"Neurons in what control motor reflexes."},{"Start":"00:05.055 ","End":"00:07.185","Text":"Are they the neurons in the thalamus,"},{"Start":"00:07.185 ","End":"00:08.565","Text":"in the spinal cord,"},{"Start":"00:08.565 ","End":"00:11.820","Text":"in the parietal lobe or the hippocampus?"},{"Start":"00:11.820 ","End":"00:15.810","Text":"These are things that control motor reflexes."},{"Start":"00:15.810 ","End":"00:22.950","Text":"The motor reflexes are controlled without going to the brain."},{"Start":"00:22.950 ","End":"00:26.070","Text":"It\u0027s certainly not the thalamus and it\u0027s not going to"},{"Start":"00:26.070 ","End":"00:28.905","Text":"be anything else which is in the brain,"},{"Start":"00:28.905 ","End":"00:30.585","Text":"it\u0027s going to be in"},{"Start":"00:30.585 ","End":"00:36.905","Text":"the spinal cord because we\u0027re going to have reflexes that don\u0027t even involve the brain."},{"Start":"00:36.905 ","End":"00:43.669","Text":"Remember, you have these sensory neurons which then send a signal directly"},{"Start":"00:43.669 ","End":"00:46.550","Text":"to the spinal cord and the spinal cord then sends back"},{"Start":"00:46.550 ","End":"00:50.585","Text":"messages through these afferent neurons."},{"Start":"00:50.585 ","End":"00:55.235","Text":"Yes, the axiom of the afferent neuron directly to the muscle to remove,"},{"Start":"00:55.235 ","End":"00:59.855","Text":"let\u0027s say, your hand if it feels a very hot sensation."},{"Start":"00:59.855 ","End":"01:05.830","Text":"Our answer therefore is going to be the spinal cord."}],"ID":29028},{"Watched":false,"Name":"Exercise 11","Duration":"1m 23s","ChapterTopicVideoID":27839,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.595","Text":"This is an interesting question."},{"Start":"00:02.595 ","End":"00:07.515","Text":"It\u0027s based upon a real true story in which Phineas Gage,"},{"Start":"00:07.515 ","End":"00:10.575","Text":"who was a 19th century railroad worker,"},{"Start":"00:10.575 ","End":"00:15.030","Text":"he survived an accident that drove a large iron rod through his head."},{"Start":"00:15.030 ","End":"00:17.130","Text":"Well, you\u0027d expect that to kill him, wouldn\u0027t you?"},{"Start":"00:17.130 ","End":"00:25.025","Text":"But the injury resulted in becoming temperamental and capricious, but he didn\u0027t die."},{"Start":"00:25.025 ","End":"00:27.725","Text":"What part of the brain was damaged?"},{"Start":"00:27.725 ","End":"00:29.060","Text":"Was it the frontal lobe,"},{"Start":"00:29.060 ","End":"00:31.850","Text":"the hippocampus, the parietal lobe,"},{"Start":"00:31.850 ","End":"00:33.935","Text":"or the temporal lobe?"},{"Start":"00:33.935 ","End":"00:38.105","Text":"In the diagram in which we discussed the various lobes,"},{"Start":"00:38.105 ","End":"00:43.280","Text":"you\u0027ll remember that the frontal lobe included voluntary movement,"},{"Start":"00:43.280 ","End":"00:48.050","Text":"planning, intellect, problem solving, abstract reasoning."},{"Start":"00:48.050 ","End":"00:53.355","Text":"Well, those things may be have to do with temperament."},{"Start":"00:53.355 ","End":"00:57.470","Text":"Possibly, it\u0027s certainly more than touch perception, moving control,"},{"Start":"00:57.470 ","End":"01:01.745","Text":"more than visual reception and perception, and things like that."},{"Start":"01:01.745 ","End":"01:06.570","Text":"It has nothing to do with long-term memory or speech comprehension."},{"Start":"01:06.570 ","End":"01:08.060","Text":"So most likely,"},{"Start":"01:08.060 ","End":"01:09.570","Text":"it would be the frontal lobe."},{"Start":"01:09.570 ","End":"01:13.070","Text":"In fact, that is the answer."},{"Start":"01:13.070 ","End":"01:14.615","Text":"It\u0027s the frontal lobe,"},{"Start":"01:14.615 ","End":"01:19.250","Text":"which we learned primarily involves cognitive functions,"},{"Start":"01:19.250 ","End":"01:21.130","Text":"such as planning, problem solving,"},{"Start":"01:21.130 ","End":"01:23.960","Text":"social skills, and decision making."}],"ID":29029},{"Watched":false,"Name":"Exercise 12","Duration":"1m 6s","ChapterTopicVideoID":27840,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:08.900","Text":"Activation of the sympathetic nervous system causes what?"},{"Start":"00:08.900 ","End":"00:10.965","Text":"Now, we\u0027re talking about activation."},{"Start":"00:10.965 ","End":"00:17.489","Text":"Remember, the sympathetic nervous system is the fright-flight response."},{"Start":"00:17.489 ","End":"00:25.230","Text":"That is going to cause which of the following: an increased blood flow to the skin,"},{"Start":"00:25.230 ","End":"00:28.410","Text":"a decreased heart rate or an increased heart rate?"},{"Start":"00:28.410 ","End":"00:34.207","Text":"It\u0027s probably one of these two since it can\u0027t be both and it does affect our heart rate."},{"Start":"00:34.207 ","End":"00:38.580","Text":"When we have fright-flight response,"},{"Start":"00:38.580 ","End":"00:40.175","Text":"our heart rate increases,"},{"Start":"00:40.175 ","End":"00:42.660","Text":"or would it be increased digestion."},{"Start":"00:42.660 ","End":"00:45.860","Text":"You remember this figure which has"},{"Start":"00:45.860 ","End":"00:51.695","Text":"all the different responses that occur in a sympathetic nervous system reaction,"},{"Start":"00:51.695 ","End":"00:55.725","Text":"and one of them is acceleration of the heartbeat."},{"Start":"00:55.725 ","End":"00:59.280","Text":"It\u0027s not increased blood flow to the skin,"},{"Start":"00:59.280 ","End":"01:00.930","Text":"it\u0027s not a decreased heart rate,"},{"Start":"01:00.930 ","End":"01:03.155","Text":"it\u0027s not increased digestion,"},{"Start":"01:03.155 ","End":"01:06.450","Text":"it is an increased heart rate."}],"ID":29030},{"Watched":false,"Name":"Exercise 13","Duration":"55s","ChapterTopicVideoID":27841,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.195","Text":"Where are parasympathetic preganglionic cell bodies located?"},{"Start":"00:06.195 ","End":"00:11.566","Text":"We\u0027re asking now where the preganglionic cell bodies are located."},{"Start":"00:11.566 ","End":"00:14.010","Text":"Are they in the cerebellum, the brainstem,"},{"Start":"00:14.010 ","End":"00:17.565","Text":"the dorsal root ganglia, or the skin?"},{"Start":"00:17.565 ","End":"00:26.520","Text":"For that, we turn back to a figure which showed the parasympathetic system."},{"Start":"00:26.520 ","End":"00:32.280","Text":"We see that the nerves primarily come from the brainstem,"},{"Start":"00:32.280 ","End":"00:35.693","Text":"not from places which are along the spinal cord,"},{"Start":"00:35.693 ","End":"00:38.100","Text":"but rather from the brainstem."},{"Start":"00:38.100 ","End":"00:45.195","Text":"The spinal cord was where we found the sympathetic neurons emanating from."},{"Start":"00:45.195 ","End":"00:48.760","Text":"Brainstem is going to be our answer."},{"Start":"00:48.760 ","End":"00:55.620","Text":"Therefore, we are going to cancel the others and mark brainstem as our correct answer."}],"ID":29031},{"Watched":false,"Name":"Exercise 14","Duration":"48s","ChapterTopicVideoID":27842,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.145","Text":"What is released by motor nerve endings into muscle."},{"Start":"00:05.145 ","End":"00:06.930","Text":"Or onto muscle, whichever."},{"Start":"00:06.930 ","End":"00:09.510","Text":"Any case, remember there are"},{"Start":"00:09.510 ","End":"00:16.170","Text":"different neurotransmitters: acetylcholine, norepinephrine, dopamine, serotonin."},{"Start":"00:16.170 ","End":"00:19.860","Text":"So which is released by motor nerve endings into the muscle?"},{"Start":"00:19.860 ","End":"00:25.770","Text":"For that, we need just to remember that the answer is acetylcholine,"},{"Start":"00:25.770 ","End":"00:32.445","Text":"is what\u0027s going to be the neurotransmitter that is released onto muscle fibers."},{"Start":"00:32.445 ","End":"00:38.205","Text":"Acetylcholine is the main neurotransmitter released at the synapses,"},{"Start":"00:38.205 ","End":"00:39.925","Text":"they\u0027re at the muscle."},{"Start":"00:39.925 ","End":"00:43.730","Text":"It\u0027s not norepinephrine, it\u0027s not dopamine,"},{"Start":"00:43.730 ","End":"00:47.610","Text":"it\u0027s not serotonin, it\u0027s acetylcholine."}],"ID":29032},{"Watched":false,"Name":"Exercise 15","Duration":"49s","ChapterTopicVideoID":27843,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:07.200","Text":"Parkinson\u0027s disease is caused by the degeneration of neurons that release which chemical?"},{"Start":"00:07.200 ","End":"00:11.685","Text":"Is it serotonin, dopamine, glutamate, norepinephrine?"},{"Start":"00:11.685 ","End":"00:17.130","Text":"So again, this is something that we just need to remember, and it\u0027s dopamine."},{"Start":"00:17.130 ","End":"00:20.820","Text":"So the loss of dopamine neurons."},{"Start":"00:20.820 ","End":"00:26.295","Text":"Yes, the loss of dopamine neurons in the midbrain that regulates movement,"},{"Start":"00:26.295 ","End":"00:29.790","Text":"it\u0027s that which causes the disease."},{"Start":"00:29.790 ","End":"00:34.800","Text":"What happens is that dopamine or L-DOPA,"},{"Start":"00:34.800 ","End":"00:37.440","Text":"which is similar to dopamine,"},{"Start":"00:37.440 ","End":"00:39.870","Text":"is given to Parkinson\u0027s patients."},{"Start":"00:39.870 ","End":"00:43.255","Text":"So that\u0027s an easy way to remember this answer."},{"Start":"00:43.255 ","End":"00:45.938","Text":"Our answer is not going to be serotonin,"},{"Start":"00:45.938 ","End":"00:47.435","Text":"it\u0027s not going to be glutamate,"},{"Start":"00:47.435 ","End":"00:50.370","Text":"it\u0027s going to be dopamine."}],"ID":29033},{"Watched":false,"Name":"Exercise 16","Duration":"53s","ChapterTopicVideoID":27844,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.885","Text":"Here\u0027s another question that we just need to know the answer to."},{"Start":"00:03.885 ","End":"00:08.580","Text":"Strokes are often caused by which of the following?"},{"Start":"00:08.580 ","End":"00:10.980","Text":"Is it neurodegeneration,"},{"Start":"00:10.980 ","End":"00:13.440","Text":"blood clots or burst blood vessels,"},{"Start":"00:13.440 ","End":"00:15.210","Text":"seizures, or viruses?"},{"Start":"00:15.210 ","End":"00:17.765","Text":"Well, actually, many of"},{"Start":"00:17.765 ","End":"00:23.480","Text":"the nervous system diseases are caused by neurodegeneration or cell death,"},{"Start":"00:23.480 ","End":"00:24.980","Text":"but in this case,"},{"Start":"00:24.980 ","End":"00:29.510","Text":"strokes are very sudden and they are caused by"},{"Start":"00:29.510 ","End":"00:34.955","Text":"blood clots that can occur in various parts of the body or maybe burst blood vessels,"},{"Start":"00:34.955 ","End":"00:38.630","Text":"in the case, clots then travel through the blood,"},{"Start":"00:38.630 ","End":"00:41.015","Text":"and if they lodge in the brain,"},{"Start":"00:41.015 ","End":"00:46.235","Text":"they can suddenly kill a piece of the brain because not enough oxygen arrives."},{"Start":"00:46.235 ","End":"00:53.520","Text":"Our answer is going to be blood clots or burst blood vessels."}],"ID":29034},{"Watched":false,"Name":"Exercise 17","Duration":"46s","ChapterTopicVideoID":27845,"CourseChapterTopicPlaylistID":275104,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.209","Text":"Why is it often difficult to identify the cause of many nervous system disorders?"},{"Start":"00:06.209 ","End":"00:09.360","Text":"Why would it be so difficult to identify the cause?"},{"Start":"00:09.360 ","End":"00:12.555","Text":"Is it because the genes associated with the diseases are not known?"},{"Start":"00:12.555 ","End":"00:15.780","Text":"Is it because there are no obvious defects in brain structure?"},{"Start":"00:15.780 ","End":"00:20.405","Text":"Is it because the onsets and display of symptoms varies between patients?"},{"Start":"00:20.405 ","End":"00:23.705","Text":"Well, the brain is very complicated."},{"Start":"00:23.705 ","End":"00:27.770","Text":"All of these really seem to be summary of"},{"Start":"00:27.770 ","End":"00:33.770","Text":"the reasons that make it difficult to identify the cause of nervous system disorders,"},{"Start":"00:33.770 ","End":"00:37.670","Text":"and in fact, that is the answer to our question."},{"Start":"00:37.670 ","End":"00:41.570","Text":"All of these are important in making it"},{"Start":"00:41.570 ","End":"00:46.860","Text":"difficult to identify the cause of nervous system disorders."}],"ID":29035}],"Thumbnail":null,"ID":275104}]

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