| 00:02 | This is lecture five of Neuroscience and continue our discussions on glial cells. |
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| 00:11 | we already talked about radial glial cells they serve as guides for neurons and |
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| 00:18 | involved in the migration and early guidance these cells and microglial cells. Wait |
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| 00:27 | second. Let's move back right Rad glial cells. So we also |
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| 00:34 | microglial cells, but we'll come back talk to them one more time. |
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| 00:38 | little bit later. What we have oligodendrocytes. We already mentioned them oligodendrocytes |
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| 00:46 | the CNS are responsible for myelination where oligodendrocyte, they have many processes and |
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| 00:53 | processes will run around and axons. each one of these processes form a |
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| 01:00 | myelin segment along the neuronal axons as to the peripheral nervous system where this |
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| 01:08 | is produced by swan cells and Schwan . A single s swan cell is |
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| 01:15 | for single segment of this mild. here it's one process of 10 liga |
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| 01:25 | can insulate many processes and many Whereas the one cell is responsible for |
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| 01:33 | one segment of one axon. And between these m and insulated pieces of |
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| 01:41 | are what revolve loads of ground those loads of ground deer will have |
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| 01:46 | expressions of voltage gated, sodium and channels. And that's how the action |
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| 01:52 | will get regenerated. Once they get at the axon initial segment near the |
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| 02:00 | , they will regenerate each note of VRE and travel all the way to |
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| 02:04 | exon terminal. This is what myelination like. This is myelinated optic nerve |
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| 02:14 | that have been cut and cross You can see that the range of |
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| 02:19 | and forming around there are pretty complex direct action or at least I think |
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| 02:26 | or seven, maybe even myelin basic that are important in guiding this whole |
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| 02:33 | of insulation. And there's a number them involved because some of them are |
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| 02:38 | in cell recognition, recognizing between the denroy and neuron that this is a |
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| 02:45 | match. Uh that is not an . So others will be responsible for |
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| 02:52 | the initial contact and sheets. Uh sheets of myelin other proteins will be |
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| 02:59 | how compact it and control the compaction that myelin all interacting and creating these |
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| 03:07 | of myelin for the installation of If there are dysfunctions in myelin, |
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| 03:16 | may end up having a demyelinating And we're gonna talk about two |
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| 03:22 | So we're adding two more. We talked about epilepsy and status epilepticus. |
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| 03:28 | talked about Alzheimer's disease. We talked fragile x syndrome. Excellent. And |
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| 03:40 | we're gonna talk about multiple sclerosis of merit tooth disease. The multiple sclerosis |
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| 03:46 | a demyelination in the CNS. So affects oligodendrocytes, right. It's multiple |
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| 03:55 | sides of lesion which is sclerosis, sides are multiple. So these lesions |
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| 04:03 | not form in one area of the . It doesn't uh it, it's |
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| 04:08 | , it's distributed and it's different in individuals. It's an autoimmune neurological |
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| 04:17 | Myelin, in this case is being by a person's own immune system And |
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| 04:26 | potentially also targeting myelin basic pronouns. it recognizes for one reason or |
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| 04:36 | its own produced pro dance and Mylin an invader. Uh it causes a |
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| 04:47 | of inflammation in the central nervous And you will see that inflammation is |
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| 04:52 | a common thread here that we see in the diseases like epilepsy, Alzheimer's |
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| 05:00 | , uh multiple sclerosis, it causes . And once axons lose the |
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| 05:09 | there's a complete loss of axons and of axons and loss of, of |
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| 05:16 | as well. There is a genetic that involves multiple genes that doesn't mean |
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| 05:25 | it's inherited. But the predisposition, not an inherited disease. The predisposition |
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| 05:33 | having a disease can be passed, causes uh besides this potential genetic |
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| 05:43 | then you have to have something else awakens this disease. And this disease |
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| 05:51 | has an onset at the age of to 30. So the onset age |
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| 05:56 | important here, onset age for you see, for example, |
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| 06:01 | It's really prevalent in very young It's also very prevalent in older |
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| 06:07 | Onset of Alzheimer's disease is typically 55 onset of multiple sclerosis. These are |
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| 06:15 | good exam questions uh at the age 20 to 30. Uh but what |
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| 06:21 | that other factor? What is that event that happens that awakens either the |
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| 06:29 | or if you don't have the what is the event that leads to |
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| 06:35 | and demyelination? It could be infectious like viruses. And and after the |
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| 06:42 | , after the infection has been the immune system still does not recognize |
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| 06:47 | infected axon. Now as its it still thinks that it still needs |
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| 06:51 | attack the axons. It doesn't stop attacks normal axons. It's one of |
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| 06:56 | theories, environmental factors. Vitamin D also implicated, it's more prevalent than |
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| 07:05 | . There's a lot of symptoms. when we talked about Alzheimer's disease, |
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| 07:09 | discussed some symptoms of Alzheimer's disease. lot of symptoms here of multiple |
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| 07:16 | blurred or double vision, muscle weakness painful muscle spasms. Why do you |
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| 07:24 | a person would have painful muscle The neurodegeneration is in the CNS, |
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| 07:33 | muscles. Let's say my hand arm muscles are controlled by my spinal |
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| 07:40 | , right? But the command is from where to control. We just |
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| 07:44 | that with neuralink, it's coming from motor cortex. So if your neurons |
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| 07:51 | missing insulation and different parts of the , including the parts of the brain |
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| 08:00 | control movement to certain extent or control of normal commands, then you can |
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| 08:08 | basically, it doesn't matter. You have myelin in the periphery, which |
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| 08:12 | s swan cells, but your commands from the central nervous system are |
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| 08:19 | So they don't get delivered properly for spinal cord to be executed. So |
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| 08:23 | somebody uh takes something and contracts their , now the command is coming from |
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| 08:29 | cortex, relax the fist, relax fist. And that information because of |
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| 08:35 | demyelination, axons are lost. There no communication between neurons or it's |
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| 08:42 | And it takes this command maybe 100 , relax the hand, relax the |
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| 08:47 | until it can be, you clenching like this could be very |
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| 08:53 | tingling, numbness because of the spasms the clenching or pain in the |
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| 08:58 | legs, trunk or face clumsiness. it affects, it affects almost the |
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| 09:04 | body. These effects in the periphery clumsiness. The effects of the pain |
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| 09:10 | arms and legs again is the fact the fact that your muscles get sore |
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| 09:15 | they're, when they work out, get sore. And if you don't |
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| 09:19 | relax on it, that can get too or you don't relax them in |
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| 09:23 | way that they need to be relaxed on the metabolism in the body, |
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| 09:29 | and physical fatigue, mood changes and could be cognitive dysfunctions also. So |
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| 09:35 | really kind of a varies across the because if demyelination happens in the frontal |
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| 09:41 | predominantly, then it may affect more the cognitive functions. If it happens |
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| 09:47 | the occipital lobe, it may affect of the vision or if it happens |
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| 09:52 | the tracks of the optic nerve. example, it can start affecting the |
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| 09:57 | and add it more blurry. So areas, motor closer to motor |
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| 10:03 | Um Treatments for this disease are pharmaceutical other treatments or other are uh physical |
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| 10:14 | . Um meditation, alternative treatments that out there apart from pharmaceuticals. And |
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| 10:21 | you want to read more information and should know that whatever you add a |
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| 10:28 | to, you should know that it's reliable source. It's not a popular |
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| 10:32 | to visit NN BS National Institute of Neurological Miso and stroke. The National |
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| 10:41 | of Health. Do you can type uh link these? You can click |
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| 10:46 | these link to read all of the that is kind of a synthesized here |
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| 10:52 | you. But it's always good to looking outside, especially for undergraduate students |
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| 10:57 | this stage, looking outside and to links and resources that are reliable, |
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| 11:03 | are peer reviewed of med that are by professional uh institutes uh like NIH |
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| 11:12 | NIN BS and also professional associations. lot of times, especially for rare |
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| 11:19 | . Uh before they get enough attention the bigger organizations, the myelinating disease |
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| 11:26 | the PNS is Shaco Merit disease that swan cells and in particular affects myelination |
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| 11:35 | the, and the limbs and legs arms. It's one of the most |
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| 11:40 | inherited neurological disorders. So, this inherited, you have demyelination. Uh |
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| 11:47 | onset age is typically in adolescence and adulthood. And in this case, |
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| 11:55 | actually uh a mutation that causes uh of myelin protein called P MP 22 |
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| 12:06 | we're not looking at and it's So there's too much of this |
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| 12:09 | you'll say, well, if it's much of some protein, then there's |
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| 12:12 | to be a lot of myelin. this is not, you know, |
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| 12:16 | things don't equate too much of one that out of seven may mean that |
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| 12:23 | other six are not operating properly. the increase or decrease does not necessarily |
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| 12:29 | to more or less uh myelin. this case, it's too much of |
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| 12:33 | protein and too little of the myelin of weakness or paralysis, high step |
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| 12:40 | with frequent tripping or falling balance Uh Individuals will have foot deformities, |
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| 12:48 | deformities and their legs are referred to inverted champagne bottle or just their knees |
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| 12:57 | buckled inside and they eat quite often pointing outwards. When the individuals that |
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| 13:04 | the, the CMT may also the will walk sideways rather than forward. |
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| 13:11 | their motion of walking is more swaying than moving forward. Uh It reduced |
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| 13:19 | to feel heat, cold and And you'll understand why when we study |
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| 13:24 | somatosensory system because it's the nerves, the installation. Therefore, the perception |
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| 13:30 | also reduced. It's not only the of demand, ok. Uh decreased |
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| 13:36 | of proprioception, proprioception is the ability know where your body, where your |
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| 13:43 | , where your joints are with respect the rest of the body parts, |
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| 13:47 | well as the earth of gravity as holds you to the earth. Uh |
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| 13:54 | with the spine such as scoliosis, displacement contractors, chronic shortening of muscles |
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| 14:01 | tendons around joins muscle cramping and nerve treatment. The treatment is really |
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| 14:08 | So for CMT the diagnosis as early possible is very important because then what |
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| 14:15 | is the deformities in the uh in bones come about because the muscles are |
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| 14:21 | contracting and relaxing properly because of the of the spinal nerves of the peripheral |
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| 14:30 | , those muscle contractions that are again for the arm to contract it's, |
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| 14:36 | instructing it, it's demanding it, not working properly. And because it's |
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| 14:41 | developmental disorder, it can reshape the . And so the early it is |
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| 14:47 | and the earlier these individuals are placed braces, the higher chance it is |
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| 14:53 | them to keep more of the uh and more of the proper anatomical shape |
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| 15:00 | their bones, which also helps with gait, the balance and walking and |
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| 15:06 | and so on physical therapy, of activity and then if they have |
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| 15:13 | you know, then everybody that has gets treated by different, different |
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| 15:21 | OK. So two major diseases you say there's a lot of symptoms |
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| 15:25 | Doctor Z, do I have to all of them? Um No, |
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| 15:31 | don't. But I think that if understand what the disease is, demyelination |
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| 15:39 | the CNS moans are not being that has an effect on the |
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| 15:45 | And there's pain and spasms and clenching the same happens here also because now |
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| 15:50 | have the myelination in the periphery. your CNS is functioning or lingo denroy |
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| 15:56 | fine. But in CMT Schwann cells degenerated and now the central commands are |
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| 16:04 | , you know, wave your right hand or squeeze it and relax, |
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| 16:09 | and relax. But the execution on peripheral side is failing is that |
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| 16:16 | So some of these things you should PNSCNS, age of onset, uh |
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| 16:24 | of the major symptomologies, but I not put, you know, match |
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| 16:28 | of these symptoms to one disease and to the other. And um it |
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| 16:33 | be my questions will be more OK, microglia, we already looked |
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| 16:40 | these really nice image. It's involved injury repair debris, clean up. |
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| 16:44 | are treated as macrophages almost at the . So they will engulf the dead |
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| 16:50 | and they will eat the dead cells then ostracized will come and eat the |
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| 16:56 | and then who is gonna eat the ? We don't know, maybe that's |
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| 17:03 | it ends actually. So far. the end of the story. It's |
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| 17:07 | developing story. So they, they uh inflammatory and immune response. They |
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| 17:14 | release cytokines and cytokine release is Cytokines will come up uh call upon |
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| 17:22 | immune response, call upon the immune to go into the brain and start |
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| 17:28 | the repair and recovery. They're sensing oxygen species. So R OS increases |
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| 17:37 | nitrous oxide uh and infections. They involved in extracellular signaling. And first |
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| 17:50 | all, they release cytokines and that's they communicate with other cells in the |
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| 17:55 | and the immune system. And then structure that you've seen here with their |
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| 18:01 | is extending out. Once they engulf dead cell, they become like a |
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| 18:06 | boy like structure actually. So they their structure. But despite all of |
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| 18:10 | , they're the most mobile units in brain that will actually move through the |
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| 18:14 | to execute their functions. Astrocytes uh very important in neuronal signaling and also |
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| 18:25 | blood brain barrier. So what is here is two neurons, you have |
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| 18:31 | presynaptic terminal again on the top here green round vesicles that are filled with |
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| 18:38 | transmitter. You have this yellow oyn spine and in blue, you have |
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| 18:46 | process that surrounds the presynaptic terminal and postsynaptic dendritic spine. And a lot |
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| 18:54 | times this kind of arrangement is referred as tripartite synapse. So, tripartite |
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| 19:03 | for three tripartite synapse where the first is neuron, one presynaptic. Second |
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| 19:12 | of this a synaptic neuron. And part is the astro side process. |
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| 19:18 | , what it does is it regulates content around the synapse. It |
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| 19:26 | In particular, if there are local and ionic concentrations in the brain |
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| 19:34 | such as potassium ostracizes will very quickly and slurp up these high concentrations of |
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| 19:45 | and spatially buffer through their own extensive uh processes. But also they will |
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| 19:55 | interconnected with other astro sites. And prevents from potassium having very high external |
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| 20:06 | , which can be detrimental to the that this is sustained instead be spatially |
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| 20:13 | and dilute in a way that rise the potassium concentration. Likewise, they're |
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| 20:20 | involved in neurotransmitter processing. They re neurotransmitters that get released from, from |
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| 20:29 | . And they also contribute to producing , which we already discussed as the |
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| 20:35 | neurotransmitter in the brain. So they not only the ions but they also |
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| 20:42 | the neurotransmitters and the concentrations of this and the amount that is available for |
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| 20:50 | to communicate with. So it's almost checking how many email messages to neurons |
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| 20:56 | set to send to each other by giving enough uh bandwidth or megabytes. |
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| 21:03 | , synapse formation of synaptogenesis because it's intricately involved. Both actually microglial cells |
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| 21:10 | ostracizes are involved in synaptogenesis, synaptic . The ability as we talked about |
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| 21:17 | the ability of the synopsis to become , larger more efficacious or smaller, |
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| 21:24 | , potentially be even driven away. synopsis can be formed at synaptic |
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| 21:30 | We control neuro growth and retraction and most abundant W cell. And in |
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| 21:38 | to that, their feet are positioned control blood brain barrier. So with |
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| 21:46 | that are in the blood, you in the beauty of cells that form |
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| 21:50 | walls of the blood vessels. So have the T junctions in between |
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| 21:55 | And the things that are not meant cross, they do not cross from |
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| 21:58 | blood into the brain. They only if they have transporters or cot |
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| 22:04 | if they're super small or if they're fat soluble or lipophilic because then they |
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| 22:10 | cross through plasma membranes of the Otherwise everything, it really gets really |
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| 22:16 | by the tight junctions which are further by parasites and then by ostracized. |
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| 22:24 | ostroy and feet is the police check from the brain side looking to see |
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| 22:31 | things can pass into the brain from blood. So you have this blood |
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| 22:37 | barrier. It's a great thing because separates what is in the blood and |
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| 22:42 | process into the brain. When we're . We're young, we have tight |
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| 22:50 | that were uh very tightly closed and older you get or if there is |
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| 22:55 | infection and inflammation, those tight junctions become loose. So blood brain barrier |
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| 23:01 | become loose again, it serves a protective function at the same time it |
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| 23:07 | certain difficulties for neuro pharmacological drug How, uh, how many of |
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| 23:16 | have thought how drugs get into the and how drugs are usually taken? |
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| 23:20 | , neurological drugs, let's say anti medications. Yes. Oh, |
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| 23:30 | I thought you had a question. . Well, how do, how |
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| 23:34 | you take medications? How do not ? But how do patients take |
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| 23:42 | They swallow a tablet fill? What happens to that table? |
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| 23:49 | Yeah. Where in the gut? yeah, it, it goes, |
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| 23:56 | drops into the first of all into esophagus, it goes into your |
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| 24:04 | Uh your gastric juices. There are ph 3.4 or something like that. |
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| 24:12 | how, how does it get into blood absorption through the digestive system? |
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| 24:29 | , digestive system? Yes. Very . Ok. Uh digestive system. |
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| 24:35 | . And what else happens with the system? A lot of stuff exits |
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| 24:39 | from the digestive system too. so when you take a medication, |
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| 24:48 | effective medication should dissolve very quickly. longer it goes into the digestive |
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| 24:54 | the longer it gets processed. There's chance that only a fraction, let's |
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| 24:59 | you took something 200 mg, there's a fraction of it that will get |
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| 25:04 | the blood out of those 200 Maybe it's gonna be just 2 mg |
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| 25:09 | , get out. The rest of gets processed by digestive system, it |
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| 25:14 | metabolized. There is liver metabolism that also. Uh now you have 2 |
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| 25:23 | in the blood. Now you have make sure there's 2 mg in the |
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| 25:28 | cross into the brain. So you to make sure that that molecule is |
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| 25:34 | is very small. Maybe it can some transporter to facilitate its entry into |
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| 25:41 | , into the brain. But that's to think about when you take 200 |
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| 25:47 | of Advil. Uh it would be . I'd be curious to know how |
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| 25:51 | of that actually gets into the If you have a headache, for |
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| 25:56 | , or since the headache is not in the brain, it's in the |
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| 26:02 | meninges and surrounding tissues, the So again, that's not a very |
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| 26:06 | indicator. Uh because the brain feels pain, it's the tissue surrounding |
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| 26:12 | the brain cells and neurons have no receptors. So there's the tissue surrounding |
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| 26:17 | , the meninges that have this So it's something interesting to think |
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| 26:22 | And uh neuro pharmacological drug designers always about these things, how to deliver |
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| 26:29 | most effectively. What if you had nasal spray? And instead of going |
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| 26:33 | digestive system, it goes directly into brain. What if you had a |
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| 26:38 | preparation and you rub something on your and it goes directly into the |
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| 26:42 | So it bypasses these routes, can the digestive system, sometimes can bypass |
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| 26:49 | . Um uh unlike the oral All right. So this concludes our |
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| 26:57 | on glia and neurons and uh nobody any questions. I'm gonna move on |
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| 27:06 | the next lecture. I think I how to fool this system. I |
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| 27:29 | have to disconnect from it. When gets, when it gets it, |
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| 27:33 | gets frozen, it gets frozen. now we're gonna move into, |
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| 28:05 | it really has a mind of its . Let me pause this recording for |
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| 28:11 | second and we're talking about neuronal membrane the membrane potential. What we call |
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| 28:21 | potential is voltage across the neuronal membrane any moment in time. And so |
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| 28:27 | we talk about resting membrane potential, as R MP, you will find |
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| 28:34 | most of the textbooks say that it minus seven to millivolts. And then |
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| 28:40 | other textbooks will say minus 6560 minus millivolts. It varies but it's somewhere |
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| 28:48 | minus seven to millivolts. That's, where the resting me potential is. |
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| 28:52 | varies across different all subtypes. So not just because it's wrong actually, |
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| 28:58 | somewhere around minus 70 in this diagram 65 millimoles ring me in the |
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| 29:06 | But at any given time in this resting membrane potential. This is |
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| 29:16 | mill measure here on this axis and is minus 65 mills. This resting |
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| 29:25 | potential is going to fluctuate minus 45 is another important value. This is |
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| 29:35 | threshold for action potential. So if one given moment, this ring number |
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| 29:42 | potential might be 65 negative might be might be 67 might be 60. |
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| 29:50 | constantly fluctuates based on the spontaneous inputs are coming into the cell. And |
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| 29:57 | some of the thermodynamic changes that are locally in the different patches of the |
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| 30:03 | . So if the cell moves this , this is called depolarization, the |
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| 30:11 | depolarizes. And if the cell membrane happens to reach this threshold value, |
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| 30:21 | will produce an action potential. So is going to be the discussion for |
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| 30:27 | next few lectures is how this rusting potential comes about and how neurons is |
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| 30:35 | membranes produce these action potentials. And on when the h of Oxley were |
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| 30:43 | these recordings, they would place an side of the cell and the volt |
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| 30:49 | or negative potential, negative 65 millivolts compared to the outside of the |
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| 30:55 | which was presumed neutral in charge or millivolts. So uh now what we |
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| 31:15 | to understand is the reason why we these fast potentials action potentials, which |
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| 31:21 | already mentioned in the previous lecture. about one to let's say three |
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| 31:28 | neuronal action potentials. So very short because we have to react to the |
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| 31:36 | world and we have to react in very fast manner. So we have |
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| 31:41 | have fast electrical events and fast synaptic . And so neurons are, in |
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| 31:48 | the fastest cells that you have in body for processing sensor information. And |
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| 31:54 | general for their activity that they can , some neurons are capable of firing |
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| 32:01 | spikes per second or producing activity at Hertz, which is a lot of |
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| 32:09 | potential. And one of the reasons action potentials need to be passed and |
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| 32:16 | cas and action potentials need to be passed. And the uh neuromuscular ajus |
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| 32:24 | is because we have to react to stimuli, We have to withdraw ouro |
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| 32:30 | stimuli. This is an example of person stepping onto a nail and immediately |
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| 32:37 | the leg without thinking and that happens a fraction of a second villain. |
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| 32:43 | so there's a circuit, this basic and will keep coming and uh revisiting |
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| 32:49 | certain extent the circuit. When we about neural transmission, we're gonna talk |
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| 32:53 | neuromuscular junction. But this circuit we started discussing that you have the sensory |
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| 33:00 | , which is, which is the gangland component. You have the motor |
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| 33:05 | which comes out of the ventral side the spinal cord. This is the |
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| 33:08 | nerve that is going to innervate this that is going to give the command |
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| 33:13 | this muscle to contract. So this here and this particular uh event of |
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| 33:23 | of the patellar tendon when you have stimulation of patella tendon here, sometimes |
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| 33:30 | doctor's office during regular checkup or neurologist's , they may put a little mallet |
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| 33:37 | your knee and they'll see how your leg bounces up, it's uh |
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| 33:43 | knee jerk stretch or patella tendon also reflex. So it actually involves |
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| 33:53 | these two cells. So first of the opt out of stimulus, that |
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| 33:58 | is gonna be a little valid in stimulant tendon that's going to get picked |
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| 34:04 | by the sensory. So, somatosensory , central axon of the pseudo unipolar |
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| 34:13 | root ganglion cell that releases glutamate onto motor neurons and excites motor neurons which |
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| 34:22 | multipolar cells and the exit out of ventral side and they release acetylcholine onto |
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| 34:30 | muscles to cause muscular contraction. I started a table for you last |
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| 34:35 | for different cell subtypes. So if have that table digitally on the |
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| 34:41 | that's a, that's a good information keep adding a listed there. The |
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| 34:46 | of the cells you should know for reg ganglion cell, motor neuron parameter |
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| 34:52 | . You should know um whether they excitatory inhibitory what neurotransmitter they release whether |
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| 35:00 | are projection cells or inhibitory interneurons. in this particular case, the sensory |
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| 35:09 | is gonna send the signal to this neuron. It's going to excite this |
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| 35:13 | neuron, this motor neuron is going excite this muscle. There's only one |
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| 35:19 | exci synapses between motor neuron and muscle this muscle is going to contract as |
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| 35:25 | muscle contracts, extensor, muscle contracts the quadriceps, extensor extends the |
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| 35:33 | Ok? Kicks it up. we all know that there is this |
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| 35:40 | quadriceps and the hamstring is an opposing . And we all know that if |
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| 35:46 | want to, for example, contract , you can feel it. What |
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| 35:50 | to your triceps, your triceps in back is relaxed. If you want |
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| 35:56 | contract your triceps, what happens to biceps? Your biceps is relaxed and |
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| 36:02 | . OK. So in order for circuit to fully function and just one |
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| 36:10 | , one monosynaptic connection is enough to a contraction or send the command for |
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| 36:16 | contraction of the muscle. But in for this to be effective extension, |
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| 36:21 | have to now excite inhibitory anti neurons live in the spinal cord. And |
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| 36:30 | the spinal cord, these inhibitory interneurons glycine, they also release Gava but |
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| 36:39 | mostly dominated by release of glycine. this is an inhibitory neurotransmitter. And |
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| 36:48 | this same axon that gets excited, sensory axon is going to excite the |
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| 36:55 | neuron. But for the reflex to affected, it's going to also excite |
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| 37:00 | inhibitor into neuron that inhibitor into neuron make sure that this motor neuron is |
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| 37:07 | in the silent. Therefore, there's contraction. Therefore, there is relaxation |
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| 37:11 | the opposing hamstring flexor muscle and you an effective reflex and the kick up |
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| 37:18 | the leg. What happens if you , for example, uh having a |
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| 37:27 | and there's no reaction, you bring a big m no. But |
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| 37:35 | means that there's something potentially wrong in circuit and doctors or neurologists can start |
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| 37:42 | certain things. There may be not sensitivity in the sensory also root |
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| 37:48 | There might be too much uh uh I inhibition, for example, that |
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| 37:54 | not functioning. So the opposing muscle not relaxing and the doctor can feel |
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| 38:00 | the opposing muscle is not relaxing. you can start deducing some very basic |
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| 38:05 | about the serpent. And of then send a patient uh follow up |
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| 38:10 | if they do indeed have problems with , with this uh patella tendon |
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| 38:16 | OK. So monosynaptic is enough to contract the muscles and you have to |
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| 38:25 | more than one synapse. So poly is to have an effective kickup |
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| 38:33 | And this is a simple reflex. a lot of uh complex reflexes that |
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| 38:38 | mediated by many synopsis and many uh in in the brain or or brain |
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| 38:45 | uh such as a gag reflex, example. OK. So into neurons |
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| 38:51 | the spinal cord. Wow, pretty . So there is not only that |
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| 38:58 | release uh glycine and Gaba, but that there are different types of the |
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| 39:05 | with different dialects, tonic firing, bursting, b, light, firing |
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| 39:10 | spiking or electron firing. So they different dialects, the neurons in the |
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| 39:18 | cord. And they have distinct And obviously another thing that we talked |
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| 39:24 | . Last lecture is their morphology that's in subtyping neurons, their dialects or |
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| 39:31 | firing patterns are important and their cells markers or molecular profiles is what's going |
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| 39:39 | determine what subtype of a neuron. this case, inter neuron in the |
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| 39:45 | cord is being present or being recorded or studied my neuro cells. |
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| 39:56 | I just did you a huge When did I start writing this last |
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| 40:03 | ? Like, so here you This is a great study guide. |
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| 40:07 | you notice that I wrote in the that you'll have 40 questions. Uh |
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| 40:13 | they're worth about 100 points. So all of my questions are weighted the |
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| 40:18 | . They're not all two points per . Uh This typically matching question is |
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| 40:27 | C subtypes that I may ask you their functions, location or neurotransmitters. |
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| 40:34 | so this question may be worth five . For example, other questions like |
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| 40:38 | and false may be worth a point a half. Uh other questions, |
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| 40:43 | choice might be worth two points, points depending on the complexity or how |
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| 40:48 | information is. Is there a question matching? For example, you |
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| 40:53 | what does it mean by pre um like to uh side to? |
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| 41:00 | I mean, we talked about this lecture that you have cells that are |
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| 41:05 | to project out of the network uh parameter cells. And you have interneurons |
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| 41:10 | are local interneurons. And you also that right here, you see the |
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| 41:20 | and the neuron, it stays with spinal cord, the motor neuron that |
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| 41:24 | actually projection cell that grows into into the muscles. And that can |
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| 41:29 | uh this is just in the spinal , but this could be between two |
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| 41:34 | networks between network A and B. gonna be cells that are projection cells |
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| 41:40 | then C D in Athens, local will stay locally here. And we |
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| 41:49 | talked about how there's a greater variety these interneurons. And also we're seeing |
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| 41:55 | not only in the hippocampus, we're seeing a great variety of morphological distinct |
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| 42:01 | and functional, distinct subtypes in the cord and the interneurons. So that |
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| 42:07 | , you know, not that much in the motor neurons, but more |
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| 42:11 | in the inhibitor interneurons that essentially control , how much of that information is |
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| 42:18 | between networks or how much of the muscles in the case of the reflexes |
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| 42:24 | inhibited or in what pattern it may inhibited. So, yes, please |
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| 42:31 | this. Uh And uh you'll be . The cast of chemicals. |
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| 42:43 | OK. No, I started you finish it. So it's |
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| 42:51 | it's a powerpoint. So you can uh you know, insert more uh |
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| 42:57 | uh as we study more information. , the cast of chemicals that creates |
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| 43:04 | potential across number. And then we about this resting memory potential minus 65 |
|
| 43:11 | , we have ions, we have that surrounds or these ions are dissolved |
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| 43:16 | water, it's uh polar. So both inside the so and extracellular fluid |
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| 43:22 | it's oxygen that attracts extra electrons and negative charge. Hydrogen has positive |
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| 43:29 | You have h2o other polar molecules dissolve water. Very basic stuff. Ions |
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| 43:36 | atoms of molecules that have a net charge. They form ionic bonds such |
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| 43:42 | sodium fluoride salt difference in the number protons or electrons is what we call |
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| 43:49 | valence or charge. So you can N A plus which is monovalent versus |
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| 43:56 | two plus, which is divalent CS positive charge and A plus versus anions |
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| 44:04 | negative charge like chloride minus, for . And that's just a little type |
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| 44:11 | the. So some basic stuff for . So uh sodium chloride here, |
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| 44:18 | example, is dissolved in water and dominating in that extracellular fluid. Um |
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| 44:26 | is just the repetition, CS and . The CS and anions will be |
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| 44:32 | by water molecules. And we refer these spheres of hydration or sometimes cloud |
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| 44:38 | hydration because depending on the size and charge, the spheres of hydration will |
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| 44:45 | have a different size, depending on size and the charge of the ions |
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| 44:51 | bilayer in the membrane. We already about the hydrophobic versus hydrophilic components. |
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| 45:00 | hydrophilic is dissolved in water due to electrical charge. Uh but these stay |
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| 45:08 | , they don't dissolve. So, are hydrophobic and they contribute to rusting |
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| 45:12 | action potentials. So you have this . This membrane is what separates the |
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| 45:19 | and ions cannot cross through this phospholipid . They need channels in order to |
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| 45:27 | the plasma membrane, they cannot they cannot squeeze themselves in between the |
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| 45:34 | hydrophilic and hydrophobic compounds there. Uh we have amino assets which are the |
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| 45:43 | blocks for proteins and building blocks for of interest for us which are channels |
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| 45:49 | in this case, ion channels. for the next three lectures, we |
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| 45:53 | talk about voltage gated or voltage dependent channels, especially when we get to |
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| 45:59 | action potentials. Next lecture. But acids are you building blocks, they |
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| 46:06 | peptide bonds in between them. You essential and non essential amino acids. |
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| 46:13 | amino acids are the ones that you to ingest. So they do |
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| 46:18 | you do not synthesize them. They from your food dietary intake. Quinoa |
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| 46:25 | one of the best grains that has of the most diverse composition of the |
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| 46:32 | amino acids um which is really cool if you don't use quinoa and in |
|
| 46:39 | diet, I don't use enough of , but I just used it the |
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| 46:42 | day. So I talk about Uh it's a pretty cool grain, |
|
| 46:47 | know, because sometimes when you're cooking or especially if you're preparing food |
|
| 46:54 | Uh It's difficult to think of like is gonna be my carb, what |
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| 46:58 | gonna be my protein? What is be my veggie you know. Uh |
|
| 47:04 | and when you start thinking about it's like rice, pasta, uh |
|
| 47:10 | , rice, pasta, potatoes, , fries, pasta. No, |
|
| 47:18 | you know, so it's important to all of these different grains like you |
|
| 47:22 | , on your diet. So these acids, they serve as building blocks |
|
| 47:28 | proteins. They have these primary structures become secondary structures and as they wind |
|
| 47:36 | into that al he don't exist or in the south and native sheets as |
|
| 47:42 | secondary ter structures, the co sun . So the secondary structures is a |
|
| 47:52 | . These transmembrane segments come together and ordinary structure, uh tertiary structure of |
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| 48:00 | subunit. These subunits come together and form the whole channel and the composition |
|
| 48:07 | these channels could be from several different of sub units. So they will |
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| 48:13 | different designations such as alpha beta gamma some other protein channels like NR one |
|
| 48:20 | two. So you have proteins, have polar R groups, nonpolar R |
|
| 48:28 | . These proteins are selected for they're selected for specific ions. That |
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| 48:34 | that an ion channel selected for sodium going to conduct sodium. A channel |
|
| 48:41 | for potassium is going to allow for to flux through it. Calcium is |
|
| 48:47 | to allow for calcium to flux through lot of these channels are voltage gated |
|
| 48:52 | we'll talk about. When we talk neurotransmission, we'll talk about Ln gated |
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| 48:57 | channels, talk about auditory system and we'll talk about mechanically gated uh hair |
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| 49:04 | or mechanically gated potassium channel. So is gonna be more information coming your |
|
| 49:10 | . So, thank you very much your patience and I hope everyone has |
|
| 49:14 | good weekend. Uh, the rest the week, you know, I'll |
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| 49:17 | everyone here on Monday. |
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