| 00:04 | Yeah. All right. Good morning today. I know that fun |
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| 00:10 | We're going to be dealing with electrical . Alright. That's that's kind of |
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| 00:15 | great George, what the class is to be about today, looking at |
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| 00:18 | potential and action potentials how they're formed what they do and then what we're |
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| 00:23 | is we're going to transition from that talk about how the synapse works. |
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| 00:28 | . And so we're going to look what is the synapse? What's his |
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| 00:31 | ? And how does it go about its job? So, that's kind |
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| 00:34 | like the big picture. And then should get us up through all the |
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| 00:37 | We need to know for the first the second example. Hey, thank |
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| 00:44 | . Yeah, but before we do that we need to do a vocabulary |
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| 00:47 | . All right. And it's gonna like we really have to do this |
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| 00:51 | . It is important because the terminology be a little bit confusing. |
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| 00:56 | what we have here is we got , polarized, hyper polarized and re |
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| 01:00 | . Alright. And so what I to do is I want you to |
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| 01:03 | back to third grade. Remember third people like no one person's? |
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| 01:08 | They want to know. All So do you remember the number |
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| 01:12 | All right. So now you can it's like you have the number line |
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| 01:14 | had negative on one side positive on other. I should flip that around |
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| 01:17 | this would be your negative. This be a positive. Right? And |
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| 01:20 | when we're on that number line we zero and then we're either moving away |
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| 01:24 | zero in either direction. All So when you're on zero on a |
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| 01:29 | line, you're what we call non . All right. Any time you |
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| 01:35 | off zero If it's .1 or a , it doesn't matter how big or |
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| 01:40 | small is you become polarized. All . And when we talked on |
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| 01:45 | we talked about how we were measuring cell and we put a probe inside |
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| 01:49 | cell and we put a ground on outside. And we're asking the |
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| 01:53 | what is the charge inside the All right. And so what we're |
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| 01:57 | doing is we're asking the question of is the polarity inside the cell? |
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| 02:02 | right. Because it's not zero. could be but it's not All |
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| 02:06 | So, whenever we're looking at a , we're gonna be looking at a |
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| 02:11 | of a cell that's already polarized. already been moved on that number line |
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| 02:15 | one direction or the other. Now that we typically look at are negatively |
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| 02:20 | on the inside. They are already a polarized state in the negative |
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| 02:25 | All right. So, the way here. Okay. Now the neuron |
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| 02:28 | -70. We talked a little bit why that is Okay, so, |
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| 02:32 | standing over here on -70 euros over . If I move toward zero, |
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| 02:39 | becoming less polarized. Right? -70 step closer would be -69. The |
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| 02:46 | step would be -68 and so on so on. I'm becoming less polarized |
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| 02:50 | I was before. That is called polarization. All right. If I |
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| 02:55 | turned back to my original polarized I'm re polarizing. Okay. And |
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| 03:02 | if I move further from zero, other words, zeros over there in |
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| 03:07 | direction. I'm becoming more polarized. hyper polarizing. All right now, |
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| 03:12 | do I bring all this stuff All right. Because these are the |
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| 03:16 | that we use when we talk about cell, when we're opening and closing |
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| 03:21 | and we're moving items back and All right. So cell becomes deep |
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| 03:26 | . It's becoming less polarized than it before. And activity is happening in |
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| 03:30 | cell. If we're coming becoming more , were becoming hyper polarized. And |
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| 03:34 | activity is happening in the cell. , So these states are going to |
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| 03:39 | or going to tell us how the is behaving under those particular conditions. |
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| 03:45 | . And so that's why the language important. Now, there are sometimes |
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| 03:50 | will see not this simple chart that looking at right here, but it |
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| 03:54 | be positive. And so if I'm here in the positive plane, if |
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| 03:57 | moving towards zero, I'm still d . Even though I'm moving in the |
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| 04:01 | direction. I was when I was the negative plane. Right? And |
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| 04:05 | same thing. If I move further from zero, I'm becoming hyper |
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| 04:09 | This is why the language becomes important you have to understand your frame of |
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| 04:13 | now because ourselves are already negatively Typically what we're going to see is |
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| 04:18 | when we see ions moving into a and we are deep polarizing those ions |
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| 04:24 | are moving into cells because remember we at those basic ions are primarily |
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| 04:28 | So when we see a net positive of set of ions into the cell |
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| 04:33 | say net flow of positive ions than deep polarizing. So, typically, |
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| 04:39 | what's going on now. Is it what's going on? Not always, |
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| 04:44 | 99.9% of the time. And the that you'll see in your classes today |
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| 04:48 | in the near future, that's what's on. Conversely, if you're hyper |
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| 04:53 | and what you're seeing is a net of positive ions out of the |
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| 04:57 | In other words, I'm taking positive away from the cell so the inside |
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| 05:00 | becoming more and more negative. Hence polarization. All right. So, |
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| 05:07 | our starting point today. A lot the stuff we're gonna be dealing with |
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| 05:10 | abstract. So, you're gonna have kind of just take that step back |
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| 05:12 | go, don't ask what is going in my body. It's going on |
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| 05:15 | over the place. All right. are abstract ideas that are a little |
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| 05:19 | deeper to help us understand what's going in the south. So, I |
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| 05:24 | I gotta press that. So, gonna be talking about two different types |
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| 05:29 | electrical potentials. We talked about the having a resting membrane potential. What's |
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| 05:34 | on when no ions are moving back forth. There's a there's leak channels |
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| 05:39 | there's pumps. And basically find a where the membrane the difference in charge |
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| 05:43 | that membrane comes comes to a certain at rest. All right. That's |
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| 05:49 | we were talking about on Tuesday. -70. All right. And so |
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| 05:54 | we have is we have cells that take advantage of that potential energy and |
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| 05:59 | opening and closing channels we can create movement of ions that then become electrical |
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| 06:05 | that the cells can then use. those two types of signals are two |
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| 06:09 | of potential changes that occur. Have . It's a greater potential or an |
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| 06:14 | potential. All right, great Or have different grades to them. |
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| 06:20 | right. They can be big or . They can be long or or |
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| 06:25 | duration. Hence the term graded We typically use these short term |
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| 06:31 | Short distant signals. So, you imagine a cell We didn't really talk |
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| 06:35 | how big neurons are, neurons can very, very, very tiny. |
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| 06:40 | they can be very, very, big. I want you to envision |
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| 06:43 | a moment. My little toe, though you can't see it. All |
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| 06:47 | . And I want you to imagine is a neuron that travels from my |
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| 06:50 | cord all the way down the length my leg, down to that little |
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| 06:53 | to make it wiggle. So that , that one cell is about this |
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| 07:00 | that's a big sale. Wouldn't you now it's itsy bitsy teeny tiny in |
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| 07:03 | of diameter. But in terms of it's very far. And so when |
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| 07:07 | talking short distance changes, we're talking very short distances on the length of |
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| 07:12 | cell. But when we talk about distance signals, we're talking along the |
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| 07:18 | of that cell. Okay, and where we're going to use an action |
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| 07:23 | . And they're very very different in of how they behave and what's going |
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| 07:27 | . And if you've taken upper level , you've already learned this stuff and |
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| 07:29 | you can probably fall asleep. But you've never seen this stuff before, |
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| 07:32 | can be kind of confusing. If you know, if you don't kind |
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| 07:37 | take that step back and say, , this is abstract. All right |
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| 07:41 | , where do we get these? that changes that membrane permeability? Remember |
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| 07:45 | horrible equation? I said you didn't to remember? Yeah, if you |
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| 07:48 | look at that equation, it's talked permeability. So anything that changes permeability |
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| 07:53 | change the movement of ions and anything alters the ion concentration on either side |
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| 07:59 | the membrane. So in other if I open up channels. I'm |
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| 08:02 | permeability which causes ions to move, means I'm changing concentrations. All |
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| 08:08 | So, really, basically, all gotta do is open and closed |
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| 08:11 | That's that's the nuts and bolts of is what it boils down to |
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| 08:14 | I'm opening and closing channels. This does not want to work for me |
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| 08:19 | . All right. Now many of slide to have are going to be |
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| 08:23 | picture like this and then a lot explanation on it. And then the |
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| 08:25 | slide will be a different picture with same explanation. Because I think the |
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| 08:29 | probably do a better job of explaining a whole bunch of the text |
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| 08:33 | All right. So, what we was a great potential as a short |
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| 08:36 | signal. It's basically a local change a local environment. Now, this |
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| 08:41 | not the greatest picture. But what have here is you can see here's |
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| 08:44 | cell. All right. There's the terminal that we describe and we have |
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| 08:49 | releasing some sort of message. This gonna be a chemical message. And |
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| 08:53 | it's gonna do is it's gonna bind a ligand gated channel. That channel |
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| 08:57 | up that allows the inflow or the of ions. In this particular |
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| 09:02 | we're seeing the inflow of sodium. so what's gonna happen is you can |
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| 09:07 | at the point of entry, there's and tons of sodium. Remember the |
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| 09:10 | I gave you all those couples on side or not. The couples, |
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| 09:14 | were couples yet, They wanted to couples there on either side of the |
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| 09:17 | . Right? And if you open that gate, you can imagine there's |
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| 09:21 | to be this rush of of ions that gate or Russia really in this |
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| 09:26 | people. Right. So that's what's . So at the point of entry |
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| 09:31 | where you're going to see the biggest , the biggest change is taking |
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| 09:36 | All right. And that's what this is trying to show you down here |
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| 09:39 | if you're measuring it right here at site of excitation, that's where the |
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| 09:44 | changes. Now. These are What are they looking for? If |
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| 09:49 | sodium on what are you looking The negative charge, it doesn't matter |
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| 09:53 | it is. As long as it's , they're not picky, they're only |
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| 09:57 | about the charge part. Right? what they do is they come in |
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| 10:00 | the first thing we're gonna do is a negative charge and they're gonna |
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| 10:03 | how you do it? And they're hook up. All right. So |
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| 10:06 | you take that charge that's matched up another charge, it can't be moving |
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| 10:12 | . What's happening is as you move and further and further away from the |
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| 10:18 | , there's gonna be less and less charges available. So you don't see |
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| 10:22 | in terms of the voltage. Remember tissues that change or the difference in |
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| 10:27 | . So the further away is the and lower gets in terms of the |
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| 10:33 | . Now, if you're saying, , this doesn't make a lot of |
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| 10:35 | to me. What's a better way explain this? All right. Have |
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| 10:39 | ever thrown a rock into a smooth or pool that has no ripples, |
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| 10:43 | in it. Right. So you the rock and you throw it in |
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| 10:45 | and you get that little splash, get the ripples going away at the |
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| 10:49 | of entry. You have the biggest as you move further and further |
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| 10:53 | That ripple gets smaller and smaller and . Now, the reason for that |
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| 10:58 | a little bit different. It has do with resistance in the water and |
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| 11:00 | like that. But can you visualize because that's what's kind of going on |
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| 11:05 | is basically can think about as I'm it up. So I'm putting a |
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| 11:08 | bunch of ions. But as I further and further away from the side |
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| 11:11 | excitation, the amount of islands available interact becomes less and less and |
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| 11:17 | Does that make more sense? so a graded potential is very |
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| 11:25 | It's local meaning it happens in a specific location, Right? And it |
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| 11:30 | have varying degrees of magnitude, meaning can have different heights, different |
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| 11:36 | All right. So, I used example here. I said, |
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| 11:38 | it can be a 10 million volt or can be a five minute bold |
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| 11:41 | to Millersville change. It could be than that can be all varying different |
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| 11:46 | in magnitude. And in this case looking at a deep polarization, but |
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| 11:51 | can also have a hyper polarization. just depends on what type of channel |
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| 11:55 | opening in which direction the islands are . Again. This happens to be |
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| 11:58 | deep polarization. Now, the most type of channels that are going to |
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| 12:03 | up. We're going to be sodium . And so if it's a sodium |
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| 12:06 | , that means sodium is going to into the cell because that's the direction |
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| 12:09 | tends to go. All right. so that's why you end up with |
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| 12:13 | deep polarization. Really, I'm not to have a lot of fun with |
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| 12:19 | . All right. So, what little slide is trying to show you |
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| 12:24 | with magnitude and duration. All So, great potentials can have varying |
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| 12:29 | and varying durations. It's dependent upon stimulus. I'm going to give you |
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| 12:32 | dumb example. Alright, This example not accurate, but it's something that |
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| 12:37 | can visualize. All right. If take a little tiny needle and I |
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| 12:40 | like this, you go book, , you're going to get a very |
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| 12:44 | quick response. Right? If it's and sure, it'd be like a |
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| 12:48 | very small. Not quite painful But if I do a little bit |
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| 12:53 | . Right, You're gonna you're gonna something harder. Would you agree with |
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| 12:57 | right now, when I poke you a needle. You're not producing a |
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| 13:00 | potential. That's why I say it's it's a terrible example. But you |
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| 13:04 | understand magnitude, right? A simple tiny poke and move away real quick |
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| 13:09 | going to be pretty soft response One is going to give you a |
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| 13:13 | response. Right, okay, now the needle, me taking that needle |
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| 13:17 | then digging it in and holding it for a while. Is that pain |
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| 13:21 | last for a while? Okay, now you've got two different aspects to |
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| 13:26 | ? You have magnitude. Right? much pain I'm I'm perceiving versus how |
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| 13:31 | I perceive the pain. So, potentials are going to be dependent upon |
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| 13:37 | durations of stimulation and how strong that is. And that's what this is |
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| 13:43 | to show. You. Look, is a small stimulation. Here's a |
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| 13:45 | stimulation. Here's a bigger stimulation. is what you that's showing you the |
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| 13:49 | down here. This is showing you response to the cell. Alright, |
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| 13:54 | deep polarization that's occurring in response to different stimuli. All right. One |
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| 14:00 | greater than the next so and so . What this is not showing |
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| 14:04 | These are each done with the equivalent of time. So, this particular |
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| 14:08 | is not showing you duration. you can imagine duration would be in |
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| 14:12 | direction because this is the time component here. Alright, so duration and |
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| 14:21 | of the stimulus have a direct effect this duration and the magnitude of the |
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| 14:29 | potentials response or the response that's produced the greater potential. Just gonna be |
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| 14:38 | right. I've already kind of mentioned . Greater potential are going to be |
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| 14:44 | lived. The intensity is going to short lived in the sense of it |
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| 14:49 | travels a very, very short distance from the side of stimulation and there's |
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| 14:54 | reasons why this is. But the part of the difference is that each |
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| 14:59 | is seeking out its opposite charge and once it finds its opposite charge, |
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| 15:04 | no longer having to seek for So, what you're looking at is |
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| 15:08 | as you move further and further away the point of stimulation is those are |
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| 15:13 | free ions that are still seeking out a partner. All right, so |
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| 15:19 | why we don't see it. great potentials are very, very short |
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| 15:22 | . They basically open and close the , the island's flow in during the |
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| 15:26 | of open and then they just kind die out over this very short |
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| 15:29 | And I think this picking Yeah, picture same slide. But it kind |
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| 15:33 | shows us a little bit better. right. I want to ignore the |
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| 15:37 | up here on the top, ignore one and the two up here or |
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| 15:40 | two and the three. Excuse Um Because it is true, greater |
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| 15:44 | don't have direction. It's like I , if you drop the rock into |
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| 15:47 | pond, the ripple goes in all . Right? So, great potentials |
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| 15:52 | not being directed in a particular They just go away from the side |
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| 15:55 | stimulation. Just like what we saw the previous picture where was going left |
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| 15:59 | right. That's what this is trying do. But I want you to |
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| 16:01 | in terms of moving towards the cell . All right. It is going |
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| 16:05 | opposite direction. But I didn't do any good. So, you can |
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| 16:08 | here here is the point of So look at the deep polarization. |
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| 16:12 | large that is. Again, we're looking at a value. It's just |
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| 16:15 | it big? It's big as you away from the side of stimulation, |
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| 16:21 | wave gets smaller and smaller and All right. Just like if you |
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| 16:28 | the rock in because you have a splash and the wave would slowly die |
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| 16:32 | over time. All right. And what's going on. It's dying out |
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| 16:39 | all those ions are finding their Now, there are two different types |
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| 16:46 | greater potentials and neurons that we need be aware of. Here's the good |
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| 16:52 | . This is easy. Bad Lots of abbreviations. So when you |
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| 16:56 | in abbreviations, it's the alphabet soup causes it to get confused and throw |
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| 17:00 | hands up and say I'm done, going to law school. All |
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| 17:03 | So don't be scared of the Alright. The first type. Here's |
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| 17:09 | long name excitatory post synaptic potential. ? We name things for what they |
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| 17:14 | for what they do. So excitatory you that's excitation synaptic means it's on |
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| 17:19 | other side of the synapse. In words, it's in the receiving |
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| 17:24 | All right. And it's a So, it's it's a membrane potential |
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| 17:28 | . That's where the name comes But because this is such a long |
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| 17:32 | . Years of words, we don't that. I mean, can you |
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| 17:34 | trying to say that all the No. So, what we do |
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| 17:36 | we call an E. P. . P. Alright, E |
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| 17:39 | S. P. S a lot . Right, Okay. So, |
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| 17:43 | an E. P. S. . But it's an excitatory post synaptic |
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| 17:46 | . So, what we're saying here's our neuron we're going to stimulate |
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| 17:51 | that axon terminal right down there and releasing this neurotransmitter because the opening of |
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| 17:57 | in the receiving cell, that's the synaptic cell. And what's going to |
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| 18:01 | is is when you open in islands . In other words, when sodium |
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| 18:06 | open sodium flows in. And what gonna do is we're going to move |
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| 18:10 | the resting potential and we're going to polarise. That's the PSP. All |
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| 18:16 | . Now. It's a great So, it means very magnitudes varying |
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| 18:20 | . All dependent upon the stimulus that causing that E. P. |
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| 18:24 | P. All right. So, is a sodium dependent deep polarization. |
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| 18:31 | right. In the PSP. now this is small. Deep polarization |
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| 18:36 | we reasonably stay small. Is because gonna need to understand how we're going |
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| 18:40 | produce an action potential. So, not enough to produce the next type |
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| 18:44 | signal. So, this is a localized deep polarization occurring someplace on this |
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| 18:53 | that we hope will eventually be strong to produce an action potential. All |
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| 19:00 | . But this is a local And what it's trying to do is |
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| 19:02 | trying to move towards that region right , which we term the axon hillock |
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| 19:07 | you remember on Tuesday, today's Right? All right. Don't know |
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| 19:15 | this isn't working. Try it Oh, that's why because it's not |
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| 19:21 | right thing. It would help if action. Right? All right. |
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| 19:27 | , that's the E. P. . P. If you have an |
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| 19:29 | sp, that's excitatory, you must in I PSP one that's inhibitory and |
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| 19:35 | it is. All right. I PSP. Alright, inhibitory post |
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| 19:40 | . Everything you've just learned about the P. S. P E. |
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| 19:43 | S. P is true for the . P. S. P. |
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| 19:45 | right. Channel is opening The difference is that the channel that's opening is |
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| 19:50 | going to be a potassium channel or channel. Now chlorine moves into the |
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| 19:54 | . So, what you're doing is making the sell more negative chlorine moves |
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| 19:58 | potassium channel potassium is moving out. the inside of the cell more negative |
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| 20:03 | that's why you see from rest, see this hyper polarization that takes |
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| 20:10 | All right. So, in what we're doing is basically saying we're |
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| 20:15 | further and further away from our resting potential and further away from deep |
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| 20:22 | That's what's going on here. All . Uh And that right. There |
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| 20:28 | be high. Just ignore this. all that stuff out useless. That |
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| 20:33 | just me copying the slides and you see the danger of copying slides. |
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| 20:37 | right. So, these are two events. I can either cause a |
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| 20:43 | polarization or I can cause uh I hyper polarization, but it's going to |
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| 20:48 | through two different pathways. Now. thing is, is that the PSP |
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| 20:54 | PSP are simply responses to two Talk from one cell talking to another |
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| 20:59 | . Alright, It's on the receiving side. And it's basically say, |
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| 21:02 | , I'm gonna de polarize because you told me to de polarize. I'm |
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| 21:05 | to hyper polarized because you just told to hyper polarize. But they're too |
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| 21:10 | . The PSP and PSP are too to cause the cell to really do |
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| 21:14 | . And so what the strategy here , is to allow a single cell |
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| 21:19 | respond to multiple signals coming in almost the time. And what we're looking |
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| 21:25 | the bottom of this picture as well the top is you can see here |
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| 21:28 | purple. It's a single neuron. then all those little blue things are |
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| 21:34 | axon terminals of many other neurons talking that one in the middle. In |
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| 21:39 | words, the purple cell is your synaptic neuron and then all the blue |
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| 21:44 | are the pre synaptic neurons. So blue is sending a signal to the |
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| 21:50 | . Now I understand I come from different generation than you guys and it's |
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| 21:55 | more and more obvious every day. right. So, I know many |
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| 22:00 | you guys do not use facebook. don't ever use facebook, but I'm |
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| 22:03 | I'm going to use social media as example here. All right. So |
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| 22:06 | is the social media that you guys ? So I can make this |
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| 22:10 | Yeah, instagram, twitter and tick . All right. Let's say you |
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| 22:19 | an influencer because you all are right? You have influence in other |
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| 22:24 | lives. And do people have other on your life? Yes. So |
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| 22:28 | are an influencer and you are dependent your millions of followers to determine what |
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| 22:33 | is that you're going to do. right, today, I am going |
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| 22:37 | do x or I'm going to do ? Right? I'm going to show |
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| 22:40 | how to put makeup on so that look like a kitty cat making up |
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| 22:45 | ? I don't know. Like I , I do not use social |
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| 22:47 | So whatever crazy thing you guys are nowadays, I don't know. All |
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| 22:53 | , But you're not going to just and do something, right? Because |
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| 22:56 | now dependent upon your followers to tell what to do. So what you're |
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| 22:59 | do is you're gonna say tomorrow I'm teach you this. You tell me |
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| 23:02 | you want to do. So you're to send a signal out there |
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| 23:05 | hey, here's a poll, tell what I should do. And so |
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| 23:09 | ask all millions of your followers to tell me what am I gonna |
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| 23:13 | Am I gonna do X. Or I gonna do? Why? So |
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| 23:16 | of the followers are going to tell to do X. Some of the |
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| 23:18 | are going to tell you to do ? Right? And depending upon which |
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| 23:21 | the greater signal you're gonna do Or why? Whatever it happens to |
|
| 23:25 | . Think of those neurons, the blue ones as being your followers and |
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| 23:30 | the purple one. All right. what are they doing? You have |
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| 23:34 | cells are sending signals that are gonna deep polarization. You're gonna have some |
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| 23:38 | that are gonna be sending signals that in hyper polarization. And what's gonna |
|
| 23:42 | is you're gonna look at which direction I go? In other words do |
|
| 23:47 | . D polarize or do I hyper when I take into account all the |
|
| 23:53 | that I'm receiving at any given And so those chips and dips the |
|
| 23:58 | of them becomes another alphabet soup. grand post synaptic potential, the |
|
| 24:05 | P. S. P. All . So the direction or the response |
|
| 24:12 | that cell, that purple cell is upon the grand sum of all the |
|
| 24:18 | . P. S. P. . And all the I PS |
|
| 24:20 | That it is receiving. All And what we do is we say |
|
| 24:24 | we're going to cause this sell the cell to respond, then we're going |
|
| 24:30 | have to sum up everything. And two different ways we can do this |
|
| 24:33 | temporal or spatial summation. And if amount of change that takes place in |
|
| 24:39 | self I. D. Polarized I'm going to reach a threshold that's |
|
| 24:43 | to cause the production of an action . But if I don't reach that |
|
| 24:49 | , then I get no action And so in other words, what |
|
| 24:52 | doing is I'm telling the cell I want you to tell the next |
|
| 24:58 | in the road what to do. is what the E. P. |
|
| 25:01 | . P. S and the I PS are doing their signals that are |
|
| 25:05 | in the production of a broader signal results in the message receiving to be |
|
| 25:12 | further down. All right, I'm just going to use these three |
|
| 25:16 | here since they're in the flashlight. right. So this is a pre |
|
| 25:20 | cell producing enough of a signal that this cell to tell that cell what |
|
| 25:26 | do. Does that make sense? , if this cell doesn't produce a |
|
| 25:31 | big enough signal to produce a signal , that cell is never going to |
|
| 25:37 | . And so what we're looking at is we're looking at a chain of |
|
| 25:40 | and how each of these cells produce signal. All right. So, |
|
| 25:46 | cell that's receiving the one here in middle, for example, is we're |
|
| 25:51 | at the G. P. P. Are there enough excitatory signals |
|
| 25:56 | cause deep polarization? Are there not signals to not cause a deep polarization |
|
| 26:02 | to reach this threshold? And we're to use it through these two |
|
| 26:06 | temporal and spatial submission. Yes, , I told you this stuff gets |
|
| 26:09 | little bit wonky here. Yeah. enough membrane neuron is getting more E |
|
| 26:17 | S. P S. No, . You get further and further |
|
| 26:21 | You get hyper polarization. So you further and further away from threshold. |
|
| 26:24 | it becomes even more difficult to reach . And that's actually a good observation |
|
| 26:29 | I did kind of skip over. , so, if you can imagine |
|
| 26:34 | , that's a point is a It's a measure of charge on the |
|
| 26:39 | of the cell. If deep polarization me closer to it, if I |
|
| 26:43 | hyper polarization that makes it further and away. So it becomes even more |
|
| 26:48 | for me to get to threshold. makes sense. Like part of this |
|
| 26:55 | bringing in. So the question is it really was a statement and |
|
| 27:00 | you're correct. The statement was so polarization czar always bringing me closer to |
|
| 27:08 | . The answer is yes, that true. All right. So, |
|
| 27:11 | I want to do is I want look at these two pathways, a |
|
| 27:14 | spatial summation. All right. And thing is it's not difficult. Come |
|
| 27:21 | there, we are. All It's not difficult. You just have |
|
| 27:23 | kind of take that step back and what we're looking at is right |
|
| 27:27 | we're thinking about one cell interacting with cell. All right. So, |
|
| 27:31 | going to use a clap as an of the E P S. P |
|
| 27:36 | being produced. All right. if this represents an E P S |
|
| 27:40 | , that's not very loud, is ? And so you can see in |
|
| 27:43 | first little area, this yellow area saying no submission. Think of each |
|
| 27:48 | those deep polarization as a clap. , you see a clap and you |
|
| 27:51 | another clap, right? Nothing Alright, basically, there's a certain |
|
| 27:57 | of sound being produced by my It's not very loud, but you |
|
| 28:00 | see the change. All right. temporal summation. What we're doing is |
|
| 28:04 | looking at two neurons firing at the time producing their own E P S |
|
| 28:10 | in the receiving sell each. All . So let's say they each have |
|
| 28:14 | own magnitudes. All right. It's clap is what I said. So |
|
| 28:17 | what happens when two people clapped I'm gonna clap once and then you |
|
| 28:20 | with me. Okay. Now to it louder? Yeah. So when |
|
| 28:26 | are added together you get a greater . So temporal summation deals with when |
|
| 28:32 | cells are producing a signal in that cells. So they're producing two |
|
| 28:37 | P. S. P. Which gets some together and it causes |
|
| 28:41 | to reach or get closer to Now, in the picture there showing |
|
| 28:44 | getting above threshold. All right. don't worry about that. That's just |
|
| 28:49 | artist. Right? It's just basically is small too, is bigger than |
|
| 28:55 | and it's because two of them are occurring at the same time. So |
|
| 28:59 | deals with firing. Right? Trying see if I have this, |
|
| 29:09 | Oh yeah, I did get it . All right. What I just |
|
| 29:15 | was spatial. All right. And reason how you separate these two |
|
| 29:19 | it's in the name, spatial means in space. So that's two or |
|
| 29:24 | temporal means closer together. So they're together in time. So let's back |
|
| 29:28 | up. Alright, spatial submission. one and then when two together you |
|
| 29:35 | she's right, you do it with 123 little bit louder. Okay. |
|
| 29:40 | three did it? 123, Try to get four whole class. |
|
| 29:50 | see a flatter. All right, spatial are we all the same |
|
| 29:56 | No. So more than one neuron an E P. S. |
|
| 30:01 | In the single receiving neuron. I got that your eyebrows are doing |
|
| 30:06 | . I was completely when you use backwards. So during spatial the only |
|
| 30:14 | in those no so special has to with the number of neurons involved. |
|
| 30:20 | that's that's why it's it's spatial. they both have a time component, |
|
| 30:24 | ? They're doing it at the same . But when you're dealing with spatial |
|
| 30:28 | more than its two or more neurons the word we're looking for temporal. |
|
| 30:34 | right. So let me explain temporal I cannot demonstrate this. I'm not |
|
| 30:38 | enough. But just bear with All right, temporal is when a |
|
| 30:41 | neuron begins to fire with greater All right. So here's the |
|
| 30:46 | right? There is the one sound , I'm not fast enough but you |
|
| 30:55 | see can you imagine it's going up it's not coming down but the next |
|
| 30:58 | is close enough that it keeps adding top of itself. So eventually you |
|
| 31:02 | something that becomes much much louder. , so temporal means one neuron firing |
|
| 31:09 | greater frequency. So the time and difference in time in which it's firing |
|
| 31:13 | shorter and shorter and shorter. So where you get the attitude. We |
|
| 31:18 | have something that's called cancellation and hear you do is you basically see uh |
|
| 31:23 | against the type of summation. But dealing with magnitudes ones of hyper polarization |
|
| 31:27 | polarization. Once a deep polarization. so when you add those two things |
|
| 31:31 | , they cancel each other out. , When you hear cancel, you're |
|
| 31:35 | of equal magnitude, but it doesn't to be equal magnitude. If you |
|
| 31:39 | something that's -10 and something that's plus , you're going to get -5. |
|
| 31:44 | ? That's still a canceling. They're in opposite directions. Yes, |
|
| 31:54 | you can have both. So, when we looked at that picture, |
|
| 31:57 | saw one neuron with thousands, I , the picture really was closer to |
|
| 32:02 | , but you can imagine all these uh acts on terminals terminating on that |
|
| 32:08 | cell. So, you might have cells talking at the same time. |
|
| 32:12 | might have one cell sending many many . All of these things. You |
|
| 32:15 | have one that's producing I PS PS that's producing E P S P |
|
| 32:18 | And so all of those things summed together collectively, is going to produce |
|
| 32:24 | response in that receiving cell. All . So, that's what the G |
|
| 32:28 | S P is is dependent upon the total of all the E P S |
|
| 32:33 | s and P S. P And we're not asking the question |
|
| 32:35 | how are we producing them? It's the big picture. All right. |
|
| 32:42 | , we're going to be using these temporal and cancellation. Should spatial temporal |
|
| 32:49 | plus cancellation to determine that G P . P. All right. So |
|
| 32:59 | moves us to the action potential. right. I'm gonna give away as |
|
| 33:02 | of the story? I usually try not give away the whole story at |
|
| 33:05 | beginning, graded potentials are used to action potentials there. I just gave |
|
| 33:10 | the story. All right. in essence, what I'm doing is |
|
| 33:13 | receiving a signal someplace on the cell or on the Dendrite. And that |
|
| 33:18 | is a short term wave or a distance wave. And if it's strong |
|
| 33:22 | , what it's going to do is going to reach the axon hillock and |
|
| 33:26 | it gets to the axon hillock in a strong enough deep polarization of the |
|
| 33:30 | hillock, I reach threshold and I an action potential. Okay, that's |
|
| 33:35 | goal of the G P. P. S. Alright, cannot |
|
| 33:39 | an action potential in the cell. , remember using our model, this |
|
| 33:43 | the first cell that produced the G . S. P in this |
|
| 33:47 | And what we're saying is can this PB strong enough to produce a signal |
|
| 33:52 | then communicates to this cell down Okay, now, your book uses |
|
| 33:58 | picture and I think it's kind of good way to look at it because |
|
| 34:01 | it does, it says when I at a graph, I need to |
|
| 34:05 | for where changes occurring and what they is they have marked off where all |
|
| 34:10 | changes occurring and they did it All right. So, whenever you |
|
| 34:15 | a graph and you're looking at it a line graph, you've got to |
|
| 34:18 | the question. All right. What this graph telling me? It's telling |
|
| 34:21 | there is change going on at very points. I just got to look |
|
| 34:25 | see where the points are changing. if you look at this graph, |
|
| 34:28 | it has, it has two parts it. And you're sitting there |
|
| 34:31 | I didn't want to take a biology . Just tell me how the body |
|
| 34:35 | . All right. Down on the . We have time up here. |
|
| 34:38 | have voltage. All right. And , what you're looking at is you're |
|
| 34:42 | at a graph over a period of . In other words, what we've |
|
| 34:44 | is we've taken a probe and we've it in the cell. And we |
|
| 34:47 | , what is going on at this in the cell? Over time we |
|
| 34:51 | to see the change of the membrane . And so what we're looking at |
|
| 34:54 | we're basically saying it is going through massive deep polarization and then it comes |
|
| 35:00 | through a quick re polarization, spends little bit time of hyper polarization, |
|
| 35:04 | returns back to rest at this particular over time. And what we're looking |
|
| 35:10 | is a waveform. All right. , over time, this is what |
|
| 35:15 | from kind of looks like it goes and then it comes back down |
|
| 35:19 | You got that kind of right the action potential is a much much |
|
| 35:27 | membrane potential change. It has all unique kind of characteristics. Alright, |
|
| 35:32 | we're going to get to the big . The thing that results in this |
|
| 35:37 | potentials are specifically voltage gated. So responding to a change of membrane |
|
| 35:43 | Where do we get the membrane potential from the grated potential that causes a |
|
| 35:48 | to open. So, it's going be the sodium channel or potassium |
|
| 35:52 | So, if I get a deep , that's a result of opening up |
|
| 35:55 | voltage gated sodium channels, right, comes in. I'm gonna get deep |
|
| 35:59 | . Re polarization is going to be of the first channel. Opening up |
|
| 36:02 | the second channel. Now, we're to walk through all of this. |
|
| 36:07 | , if you're like, wait a , I'm not entirely on board |
|
| 36:10 | I'm not sure where we are. panic. Just shit. If I |
|
| 36:13 | through 15 slides and you're still I don't get it, then |
|
| 36:18 | Right, well, you don't have panic. So, I want to |
|
| 36:20 | show you first the two channels. right. And the reason I want |
|
| 36:25 | show you these two channels because they're simple. One of them simple. |
|
| 36:28 | of them is a little bit more . What we're looking at here in |
|
| 36:31 | particular picture is a voltage gated sodium . It has two gates. If |
|
| 36:35 | look at this door arrived here, say there is one gate. But |
|
| 36:39 | you look on the other side on other side of the channel, you |
|
| 36:42 | see there's another door, right? an actual little tiny hallway there and |
|
| 36:45 | two doors and that's kind of what voltage gated sodium channel is. It |
|
| 36:49 | two doors to it. The first is called an activation gate. The |
|
| 36:53 | door is called an inactivation gate and exists in three states. If you |
|
| 36:58 | two doors, there must be three have one door. There's two |
|
| 37:02 | What are the two states in one situation? Open closed. Right. |
|
| 37:06 | right. So with two doors, three states. And the reason we |
|
| 37:10 | about these three states is because you to go 123 and in order to |
|
| 37:16 | , you go all the way back one again. You don't get to |
|
| 37:19 | back to two. You have to 123 and then come all the way |
|
| 37:22 | to the beginning. All right, I am the gate. I looked |
|
| 37:27 | like one. Right, here's my gate. Here's my inactivation gate. |
|
| 37:32 | right. In the first state I'm , but I'm capable of opening. |
|
| 37:38 | here's my activation gate. I'm closed I'm capable of opening. Here's my |
|
| 37:43 | gate notice which stated send right, down, it's gonna allow stuff |
|
| 37:48 | So if I get stimulated, I up the activation gate ions can flow |
|
| 37:53 | . But the moment I open up gate, this gate begins to |
|
| 37:57 | It's just a little bit slower. ? So this one opens up on |
|
| 38:00 | one slowly closes. So I got three states here. I'm close but |
|
| 38:04 | of opening. Now I've opened and this one closes slowly. So now |
|
| 38:10 | back closed and incapable of opening. I have to be reset. So |
|
| 38:15 | happens is is magic And then this opens up and that's where I'm back |
|
| 38:19 | this. There's no going back to center stage. So 123 is how |
|
| 38:24 | have to go then automatic reset. right, so closed, but capable |
|
| 38:30 | opening. That's first one opened and I'm inactivated or closed but incapable of |
|
| 38:35 | have to be reset. Those are three states. All right. |
|
| 38:39 | why do I tell you this? I mean and cruel. And I |
|
| 38:42 | to make you look at molecular biology it's fun and wow. Right. |
|
| 38:46 | , it's because it's going to help understand what's going on in that action |
|
| 38:50 | . All right. That's why we that's why we look at it. |
|
| 38:53 | other type of channel voltage gated potassium . Simple has one gates exists in |
|
| 38:57 | states. What are the two states open and closed? Easy. All |
|
| 39:04 | . So, Oh yeah, Back our picture of the action potential. |
|
| 39:10 | right. And what we're gonna do we're gonna walk through the different |
|
| 39:13 | So down here. Remember we had the different colors and stuff. |
|
| 39:16 | we're just gonna look at 123456. gonna walk through them like that. |
|
| 39:20 | right. So, the color you down here is gonna show you which |
|
| 39:23 | are open. Which channels are That's what this is going on is |
|
| 39:27 | to show you the degree of All right. So, remember what |
|
| 39:31 | said, is that a membrane at is predominantly permissible by which type of |
|
| 39:37 | , which is the most which ion moving more. Mhm, potassium |
|
| 39:42 | Remember, there's a domination by potassium is still coming in, but potassium |
|
| 39:47 | really coming out. So, that's the inside of the cell is more |
|
| 39:51 | . All right. And so, rest, that's what's going on. |
|
| 39:54 | just taking advantage of those leak All those voltage gated channels that I |
|
| 39:58 | showed you are all closed. They're active. They're not doing anything. |
|
| 40:01 | waiting for membrane potential change in order open. So, any sort of |
|
| 40:06 | you're seeing right now are leak And then those sodium potassium pumps |
|
| 40:10 | And then, you know, I'm you back where you started and then |
|
| 40:13 | comes back in. Then you go where you started. That's why we're |
|
| 40:15 | that membrane potential of -70 at Alright, so, that's what's going |
|
| 40:20 | here. That's our starting point at -70 Leak channels. Only potassium |
|
| 40:29 | And that's why we're at the 70 cell over here, remember told the |
|
| 40:41 | cell fire and produces any PSP the . P. S. P. |
|
| 40:46 | going to travel along the length of of the cell body and it's going |
|
| 40:49 | get to the axon hillock because this where we're going to produce the action |
|
| 40:53 | if it's going to be produced. right. So what's going to happen |
|
| 40:57 | is that when that E. S. P. Or that deep |
|
| 41:01 | reaches the axon hillock? What it's do is it's going to cause a |
|
| 41:06 | potential change that causes some of those gated sodium channels to open. Right |
|
| 41:12 | potential chain cause voting sodium channels to . If sodium channels open, I'm |
|
| 41:20 | deep polarization which causes more channels to . Which causes more sodium to come |
|
| 41:27 | . Which causes more channels to which causes more sodium to come |
|
| 41:31 | You see what we have here? a feedback loop. What kind of |
|
| 41:35 | loop, positive. Right? It's a snowball. Right, Take a |
|
| 41:39 | , put it on the hill, gonna start rolling down the hill, |
|
| 41:41 | up more stone is gonna get bigger bigger and bigger and bigger. All |
|
| 41:44 | . So, if we can get PSP to reach the axon hillock, |
|
| 41:49 | gonna happen is we're gonna start opening voltage gated sodium channels. We're going |
|
| 41:54 | flip, in essence, the In other words, it's going to |
|
| 42:00 | off being potassium being the dominant. what we're doing is we're slowly bringing |
|
| 42:04 | sodium All right. And so this what's going on that trigger events causing |
|
| 42:10 | deep polarization. Opening up the voltage sodium channels causes sodium to come |
|
| 42:13 | which is a greater deep polarization. this is that turning. And so |
|
| 42:17 | why we start seeing this thinks growing . So you're starting off flat and |
|
| 42:23 | off you go up like this. you've opened all the voltage gated sodium |
|
| 42:30 | , you've reached threshold. You can't any more. But now, what |
|
| 42:35 | do is you're now dominating the membrane of the membrane by sodium coming in |
|
| 42:42 | potassium going out. You've literally flipped . And so that's why we see |
|
| 42:47 | the next step, this massive We've reached threshold. That threshold being |
|
| 42:53 | opened up all the channels. So threshold isn't a point that we |
|
| 42:59 | voltage wise, it's a point that labeling as this is when this happens |
|
| 43:04 | it just happens to be at this voltage. Okay, It's kind of |
|
| 43:09 | chicken and egg explanation, right? not. So when you reach the |
|
| 43:15 | when all those volts educated channels, sodium voltage gated channels open your at |
|
| 43:22 | . All right now, I say , it's all. And so now |
|
| 43:29 | you're dealing with, you're dealing with permeability domination. It's almost 1000 fold |
|
| 43:35 | . And so that's why you're massively . Now we talked about just |
|
| 43:40 | I'm not going to see if I'm see if anyone remembers, Do you |
|
| 43:42 | the point at which sodium stops going the cell? Remember the number Close |
|
| 43:49 | but you're right. Well, I you to pick up. It's about |
|
| 43:52 | 60. All right. That's So, what are we doing |
|
| 43:57 | And so if nothing else were to , sodium would keep going in and |
|
| 44:02 | deplore Ization would occur until you get plus 60. But does that graph |
|
| 44:06 | you hitting plus 60? No, about plus 30. And the reason |
|
| 44:11 | sodium is rushing in is because all channels are open. So something happens |
|
| 44:16 | there at the top that says sodium come rushing in anymore. What do |
|
| 44:20 | think that is? I've already told no thresholds down here. That's good |
|
| 44:29 | . What type of channels do we ? Yeah, I hope so. |
|
| 44:33 | how many gates does it have? ? And what do we know about |
|
| 44:37 | second gate? It closes slowly, its signal to close at the same |
|
| 44:42 | that we open. So, what really dealing with here, sorry, |
|
| 44:48 | actually two events. So at the of the peak there. So at |
|
| 44:52 | 30 million volts. That's when those channels begin to close. So remember |
|
| 44:57 | what we did. This is at . We went open and then during |
|
| 45:01 | period of rapid deep polarization we're open we're slowly closing. And then at |
|
| 45:07 | top we're closing. So really what looking at is we're looking at event |
|
| 45:12 | takes place over time, right? instead of thinking about going up and |
|
| 45:16 | , think of it going left and . So at this point right |
|
| 45:21 | that's where opening at this point, there, That's when we're closing. |
|
| 45:26 | , It's a time dependent event. , all things being equal, |
|
| 45:32 | If nothing else were to occur then sodium would leak back uh would slowly |
|
| 45:38 | into the channel, but more potassium leak out. And so eventually you |
|
| 45:42 | go up, up, up, , up, up, up, |
|
| 45:44 | any return back to rest. But not what happens. We shoot right |
|
| 45:48 | down and the reason it shoots straight down to go through this re polarization |
|
| 45:53 | because one closing of the sodium But to opening of the potassium |
|
| 45:58 | Now, when do we open up signal to open up the potassium |
|
| 46:01 | A lot of people would say, it's right up here when that thing |
|
| 46:04 | that peak, it's actually at the point a threshold. The difference is |
|
| 46:09 | potassium channels are like your friend, slow friend. You know which one |
|
| 46:14 | talking about? The one you tell joke to? And they kind of |
|
| 46:17 | at you for a minute and then about two minutes later, that's when |
|
| 46:21 | start laughing, You're now picturing this of yours, right? That's what |
|
| 46:26 | potassium channel is. It's like here's gag and it kind of sits there |
|
| 46:30 | stares for a second says, oh I get it. That's when it |
|
| 46:34 | up. So suddenly sodium channels It got the joke, potassium didn't |
|
| 46:39 | the joke. And so that's what's at the top. sodium is |
|
| 46:47 | potassium is opening and so we see rapid fall and it's his re polarization |
|
| 46:54 | because it's your slow friend. All . It's also not only slowly opening |
|
| 47:00 | slow in closing. And so instead just stopping right here at rest and |
|
| 47:06 | off we go. It takes a for those too close. And so |
|
| 47:10 | state of hyper polarization, I guess looking at something not there yet. |
|
| 47:16 | , I'm gonna go ahead and tell this and then I'll come back to |
|
| 47:19 | picture. All right. So, state of hyper polarization right here is |
|
| 47:23 | function of those channels taking their sweet to close. And so that's why |
|
| 47:28 | not stopping at rest and coming That's why you hyper polarized. And |
|
| 47:33 | the return back to the resting potential a result of the sodium potassium HBs |
|
| 47:39 | going no, no, no, . I want you over here and |
|
| 47:41 | starts returning back to their original All right. So, the reason |
|
| 47:46 | shoot low is because the sodium channel excuse me, the potassium channels are |
|
| 47:51 | slow. All right. I'm going go back and just kind of show |
|
| 47:55 | this All right. This is to you see what's going on with regard |
|
| 48:01 | that bulge educated sodium channel. All here. You can see it's in |
|
| 48:05 | closed state there you're at rest stimulation along opens up that channel. We're |
|
| 48:10 | to see deep polarization and then what's is during that hyper or that that |
|
| 48:16 | depressurization event. Both channels are open then bang we close. That's why |
|
| 48:21 | going back down again. All And again, we're helped with this |
|
| 48:25 | here because we also have that second . So it's not just me. |
|
| 48:31 | Well, I want you to learn biology. There's a reason why we |
|
| 48:35 | about these things so that you can how the cell is managing this action |
|
| 48:41 | . How is it producing it? does it make something different than the |
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| 48:45 | potential? It's because of the presence these particular types of channels. |
|
| 48:52 | an action potential moves. All We looked at this and we said |
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| 48:57 | it's a wave. All right. what we said is when we look |
|
| 49:00 | that graph, we're basically looking at single point and saying what's happening here |
|
| 49:04 | this single point. We're basically watching polarization goes up and it comes back |
|
| 49:08 | . So wave have you ever done way Yeah. Have you done the |
|
| 49:15 | ? Have you ever done the See a lot of people do the |
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| 49:18 | sporting events. We don't do the the sporting events at the University of |
|
| 49:25 | , excited about science? So we the wave in the classroom, you're |
|
| 49:30 | , I don't want to be She's sitting in the front going, |
|
| 49:34 | cannot believe I sat in the splash today. All right, we're gonna |
|
| 49:37 | the wave now. You don't have stand up to do the wave wave |
|
| 49:39 | really, really simple. All you do is do it like that, |
|
| 49:41 | ? And I want to show you a wave does. We're all going |
|
| 49:45 | participate looking out over there because they're cool for school. They think if |
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| 49:51 | started over here, they don't have do it. But you all |
|
| 49:55 | We keep doing it, we all it ready. Here we go, |
|
| 49:59 | . And look what happens. You how propagates once a wave starts, |
|
| 50:04 | continues all along. Now, I you to picture for a moment that |
|
| 50:07 | guys are the cell. And what's here is I was that stimulus that |
|
| 50:13 | in the opening of all those And so once we reach that |
|
| 50:17 | boom, we got an action potential moved all the way along the length |
|
| 50:21 | the, of the classroom. That's what this is trying to show |
|
| 50:26 | . So when we're looking at that , we're literally saying here at this |
|
| 50:31 | , we're going to see what the potential looks like, But really what |
|
| 50:35 | doing is we're just catching a moment time to watch at this particular |
|
| 50:40 | what's happening along the entire length as wave travels? Okay, So it's |
|
| 50:46 | propagated event. It starts at the hillock and it's going to go the |
|
| 50:51 | length of that axon until it gets to the axon terminal. All |
|
| 50:56 | It's a long distance signal to get one side of the cell to the |
|
| 51:00 | . And we already mentioned how long the sell? Well. In some |
|
| 51:04 | it could be as the longest three . Right. What's that? I |
|
| 51:12 | just wondering if uh that's a great . Is there any loss along the |
|
| 51:21 | ? No. And this is one the key features of an action |
|
| 51:27 | I don't even have it on That's on another slide. Apparently there's |
|
| 51:31 | rule in an action potential. It's all or none response. Okay. |
|
| 51:36 | we call it the all or none , it's probably on to slides |
|
| 51:39 | I thought it was on here. it's all or not in essence what |
|
| 51:43 | is. It says if I create greater potential inside a neuron cell body |
|
| 51:51 | causes me to reach threshold in the potential, then I'm going to get |
|
| 51:56 | full action potential at the axon hillock then it's going to be propagated along |
|
| 52:02 | entire length and it's going to stay same height and the same strength the |
|
| 52:08 | way. All right. If I reach threshold then I don't get |
|
| 52:14 | So all or none. It's very . All right. And what we're |
|
| 52:20 | is we're basically just going through the over here, we're gonna start first |
|
| 52:23 | the sodium channels opening and then the area causes the next area to open |
|
| 52:26 | with a bunch of sodium channels behind , potassium channels open up the sodium |
|
| 52:30 | closed. And that's why propagates in way. So, if you know |
|
| 52:34 | different parts of that curve, you what's going on and why it's propagating |
|
| 52:39 | . Just like you when you are the wave, you're watching the people |
|
| 52:43 | on this side of you and you're the question, what is going to |
|
| 52:45 | my turn? Right? And then it got next to you, when |
|
| 52:49 | person was up here, that's when started right. And then you went |
|
| 52:52 | and then the person next to you doing the exact same thing. |
|
| 52:56 | what's happening at this point is depending what happened to the point before and |
|
| 53:00 | going to have an effect on the after. And that's why you're seeing |
|
| 53:03 | propagation. It starts at the axon and it progresses the entire way. |
|
| 53:09 | an action potential moves in one Notice when we started the wave, |
|
| 53:14 | started over here and went that Didn't go up the room and then |
|
| 53:17 | this way, it went only in direction. All right. Action potentials |
|
| 53:22 | the same way. They only move a single direction. Greater potential. |
|
| 53:26 | could go in any direction. It's like that ripple. We throw |
|
| 53:30 | rock in and then get a ripple the point of stimulation, axe potential |
|
| 53:34 | the point of stimulation travels in one . The reason for that, we |
|
| 53:37 | this a refractory period. The reason that is that sodium channel that we |
|
| 53:41 | about Because exists in three states One open, capable closed, capable |
|
| 53:46 | opening state to open state. three , but incapable of opening. All |
|
| 53:54 | . So, I want you to about this being the cell again. |
|
| 53:58 | right. This is the axon over . The action potential has just passed |
|
| 54:03 | here. The action potential in motion it's going in this direction. |
|
| 54:07 | what is going on with the sodium here? What state are they in |
|
| 54:14 | , incapable of opening? They have be completely reset. So, I |
|
| 54:18 | travel this direction because I can't make channels open. I can only travel |
|
| 54:23 | direction where the sodium channels are available open. And so that's why we |
|
| 54:28 | this refractory period. This area, region on the membrane that is incapable |
|
| 54:33 | being stimulated. That's what the refractory refers to. It basically says the |
|
| 54:38 | of time in which an action potential be produced under any circumstances, no |
|
| 54:43 | the type or the strength of the the stimulus. Now, there are |
|
| 54:48 | parts to it. All right. is what is referred to as the |
|
| 54:51 | and the relative the absolute is when have those sodium channels and their close |
|
| 54:55 | , or even in the open Alright, if I'm if I've opened |
|
| 54:59 | every sodium channel, is there any of state of any amount of stimulation |
|
| 55:03 | of opening up any more sodium I'm glad you shook your head. |
|
| 55:07 | . If all of them are I can't open anymore. Right. |
|
| 55:12 | , there's no amount of stimulation that I can produce more on top of |
|
| 55:17 | where all has occurred. All So, that's part of the |
|
| 55:21 | The other part of the absolute is period of time when the sodium channels |
|
| 55:24 | closed and have to be reset. no amount of stimulation that's gonna make |
|
| 55:30 | reset any faster. There's nothing no that's gonna allow me to go through |
|
| 55:34 | process of resetting all the way to beginning. So, under those |
|
| 55:39 | when those two states, and remember where those two states are, |
|
| 55:44 | this area right here in this right here. So, these two |
|
| 55:47 | would be absolute refractory period because I stimulate the cell anymore to get those |
|
| 55:55 | to open the relative refractory period. the other hand, is when an |
|
| 56:00 | potential can be stimulated. But you're need a stronger stimulus. Now, |
|
| 56:05 | this case, the sodium channels are to be in the uh they're going |
|
| 56:09 | be transitioning from the closed but incapable opening to the closed to capable of |
|
| 56:14 | state? All right. So, can open them. All right. |
|
| 56:19 | we have that problem of those slow channels. They're already still in the |
|
| 56:24 | state. They haven't gone through the state yet. That's why we are |
|
| 56:27 | a hyper polarized state. So, have to have a stimulus that's strong |
|
| 56:33 | to overcome the hyper polarization to get up to that point a threshold. |
|
| 56:40 | right. Put that in english. it took 10 million volts or |
|
| 56:44 | 15 minutes to get from the rest their 15 million volts at the bottom |
|
| 56:49 | that pit is not going to be to get to threshold. I'm going |
|
| 56:52 | need more stimulation to get into that . So, it takes more |
|
| 56:58 | But I can do it. She's have to be a bigger, bigger |
|
| 57:03 | . All right. So, we to overcome the states of those channels |
|
| 57:10 | order to get another action potential. , the reason we have all this |
|
| 57:16 | why we have a refractory period is the way that our brains and our |
|
| 57:21 | system encodes information is in the frequency action potentials. We remember what we |
|
| 57:28 | is graded potentials can be summed. you remember that? We have temporal |
|
| 57:33 | , spatial summation. And we have . Action potentials are all or |
|
| 57:39 | So, that means I can't take action potential stack on top of another |
|
| 57:43 | potential. So, how do I if something stronger? Right? How |
|
| 57:47 | I know if that needle that I in you is being done harder |
|
| 57:53 | It's in the frequency of the action as well as the number of cells |
|
| 57:59 | are being stimulated. That's how your understands. Information is encoded in the |
|
| 58:05 | of action potentials. So, it's another picture showing the refractory period. |
|
| 58:12 | showing you it's limiting the direction in the action potential can go. |
|
| 58:24 | how do we speed up and slow action potentials? All right. This |
|
| 58:29 | where we have to understand a little about? No, I don't know |
|
| 58:35 | that go boom. You know what cars I'm talking about? You get |
|
| 58:38 | them. Their phone thumb, thumb . All right. You wanna have |
|
| 58:42 | car like that? It's okay. not gonna be mad at you. |
|
| 58:46 | just gonna All right. We got . Huh? You do. |
|
| 58:49 | All right. Oh, you got got a car that goes, did |
|
| 58:52 | do it yourself or? Okay. type of wire did you use when |
|
| 58:56 | made the cars that go boom? lose a little thin wires. Did |
|
| 58:58 | get big thick wires, huh? thick ones. Why do you |
|
| 59:04 | Because he told you to uh this why we have to know a little |
|
| 59:09 | of physics. Right? All So, here's the deal with |
|
| 59:13 | The thinner the wire, the more and more resistance, the harder it |
|
| 59:17 | to get signals or electrical impulses through . All right. So, diameter |
|
| 59:22 | . All right. So, you a signal to travel quickly and fast |
|
| 59:28 | a wire? You make a bigger . All right. So, |
|
| 59:31 | really powerful stereo systems are going to big thick wires. All right. |
|
| 59:37 | , look at your body. All . You're filled with wires. |
|
| 59:41 | neurons acts on nerves whichever way you to think about it. All |
|
| 59:45 | Now, in order to get a from my little toe when I step |
|
| 59:48 | that little tiny rock or that Right, I want that signal get |
|
| 59:52 | to my brain. So, what I want? I want a big |
|
| 59:54 | wire. But if I have a thick wire, my body is finite |
|
| 59:57 | terms of the volume inside it. , I'd have to increase the volume |
|
| 60:01 | my body. Which means I'd have have a longer wire, which means |
|
| 60:04 | have to have a thicker wire, means I'm gonna have to have a |
|
| 60:06 | body. And you see the problem comes here, right? It basically |
|
| 60:10 | this the cycle of of making me and bigger and bigger as I go |
|
| 60:14 | . So, thickness matters. The the wire, the faster things |
|
| 60:18 | But there's a limit to how thick can get a wire. So, |
|
| 60:21 | we have is we have another mechanism my Ellen. All right now, |
|
| 60:25 | Ellen is a form of insulation is a cell that wraps itself around the |
|
| 60:30 | of an ax on right. And a zone where action potentials cannot |
|
| 60:37 | All right. And so what happens is we're gonna skip over those areas |
|
| 60:42 | the Myelin is all right. And doing so we're going to speed up |
|
| 60:47 | propagation of an action potential. I want to do that just yet. |
|
| 60:52 | we are. Right. Thanks. , this is all the stuff you |
|
| 60:59 | to know for the exam. All , hold on here. I don't |
|
| 61:04 | why. Come on. Oh All right, let's I'm gonna end |
|
| 61:10 | show for a second and I'm just to go right back to where I |
|
| 61:13 | to be. I'm not stopping I'm just moving where? Who is |
|
| 61:19 | I'm looking for. Oh, come . Of course that would happen. |
|
| 61:27 | . There we are. Back to show. That's going to look really |
|
| 61:32 | in the video Because I think it records four frames per second. So |
|
| 61:37 | just gonna be like they're all over place. So the question was, |
|
| 61:46 | the naked neurons basically ones without my , where do they exist? And |
|
| 61:50 | everywhere. So we're going to take of both. Yes, ma'am. |
|
| 62:02 | . So, I think I'm hearing question saying is when the action is |
|
| 62:08 | action potential doing something is that kind Right. So we haven't quite got |
|
| 62:14 | yet. So basically if I tell that, I mean it may make |
|
| 62:19 | but I don't want to give up done it yet. That makes |
|
| 62:23 | So I'm hoping only putting it on edge of your seat. This is |
|
| 62:26 | exciting story about how we make my wiggle. Okay. That's stupid. |
|
| 62:33 | we'll get there I promise. And I don't well we'll blame it on |
|
| 62:38 | Rolex thing. All right. So is an example of my own. |
|
| 62:41 | are two types of my alan. right. They're different in the peripheral |
|
| 62:45 | system. In the central nervous If you don't know the difference between |
|
| 62:48 | . Yeah. We haven't talked about central nervous system of the brain and |
|
| 62:50 | spinal cord peripheral is everything else. right. And so what we have |
|
| 62:54 | is we have cells and you can what have they done is they've wrapped |
|
| 62:58 | around the acts on and you can there's a little tiny gap or space |
|
| 63:02 | between the points of my Ellen. right. The purpose of the Myelin |
|
| 63:07 | to cover up and hide portions of axon. And so what's going to |
|
| 63:13 | then? Is that action potentials can occur in those points where there is |
|
| 63:18 | my Ellen. Alright. That's called note of ranveer which is the next |
|
| 63:23 | . Please work. Okay. All . So you can see here this |
|
| 63:29 | an all good inter site. This the natural um aside or the Schwann |
|
| 63:32 | and peripheral nervous system. You can there's a little tiny space, little |
|
| 63:35 | space, little tiny space, little space here. Is it blown |
|
| 63:38 | And so there's that little tiny The distance between here and here are |
|
| 63:42 | enough that an action potential can step the Myelin. Okay, there are |
|
| 63:49 | enough apart. So that actually has effect. And so this is akin |
|
| 63:54 | what we're going to see in terms how conduct well, it's akin to |
|
| 63:59 | walking. All right, So the I want to use here. So |
|
| 64:04 | clear here, neural inside is going be in the peripheral nervous system. |
|
| 64:08 | use individual cells. So, these each 123 cells. In our little |
|
| 64:12 | here here in the central nervous In a single cell. One to |
|
| 64:17 | all sorts There's lots of all meaning many danger site meaning many |
|
| 64:22 | All right, so, it's that of Ranveer and what it does, |
|
| 64:26 | means that uh propagation is going to differently in a cell that has the |
|
| 64:31 | Nation versus one that we were calling naked cell. So, I'm just |
|
| 64:35 | show you really quick a propagation in naked neuron, in other words, |
|
| 64:40 | no Myelin is like walking total Right. I have to cover the |
|
| 64:44 | length because along the entire length the are those voltage gated channels. So |
|
| 64:50 | all going to open and close in . Just like when we did the |
|
| 64:53 | right? Every person in here did of the wave as you went |
|
| 64:57 | So the wave was continuous along the length. And so that's what contiguous |
|
| 65:04 | continuous propagation is. All right. basically like walking total hill. |
|
| 65:09 | if I'm walking to the hill, can get to that wall. But |
|
| 65:13 | there very fast. I mean, , I can do this. This |
|
| 65:16 | about as fast as I can Alright. Is usually where I do |
|
| 65:20 | race. You wanna race me? , you wanna race me? |
|
| 65:23 | Come on up what I want you to do as I want you to |
|
| 65:30 | normally. All right. And we're race to that second uh thing |
|
| 65:35 | Mark get set go. Yeah. . Mhm. Now, just to |
|
| 65:43 | it's not a flip. Let's do again. Just Mark Sit. I'm |
|
| 65:51 | going to win. Thank you. have a seat. All right. |
|
| 65:54 | , why was he able to go than me? Right, Because his |
|
| 65:59 | was allowing him to take steps over of the floor. Right? He |
|
| 66:04 | have to cover every inch of the like I did when I'm walking toe |
|
| 66:07 | heel instead, he's skipping over portions the floor, which allows him to |
|
| 66:12 | faster. All right, that's kind what salvatori conduction is. It's literally |
|
| 66:18 | from note of rand beers. A of ranveer to note of rand beer |
|
| 66:22 | again, for those of you who keen understanding this, this is the |
|
| 66:27 | of ranveer. The Myelin no action . All right. So you're hopping |
|
| 66:32 | one to the other and they're close together to allow you to be able |
|
| 66:36 | , if your gate is too can't do much. Right, There's |
|
| 66:41 | lot of work and you're not going move as fast. It's a visual |
|
| 66:46 | . Right? So the idea here we have some cells that are going |
|
| 66:51 | use contiguous or continuous uh conduction. are the ones that you don't need |
|
| 66:56 | quickly. Right? They can be and slow is a relative term when |
|
| 67:02 | talking about the nervous system. Or if you have to have something |
|
| 67:07 | fast, you're going to use And if you're really fast, |
|
| 67:12 | what are you gonna do? You're get better axons. Right, big |
|
| 67:17 | wires plus my island. So you have different speeds based on both diameter |
|
| 67:23 | well as the presence of my that's the idea and conduction, it's |
|
| 67:28 | to change. So this is just example of the contiguous conduction. |
|
| 67:33 | you can see it's entire length. it's this area in this area and |
|
| 67:37 | area, let's just keep moving forward story conduction. Again, statutory literally |
|
| 67:43 | to jump, that's where it comes . And so it's literally jumping over |
|
| 67:48 | Myelin to each note of ranveer along way. All right. You're skipping |
|
| 67:55 | the areas of myelin. There's just picture showing you that again right |
|
| 68:05 | why do we do this? we're able to conduct a lot faster |
|
| 68:10 | you saw. Also consumes a lot energy. When I'm doing south story |
|
| 68:16 | , I have to move a lot ions back and forth. If I |
|
| 68:18 | have small regions, I don't have move as many ions. So it's |
|
| 68:22 | , much easier. All right. , to answer the question about the |
|
| 68:30 | toe. Yes. Like you're on day. Yeah. So typically |
|
| 68:37 | the uh I r sorry not an is going to be my own aided |
|
| 68:42 | it's not you're not going to switch the two states. Now, developmentally |
|
| 68:47 | , you start off as all being . In other words, they're not |
|
| 68:51 | my elevated. But there are certain that are destined to become my |
|
| 68:55 | There are certain neurons that are destined never be my elevated. It's a |
|
| 68:58 | question. All right, let's come the last question that hopefully will answer |
|
| 69:05 | the big toe. Now, we've narrowly focused on what's going on inside |
|
| 69:11 | cells. Right, great potentials. potentials. Is this idea that these |
|
| 69:15 | just electrical signals, movement of ions signals over distances are very short |
|
| 69:21 | Alright. But ultimately what we're talking is two cells talking to each |
|
| 69:25 | All right. Remember what we said we had one cell releasing chemical that |
|
| 69:30 | another cell that causes an epi sp ? Or PSP. So, it's |
|
| 69:35 | once I was talking to the next result in a long distance signal down |
|
| 69:40 | length of the cell. All And so, where we have those |
|
| 69:44 | cells talking to each other? That what is referred to as a |
|
| 69:48 | Now, when we think nervous we think electrical, we think about |
|
| 69:52 | and greater potential. But the truth is that the cells, for the |
|
| 69:55 | part with a very very small very small minority. Most of the |
|
| 70:00 | communicate with chemicals. All right. releasing a chemical what we call a |
|
| 70:05 | transmitter to stimulate the next cell to that channel or cause that channel open |
|
| 70:11 | produce the E. P. P. Or the I. |
|
| 70:12 | S. B. All right. , this is what is referred to |
|
| 70:15 | the chemical synapse. The neurotransmitter in pre synaptic cell. So, if |
|
| 70:20 | synapse is that relationship between the The cell that's receiving or sending is |
|
| 70:25 | the pre synaptic cell. The Celtics is the post synaptic cell. All |
|
| 70:30 | . So, the neuro transmitter is released by the pre synaptic cell. |
|
| 70:34 | neurotransmitter crosses the synaptic cleft and it to a receptor on the post synaptic |
|
| 70:42 | producing the PSP or the PSP It's the name post synaptic. |
|
| 70:48 | right. So these are the four and I want you to see what |
|
| 70:52 | done now is we've we've taken a . It's more of a chicken and |
|
| 70:55 | question and we've kind of come back circle. All right. So that |
|
| 71:01 | potential was traveling on, traveling along it moved down the length of the |
|
| 71:05 | and it's now arriving down here at axon terminal and the axon terminal. |
|
| 71:11 | have volt educated channels but they're not gated sodium or bolt educated potassium |
|
| 71:18 | Those channels are specific for the conduction the action potential. Alright, the |
|
| 71:24 | potential is a signal that's an electrical . And so that electrical signal needs |
|
| 71:29 | be received by something on that receiving . So, it's a voltage gated |
|
| 71:33 | that opens. It's a different type channel. It's a calcium channel and |
|
| 71:37 | calcium is allowed to come inside the . And what it does that binds |
|
| 71:43 | um these molecules that are part of vesicles, we're not gonna go |
|
| 71:47 | What specifically is there? That's that and snap stuff that we talked about |
|
| 71:51 | earlier. Remember snaps. Don't if don't don't worry about it. All |
|
| 71:56 | . But remember the calcium comes in it causes these vesicles to merge with |
|
| 72:03 | synaptic membrane on the pre synaptic cell basically causes it to release that |
|
| 72:10 | That chemical signal. All right. chemical, whatever the neurotransmitter is then |
|
| 72:16 | into the synaptic cleft. Some will out. Some will get chewed |
|
| 72:19 | some will get absorbed. but some those will get across that synaptic cleft |
|
| 72:25 | they're going to bind to the receptor the post synaptic cell. And then |
|
| 72:29 | going to cause the channel open which the PSP. And the I. |
|
| 72:33 | . Be in the next cell. what we have now is we have |
|
| 72:37 | cell that is producing an action potential produces a hopefully a series of |
|
| 72:42 | P. S. P. That are strong enough to produce an |
|
| 72:45 | potential that then go on to the cell to cause any PSP and |
|
| 72:51 | All right. Now to answer the about what about my big toe? |
|
| 72:54 | , at the bottom of the of chain, what we hopefully have, |
|
| 72:59 | have a muscle cell that's going to to the neurotransmitter being released by that |
|
| 73:03 | is going to cause that cell to in the case of a muscle to |
|
| 73:09 | . All right So those are the simple steps. It's a little bit |
|
| 73:15 | than agent. Oh so three simple . I'll always find at least one |
|
| 73:24 | good. The rest you're going I know. Disney now. And so |
|
| 73:28 | just like pretending like you don't I don't know what that is. |
|
| 73:31 | home to your agent. Oh so . All right. I was I |
|
| 73:35 | the wrong direction. All right what we're looking at is we're looking |
|
| 73:39 | the process of diffusion diffusion. Remember an event that is very passive So |
|
| 73:45 | going to be a delay between releasing that neurotransmitter to stimulating. It's about |
|
| 73:50 | point five milliseconds. So it's very relative to us. But you can |
|
| 73:55 | if I have 123 cells in a then you can imagine there's a 0.3 |
|
| 74:01 | 3.3 over. Let's make our lives . 0.5 point 5.5 2nd delay. |
|
| 74:06 | from the first cell to the receiving it's going to take a little bit |
|
| 74:11 | time, 1.5 milliseconds for that process get all the way down to the |
|
| 74:15 | cell. So, complex pathways have synaptic delays. Simple pathways have smaller |
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| 74:25 | delays. So, you can imagine signals are going to have fewer neurons |
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| 74:31 | their pathways are going to have less pathways. Now if I've released neurotransmitter |
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| 74:41 | the synaptic cleft, it's going to a response to the cell. So |
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| 74:46 | don't want that response to occur for . I wanted to be a very |
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| 74:50 | short, very, very brief Right? I'm just sending something out |
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| 74:54 | I can get a quick response in next cell. So we have to |
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| 74:57 | through the process of termination. Now is gonna be true throughout the entire |
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| 75:01 | . Any process that you begin has have a mechanism in place to terminated |
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| 75:06 | . So everything you do is already turned off as you go along. |
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| 75:10 | right, But what we're looking at terms of the neurotransmitter, what's going |
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| 75:14 | to happen? Well, depending on type of cell you're looking and there's |
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| 75:18 | of different types of neurons. They different mechanisms. Good news. You |
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| 75:21 | have to know which one does, I just want you to know that |
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| 75:23 | are four mechanisms. Right? So is enzymatic destruction. You guys remember |
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| 75:29 | red rover, Did they allow you do that in in in grade |
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| 75:34 | I know that they're not letting you have recess recess anymore and stuff. |
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| 75:38 | don't know. You a little bit on that. All right. So |
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| 75:40 | those you don't know what red river . You get to walls of Children |
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| 75:43 | you say red rover, Red let billy come over and then Billy |
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| 75:47 | a leaping run as fast as you , charging at the other line to |
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| 75:51 | that line, as the other line Children desperately try to hold them |
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| 75:56 | And if you can get through that , you get to grab one of |
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| 75:58 | players and bring them over to your . All right. Enzymatic destruction is |
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| 76:04 | red rover. The difference is, that you have a bunch of enzymes |
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| 76:08 | are designed to chew up that neuro and so they're out there going Red |
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| 76:13 | . Red rover, let us you , Colin comb over the scene of |
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| 76:16 | comes out there like chip, chip chop chop chop chop chop |
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| 76:18 | And so they're basically chewing it up fast as as being released. |
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| 76:22 | that systematic destruction, diffusion. you know, if you don't hang |
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| 76:27 | Um at the synaptic Cleft, then not gonna do any good. So |
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| 76:31 | you just diffuse away and that's how get rid of neurotransmitter. 3rd is |
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| 76:36 | neuron itself can actually uptake. And you look at these pictures, these |
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| 76:38 | different types of neurons. You can here here here here here here they're |
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| 76:44 | taking up their own. So that's way it's like I'm going to release |
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| 76:47 | . I'm just gonna go ahead and it as quickly as I as I |
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| 76:50 | it to get it out of out of the snap to class. |
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| 76:53 | then up here, you can see is a picture of a bunch of |
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| 76:56 | and basically they're taking it up as . They don't respond to neuro |
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| 77:00 | they're just trying to remove it from cleft. And so in essence, |
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| 77:03 | have all these different mechanisms to ensure that neurotransmitter doesn't hang around too |
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| 77:07 | We're talking millisecond timing. So what neurotransmitters? And we're right down here |
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| 77:14 | the wire, aren't we? We've three minutes and I got three |
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| 77:17 | maybe two. You're gonna look at and you're going to say I there |
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| 77:21 | a whole bunch of things, I've to memorize. And really what I |
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| 77:24 | to point out here is that there a lot of different types of friends |
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| 77:27 | . There's about 100 different types. fall into a bunch of classes. |
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| 77:31 | classes are based on shape. I'm to point out the ones I think |
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| 77:35 | are important to you. That's what next slide really is. All |
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| 77:38 | But you can go through this list kind of say, oh yeah, |
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| 77:40 | there's peptides, there's fats, there's gases, nitric oxide, hydrogen |
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| 77:48 | you know, that's what makes eggs stinky. All right. These are |
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| 77:52 | ones you need to know. Sina . All right. You need to |
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| 77:55 | that one. That was the first discovered it's the one that uh acts |
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| 78:00 | the neuromuscular junction. It acts throughout body and other situations as well. |
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| 78:04 | , it can be excitatory inhibitory. was very excited when they discovered the |
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| 78:08 | neurotransmitter like who they must all be acetylcholine and they looked and looked and |
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| 78:12 | at nothing is like calling. It's only one in its class. So |
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| 78:18 | goes to show. So that's the one. All right. The second |
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| 78:21 | you should know is glutamate Gavin Ask irritates you can do. But |
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| 78:24 | notice I highlighted the three gs All . These are amino acids. You've |
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| 78:29 | amino acids are how you build They also serve as neurotransmitters. Specifically |
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| 78:35 | excitatory Gabba is a modification of Its inhibitory glazing is inhibitory. So |
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| 78:43 | of those three. And last thing the biogenic amines again, this is |
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| 78:47 | broader class. You can kind of over here. Here's a cata cola |
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| 78:50 | for example, you wanna hear that . It probably scares you because it's |
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| 78:53 | big scary word. But you already them, you know, epinephrine and |
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| 78:57 | or at least epinephrine, you goes by another name. Adrenaline guys |
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| 79:02 | of adrenaline. There it is. it right there, dopamine you've heard |
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| 79:07 | ? All right. These two are , big boys, but you've heard |
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| 79:11 | histamine? I'm sure you've heard of maybe. So, these are example |
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| 79:16 | biogenic amines. What you do is an amino acid cleave off one side |
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| 79:19 | it and make a modification That my one. No, I got one |
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| 79:25 | . I throw this up here because said 99.9% of all the synapses are |
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| 79:31 | synapses. All right. But there's small portion out there that are electrical |
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| 79:36 | . And I want you to see we're dealing with when we're dealing with |
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| 79:38 | electrical synapse. It is a cell has a gap junction with another |
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| 79:44 | So, what you're doing is you're the ions from one cell to the |
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| 79:47 | . So the action potential goes through of the individual cells. All |
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| 79:52 | There's different ways that it can but primarily you're gonna see these in |
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| 79:55 | and smooth muscles but they are also in the nervous system as well. |
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| 79:59 | , while when you think of a , think chemical understand that There are |
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| 80:04 | that are not that they are actually . Alright. And that's basically |
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| 80:09 | Next Tuesday. What would have that ? You have to come here? |
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| 80:15 | . Yeah, I don't have to up early and let's schedule my test |
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| 80:19 | . All right. Have a great . You too. Yes. |
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| 80:26 | deeply consider me a sort of review one was oh, it's gonna get |
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| 80:32 | faster. Mhm mm. Don't worry it. Don't freak out about |
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| 80:37 | It's all about organizing. You organize ideas, the information that you're |
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| 80:43 | Go from big to small. What's the big picture? What did |
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| 80:46 | learn today? And then you okay, I learned about, you |
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| 80:50 | , memory potentially learn about graded versus . Okay, what are the |
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| 80:54 | greater potential characteristics of an action And what you're gonna do is you're |
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| 80:57 | to find that your summary of If you work from big to small |
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| 81:01 | going to give you all the details ever know. All right. But |
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| 81:04 | you sit there and go, here's pages of slides, you're gonna panic |
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| 81:08 | your brain is going to say, don't want to do this and you're |
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| 81:11 | to freak out. You don't want freak out. Yeah, let me |
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| 81:16 | over here and save Because if I save, then you're all going to |
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| 81:20 | mad at me for not saving, |
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