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BIOL 2301 Human Anatomy & Physiology I - 2301_lecture12_1004
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00:06 Alright. You guys. So when guys read last night or whenever you
00:10 reading you you looked at this and , what the hell? Right.
00:14 can't even go where where did the go? We're now talking about some
00:19 physiology stuff. And the thing is that everything we're gonna do from here
00:24 out deals with electrical cells. All . So we're gonna be looking at
00:28 after the test, Look at muscles then we're gonna be dealing with the
00:32 system for the rest of the That's just the way MP one
00:36 And so really what we're doing now we're moving away from these macro structures
00:41 we need to understand how these cells . And so everything you're reading has
00:46 do with how neurons are working and ultimately how these muscle cells are going
00:51 be working. So, we're gonna to use our imagination for a lot
00:54 this stuff. Alright. That's just nature. And so when when approaching
00:59 stuff, I'm gonna try to give analogies that are gonna sound stupid part
01:04 that to help you understand it. , give you something stupid to
01:07 Right? And so our starting point kind of a review of things that
01:12 already learned. All right. So talked about cells, we talked about
01:15 plasma membrane and we said, plasma membranes are there to create a
01:21 that's unique for the inside of the relative to the outside of the cell
01:25 these membranes they are permissible or semi . They allow certain ions to come
01:31 and they allow certain ions to And the way that they do that
01:35 based on the number of receptors or that are located there. And whether
01:39 channels are open or closed. And so that's what this slide is
01:44 trying to remind you said look, just trying to remind you, we
01:48 these ions, the big ions that concerned with. These are there's like
01:51 master list and relates these top two are the most important. And it
01:55 look and again, you don't need memorize these numbers but over time you'll
01:59 seeing them over and over again. you kind of know like look,
02:02 lots of sodium on the outside of , very little sodium on the inside
02:04 cells there's lots of potassium on the cells, very little potassium on the
02:09 of the cells. And so whenever have any sort of imbalance those ions
02:14 to create balance, right? So I have lots of potassium on the
02:19 of sell it wants to flow out the cell and it wants to go
02:23 there to create equilibrium and the same for the sodium and if you look
02:27 calcium or chlorine or magnesium or any of these ions are going to
02:32 doing the same thing. All So that's what all this is basically
02:37 to tell you is look there's a when you deal with ions there's gonna
02:40 some sort of concentration gradient, that's big word, concentration gradient just means
02:45 a difference in the amount and when more more is gonna always want to
02:50 to where there's less. Now, other rule to that is that magnitude
02:54 . So if I have a little and less, then the flow from
03:00 little bit to the less is gonna a little more should be a little
03:05 a little more. The flow is be a little slow. Alright.
03:08 like getting on a skateboard, if on a on a slope that's really
03:12 skateboard, you scoot very, very . But if you get on a
03:15 that's like this. So, you think about in terms of concentration when
03:18 have lots of something and a little of something, I've got a massive
03:23 . So the speed at which I'm to travel between those two points is
03:26 , very quick. Alright, so matters. The second point we want
03:33 deal with here has to do with are we passing through? All
03:37 And so we talked about channels earlier we said, look, there's different
03:41 of channels. What they do is exist in one of two states.
03:45 gonna close state or an open If there if that gate, that
03:50 opens and closes, we call it gated channel. And so there's some
03:54 of modality. Something that causes that to open. And we also said
03:58 channels will always be open, their are never closed. Kind of like
04:03 door is never closed. And so is a leak channel. Alright,
04:08 they're constantly open Now a leak channel in case because you're gonna see this
04:12 just second is a type of voltage channel and that voltage is says the
04:19 around that channel are such to cause gate to open. And in this
04:23 of the leak channel, I'm not test you, I'm not gonna ask
04:26 what type of channel is, I'm letting you know. So a leak
04:29 , voltage gated channel where the the amount of voltage that causes the
04:33 shape is already present. So it in the open state. Kind of
04:37 this door wants to close but that bar up there at the top,
04:41 little swing bar that allows it to , its kind of in a stuck
04:45 , it's there, it's just set that way. So it doesn't ever
04:48 . All right now, the ability ions to pass through a channel is
04:55 to be a passive event and the is based on the physics, we
05:00 kind of described it said if you lots and you got little basically ions
05:05 gonna move down their concentration gradients. there's a rule or a physical law
05:11 that says, hey, we want reach equilibrium. So you don't need
05:15 pump things, things are just gonna go, The second thing is that
05:19 you're dealing with channels they're gonna be selective. Alright, that gate says
05:25 one type of bond can pass through . Some gates are a little less
05:30 . I mean you'll see things like example cat ion channels in the
05:34 you may come across those cat ion . Anything that allows a positive ion
05:38 pass through, typically potassium or Alright, but they basically have a
05:44 degree of selectivity and so once they're things will just pass through. So
05:52 I wanna go, I wanna get some specificity here. So to understand
05:56 cells, you need to understand that types of gates that are present and
06:01 number of gates that are present are are are important. So where you're
06:06 , you're gonna be asking kind of question, the two most important types
06:10 gates that we are going to be with are gonna be our, the
06:15 called ligand gated channel and the voltage channel. Now, as I
06:19 the voltage gated channel already basically it says look what is the charge around
06:24 channel. So you can see in little cartoon, what is trying to
06:26 is look this is what the charges now but when you change the difference
06:30 charge that also affects the shape of ion channel. So that ion channel
06:35 up and now you can allow for passage of materials. So when you
06:39 or see voltage gated channel think, , there is a charge. And
06:45 that charge changes it opens. All . The ligand gated channel is
06:51 much easier. Just says, there's a binding site for some sort
06:54 chemical, some sort of molecule. that molecule comes along, it binds
06:58 that channel and like a key into lock, it causes the channel to
07:03 up. All right. Now I these like little asides here because the
07:11 is is that we're giving you the version and I say kindergarten version as
07:16 for just for sodium as an there are hundreds of different voltage gated
07:25 . All right. And some of close when the membrane changes, some
07:30 them open. So, we're not about all that stuff. All
07:34 So, what I don't want you do is I don't want you to
07:36 fixed in your mind that there's one of channel. Alright, What I
07:40 you to understand is there is a , right? And so when someone
07:45 you something new and I guarantee in year or two years or four years
07:50 eight years, maybe 20 years into career, you're gonna learn something
07:53 And you're gonna go, whoa wait, wait, wait. That's
07:56 how I was taught it. All . So, I want you to
07:58 open to the idea that this is the limit. Okay. So,
08:04 if you understand the concept, I a key that opens up the channel
08:09 I have a change in membrane potential you're going what's membrane potential then that
08:15 what opens and closes these two types channels which are very, very common
08:19 the types of cells that we're looking Now. These statements I'm about to
08:28 are very important to just kind of and hold onto Alright. Numbers aren't
08:36 matter here. I don't care about numbers for you right now, if
08:39 if you're a biology major and you're through, you're gonna memorize those numbers
08:43 you'll see them all the time. what I want you to understand is
08:48 those ions are in the direction that flow. I guarantee. I'm gonna
08:52 you a question on the exam on . All right. So, if
08:55 don't know whenever you see a what that bracket represents is concentration and
09:00 this is saying, He says, , if you look at potassium
09:03 the concentration of potassium inside the cell greater than the concentration of potassium outside
09:08 cell. And if you already understand gradients which you kind of already do
09:12 we just said look more leads travels to where there's less than what we're
09:17 here. Is that potassium is more the inside the cell then that's on
09:19 outside of the cell. Ergo potassium out of the cell, Alright,
09:26 from the inside of the out. right. And this is true for
09:31 of the cells. All right. notice I didn't say 100% why?
09:36 there's always an exception. All Number two, sodium is the second
09:41 these two. These first two potassium are the two most important ones to
09:45 . Alright, when we're dealing with , we have more sodium on the
09:49 of cells than we have on the of cells. Therefore, sodium does
09:53 It moves into the cells. again, 99.9% of the time chlorine
10:00 weird. All right. Now, says that their chlorine is greater on
10:04 outside than than on the inside. , all things considered if you're just
10:09 at chlorine, chlorine would move from outside to the end. Right.
10:13 what's interesting is that it really And we're gonna see why in just
10:16 moment there's kind of an equilibrium balance already takes place. But if you're
10:23 looking at chlorine, chlorine wants to into a cell, okay. And
10:27 lastly calcium, calcium, there's more outside of cells than they are on
10:33 inside. So, therefore when calcium , calcium is going to move into
10:38 cell. Alright, these two You just flat out No, that should
10:45 one of those things where it's like taking my Oh, I'm taking my
10:51 know, whatever, m cat whatever I'm taking, this is something
10:55 take with me. Yes, All right, So we have lots
11:00 potassium on the inside of the south in fact, all right, so
11:04 instead of me just saying there's lots look at the number again, don't
11:08 the number. So here's inside, about 100 and 40 millimeter versus
11:12 Another moller. So the direction that's wants to go is from the inside
11:16 the cell to the outside the It wants to go down its concentration
11:21 . Alright. Yeah, pardon? , So chlorine is just very
11:30 That's why we used it in Um It's actually the chemistry of pools
11:35 is very interesting to have a pool I had to learn the chemistry.
11:38 like, man, there's so much this, not just just dump chlorine
11:41 there's phs and also yeah, So, okay, we can have
11:50 conversation later. Alright. Anyway, do we all understand concentrations were comfortable
11:58 that and that should be the easy . I think most of the
12:01 it kind of falls into these easy eventually, but if you've never experienced
12:05 stuff, it's gonna start sounding where something you already know opposites attract.
12:09 heard that. Right, So, I have a positive charge and negative
12:13 , they're attracted to each other, ? That's pretty simple and that's gonna
12:17 true for ions, Positive ions are be attracted to negative ions. All
12:22 . Now, if I take a bunch of positive ions over here and
12:26 very few positive ions over here, I have what is called an electrical
12:31 . Alright, now, if I a bunch of positive ions over
12:35 a bunch of negative ions over that's also an electrical gradient,
12:39 So you can just think about We don't we're not gonna bother thinking
12:42 negative ions. We're just gonna think terms of the presence of positive ions
12:47 mean they don't exist but a negative just the opposite of a positive.
12:51 , if I say I have lots positive over here, that means I
12:53 have lots of positives over there. , you see the difference.
12:57 So positive charges want to move down concentration grade there, electrical grades,
13:04 want to move and create equilibrium. , there's neutrality. Now, in
13:08 of charge, does that make Right? Yes or no. Makes
13:14 . No, it does not make . All right. So, if
13:17 know that positive negative charges are attracted each other, positive charges are also
13:22 by positive charges. Right. So do the positive charges want to go
13:26 there are no positive charges? if I have lots of positive charges
13:30 here and I have none over they're going to move until they can
13:36 as separated as they possibly can be we reach equilibrium. So, the
13:39 principles. Now, we're just looking charge. Now notice we're not asking
13:44 question, what is the ion? . So, if I have a
13:47 of sodium and a bunch of potassium here, those are all positively charged
13:52 . And what they're gonna try to is they're gonna try to separate and
13:55 equilibrium so that the positive charges are in both areas. That gonna make
14:02 ? It's kind of So, I it's early. I'm I'm struggling
14:05 All right. I got no sleep night and I have no idea
14:11 All right. So, ions are move towards areas of an opposite
14:17 The lack of a charge is very . Basically what you're doing is you're
14:20 yourself from positive charges. So, we have to ask the question
14:25 is that membrane permeable to that particular if it is? And we're gonna
14:30 those ions moving down those gradients. . And these are electrical gradients.
14:36 , So, it's the difference in number of opposite charges. See what
14:40 I have here. Oh, so say I have a membrane. I've
14:47 a membrane right here. I've got whole bunch of charges over here.
14:50 , you can imagine I've got a bunch of positive charges over here as
14:53 ions move. The difference in charge either side is also changing.
14:58 So, I'm just gonna make up have 10 ions over here. They're
15:01 positive charges have zero ions over So, it means I have a
15:06 10 charge over here. If one . What's my charge over here
15:10 Plus nine. What's it over Plus one. Right. And so
15:15 can see I now have a difference much smaller than it was previously.
15:19 , my gradient as ions move slowly down until you get to equilibrium.
15:25 of like the concentration. Every time have one over here move over
15:29 the concentration ticks down like. Alright, so, we have two
15:35 types of gradients that we're putting up . Are trying to deal with.
15:38 have an electrical gradient the charge and have a chemical gradient. Right?
15:44 at whichever ions are involved. And you look at the cell, this
15:48 kind of what it looks like. is not the entire sale notice.
15:51 only putting up here. Just a of different ions. Alright,
15:55 I want you to focus on the here. Alright, so, here
15:58 have these A's A's represent an ion our cellular proteins. All right there
16:05 ionic cellular proteins. An ionic. you're not sure what that means,
16:09 means negatively charged. Alright. And are positive charges, attracted negative
16:16 Yes, opposites attract. All And so, you can see over
16:20 we have a lot of potassium a of potassium inside the cells.
16:25 they're balanced a little bit by those charges of the cellular proteins similarly on
16:31 outside. We have lots of sodium we have more chlorine out there as
16:36 . You see your you can even we have the occasional potassium, so
16:39 can see the concentration gradient, we the occasional sodium so we can see
16:43 concentration gradient. But what we're seeing on the outside, there's a lot
16:47 sodium and it's balanced by the So positive negative charges are attracted to
16:51 other. But the thing is is there's not enough negative charge for every
16:58 charge on the outside and there's not negative charge. Or sorry, there's
17:01 enough positive charge for every negative charge the inside. Now help you understand
17:07 . I'm gonna use a dumb Ready for dumb examples, dumb examples
17:12 awesome. Alright now I know uh two places at least I know of
17:18 Houston that has two high schools next each other. A leaf has two
17:22 schools right side by side and then over in River oaks you have two
17:27 schools, there's Lamar and um ST sitting side by side and a
17:32 I can't remember which is Hastings and sick. Okay and I'm sure there's
17:36 in Houston because that's why we build in Houston. We've got lots of
17:40 . Let's just plop two schools down let them duke it out side by
17:44 . Alright, so can you picture two schools next to each other to
17:48 schools? All right. Now, want you to picture for a moment
17:51 these high schools there are couples that . Would you agree with that?
17:55 did people find find coupling? Ok. Now, for the purposes
18:00 this, I need you to think terms of opposites. Alright, So
18:05 bear with me on that. All . So, you can imagine in
18:08 high school, there are a whole of couples that have been formed in
18:11 high schools and they're separated basically by fence. Right? So, I
18:16 you to also imagine at lunchtime that goes and eats outside on campus.
18:22 right. So, you can imagine time you got your couples walking
18:27 But there's also some people that never up with an opposite. Right?
18:33 And they're sad about that, Because everybody wants an opposite. Not
18:40 , but just for the sake of this this example. Right? And
18:44 you can imagine um I'm gonna use . Okay, Okay. It's okay
18:50 L six gonna be on the other . So, over in Hastings,
18:53 got a whole bunch of couples and have a whole bunch of young men
18:58 are sad because they don't have a . Okay. And they're going to
19:02 and they're sitting there just kind of and moping around. Okay over at
19:06 sick we have all a bunch of , but we have a whole bunch
19:09 young women that are sad because they hooked up, they don't have a
19:13 . So they go out to lunch they're all sad and you got that
19:16 sitting in between them and when they up, because eventually you'll have to
19:20 up to see where you're going, look up and then across the
19:26 there's something I can couple up And so what do you do?
19:31 start moving towards the fence and you up to the fence and you sit
19:36 at the fence like this and they with the women, the young women
19:39 like, there's guys on the other and the guys are on the other
19:43 going women and they're on the other going, there's women and they're stuck
19:50 they can't get together, why can't get together? There's a fence in
19:54 way and that's what applies the membrane . So when you're talking about membrane
20:00 , Alright, you're wondering where was going with all this? What we're
20:03 about here are membranes and membrane Is there a potential for all those
20:09 individuals to get together? Yes. potential energy. If you've taken any
20:15 of physics, like if you took physical science in high school, If
20:19 taken physics, you know that when taking two things that are attracted to
20:23 other and pushing them apart. It's take effort. It takes energy
20:29 And that's what's going on is the membrane itself sits in between these two
20:34 that are trying to get together and they're trying to get together.
20:38 there's energy there that isn't happening But all we gotta do is allow
20:43 to get together and then that energy be used. You'll get kinetic energy
20:46 you can use that energy to do . All right, So, that's
20:51 of what's going on. Every cell your body is like this,
20:56 Every cell in your body has a bunch of potassium bound up to these
20:59 ox cellular proteins. But they there's negative charge inside the cells.
21:04 they are migrating to the membrane and of saying, look, I see
21:08 charge out there. How do I to that now, the an ox
21:11 your proteins can't leave. They're stuck too big. Right? And then
21:15 the outside of the cell you have and chlorine hooking up But you have
21:19 much sodium that it's like, I to find a negative, oh
21:22 there's a negative charge on the other of membrane. So, it crowds
21:25 that membrane says, how do I inside to that negative charge? And
21:30 that difference in charge between those positive sodium and those negative antibiotics cellular
21:37 Is that membrane potential. Now, I point out here is that the
21:42 themselves have no charge, right, membranes just in the way the charges
21:48 the ions on either side, and what you can see lined up in
21:51 picture right here. You can see sodium lined up here. You can
21:58 that charge lined up and all we do is figure out a way to
22:01 them together. So how do we ions together that are stuck on the
22:06 that memory those channels the proteins. right. We have to all we
22:11 do is open up some gates and can let that happen. All
22:15 Now, how do we measure all stuff? Because you're gonna see these
22:18 And when I sat in your it bothered me that the professor would
22:21 up here and talk would just sit and go and the membrane is binding
22:24 million volts. And then you start on and you'd be like, wait
22:27 second. Why are you throwing numbers me? And where do they come
22:30 now? Maybe you don't think like ? But you know, knowing half
22:33 something drives me bonkers, which is why I'm sitting up here at the
22:36 of the classroom. Right? I to find out all the answers.
22:40 don't know them all. But I to find them all out. All
22:43 . So, what we use we a volt meter. And the way
22:46 can think about this is we have probe inside the cell and we have
22:50 ground on the outside. So, we're doing is we're comparing the inside
22:55 to the outside and then what you is you look and see what does
22:58 charge difference look like? And it that the charge, if it's negative
23:02 that the inside of the cell has positive charge. I know that sounds
23:07 backwards to say it that way, that's kind of what we do is
23:09 look at the presence of positive So we say there is less positive
23:14 on the inside than on the So inside versus outside. And then
23:19 it's positive then we say there's more charge on the inside relative to the
23:25 . Okay, So notice we haven't anything about negative charges. We don't
23:29 about negative charge is kind of like , I thought that would. They're
23:34 least a couple of. You got . Alright, negative charges were just
23:38 of ignore. All right. the question is when we're using a
23:41 meter, we're asking the question, is it like? And you're looking
23:45 the probe? And so in this our probes are going into the cell
23:48 we're comparing it to the outside inside outside. So, typically what we're
23:53 is we're measuring in Miller volt this telling us the ability of the cell
23:56 do work. It's basically saying how potential energy is there? All
24:02 You're gonna see on the next two equations. Alright. The purpose of
24:06 you these equations is one because I there's a nerd in here. Who
24:09 to go do the math? At one. All right. The rest
24:12 us just like to avoid the All right. But I want you
24:16 show you that you don't have to math in this class. We're not
24:20 don't need to know the I you don't need to be able to
24:23 . I'm not gonna ask you to that. But what this can do
24:26 shows you very quickly. When you at an equation like this, you
24:29 do You can see a ratio there it's like, okay, what I'm
24:32 is comparing outside versus inside. That's it does. And that's why I'm
24:36 to show you the equation. so, the nurse equation, which
24:42 what this is right here, allows to look at a single ion and
24:47 the question where at what voltage is reached for this particular ion.
24:55 What? When when when when we balance between the concentration gradient and balance
25:02 the electrical gradient. Alright, the way you can think about
25:06 if I have a lot of ion here, That ion is gonna move
25:10 ? Remember what I said. if I let's just use sodium for
25:13 , if I have my membrane, have lots of 10 sodium over here
25:17 I have zero sodium over there every a sodium moves, that's moving down
25:22 concentration gradient until equilibrium is met, ? So, I'd be five.
25:27 ? But every time one of those ions moves, it's taking with it
25:32 charge, Right? And so there's to be at a point where the
25:38 of an ion is attracted back out . Right. In other words,
25:45 time an ion moves your content, basically moving a charge. And
25:50 remember opposites attract or opposites are trying or charges are trying to find
25:56 And so what you're doing is you're to figure out where is that balance
25:59 be when those two gradients which move opposite directions of each other, where
26:06 that balance gonna be where that ion there and goes, okay, I'm
26:09 go this way, No, I'm gonna go this way.
26:11 I'm gonna go this way. In words, it finds that point of
26:14 right? Where the seesaw no longer back and forth. That's what the
26:19 potential is. All right? for every eye on we have a
26:24 gradient and we have an electrical gradient move in opposite directions of each
26:28 The nursed equation allows us to find point where equilibrium is met for that
26:35 eye on All right? So all gotta do is just ask question,
26:38 is the concentration on the outside versus inside? What's the valence and then
26:42 can do a little math and it'll you that thing out. You don't
26:45 to do that. Alright, but if you wanted to you can
26:48 plug in these numbers, right? can say here's the outside, here's
26:51 inside throw into that equation. And should get that number right there.
26:55 right. So how many ions are play when you look at a
27:03 You got four going on. That's that's a good answer. If you
27:09 to say lots, that's a good . Right? We typically focus in
27:14 two. All right. But the is that you have that we don't
27:18 consider Right man, we got We got phosphates. We got all
27:22 of stuff. And so there's an uglier equation. Right, this
27:27 Right. Did I miss it? , there's apparently click through three slides
27:34 . Alright, this is it right . It's called the Goldman Hodgkins Cats
27:38 . Again, don't memorize it. don't memorize this. Okay, but
27:44 I want to show you is that considers all the different ions. And
27:46 this case we're looking at just three . But you can imagine you'd have
27:49 include zinc. You have to include and calcium, phosphate. Everything.
27:55 that's there. But what's interesting about equation and why I'm pointing out to
27:59 because it points out the other factor becomes very, very important in understanding
28:04 movement of ions. So let's go to our little example. We have
28:10 that membrane, we have those couples want to move through. We have
28:15 way to get them together. What we have to do? We have
28:17 open up a channel really, In case it would be a gate right
28:21 the fence. Alright, So they're move now. How many people can
28:25 through one of those gates at a do you think you think many?
28:30 , we'll go with I'm gonna I'm make this easy. We're gonna say
28:33 . All right. But let's say have 100 couples that want to
28:37 how long is it gonna take for to happen a long time.
28:40 if I want to increase the what do I need to do?
28:45 have more gates have more gates and those gates open up. In other
28:50 , in in biology. Parliaments what say is we need to increase the
28:56 . Soap permeability is an important factor it comes to the movement of ions
29:02 and forth across the membrane. It the rate at which things go.
29:06 that permeability also affects that membrane Okay, so for example, let's
29:14 here, um I think that's probably on this on the other slide
29:20 But what I want to point out is that when we're looking at
29:23 the things that we're going to consider most. They're gonna be sodium
29:27 We're gonna look at the an ox your protein. They're the ones that
29:30 the biggest role. And then chlorine a smaller part in trying to figure
29:35 what that membrane potential is gonna All right. And again, calculating
29:40 out. But this is kind of side. The permeability is where I
29:43 trying to go with this. All . So, this little line right
29:48 represents the membrane potential. That's what stands for. All right. And
29:52 I did the equilibrium potential for potassium sodium, I calculate it out using
29:57 nursed equation. The first one there my equilibrium potential way over there.
30:01 61. Alright, if I do membrane potential for potassium, you can
30:07 it's over here about minus 90. . And then chlorine sits there about
30:12 66. But if we went and the membrane potential for a cell using
30:20 equation right there, Then what we is that VM comes out to about
30:27 now, -70. Looking more like equilibrium potential than the other. Does
30:37 look more like sodium look more like potassium? All right. And
30:44 what it's saying is is that when make this calculation and based on permeability
30:50 that the equilibrium potential looks more like . And the reason it looks more
30:54 potassium because of that that permeability for versus potassium sodium. Alright. Ready
31:01 another dub example to help you understand . Ready? Alright, y'all been
31:05 a football game. All right, halftime. We're losing. Of
31:12 I'm so tired of this year Yeah. Last year was a lot
31:18 this year. I'm really not Okay? And I'm a big football
31:23 , not even just you. H I went to two lanes, so
31:25 kinda gotta I was over friday. anyway, halftime, everyone gets
31:33 goes to the restroom, guys, long I'm talking to the guys,
31:37 the ladies guys. How long did take you to go in and out
31:39 the restroom? Few seconds. I that answer ladies, when are you
31:45 back to your seats? 4th Right. Maybe if you're lucky you
31:52 you go out there during halftime and like there's never a line for the
31:56 restroom. Why? All right, , I'm gonna give away some
32:01 Alright? And the guys restrooms, speaking, we have troughs.
32:08 And so what that means is, when guys need to go to the
32:11 , these trials, normally, you , allow four people stand side by
32:14 . But you know, during halftime kind of ignore those rules and we
32:17 and we stand like eight deep at trough. You know, we just
32:20 of walk in there, look Don't make eye contact anybody do your
32:24 and you get out, ladies, have stalls you can't put more than
32:30 person in the stall, Right? can't do your business, like guys
32:35 do their business. And so you to wait till a stall becomes
32:40 And how many stalls are in a restroom? Maybe 20. So at
32:44 given time it takes 20 people can served. So, where a men's
32:49 can serve several 1000 in a Right, A woman's restroom, you're
32:55 there until after the game. So in biology parliaments, what would
33:02 say with regard to permeability when it to restrooms? Do men's restrooms have
33:08 or less permeability than women's restrooms? ? Okay, so, we understand
33:15 concept is that we're allowing more men move through the system. When we're
33:20 about the membrane, we're looking at channels. Alright, so we have
33:24 channels. We have sodium channels. . And at rest we're looking at
33:30 channels in particular. And so the is, is if the membrane potential
33:36 VM is -70. It basically I look more like the the equilibrium
33:43 for potassium. So, that means means there must be more potassium leak
33:51 , then there are sodium leak If the VM sat between the
33:57 some point, we basically say there's equal number of channels. And if
34:02 was way over here by the equilibrium of sodium, then we'd say that
34:06 potential that VM is a result of sodium leak channels then potassium like channel
34:16 you see what we've done here is , the relative number of channels becomes
34:21 . And if you look at that that I've circled up their box circle
34:26 I made The box I made basically that permeability. Now I hate that
34:31 did it this way because use they decimals and you should never use decimals
34:36 you're doing. I mean doing comparisons this, what this is basically saying
34:40 for everyone potassium leak channel there is . Now, if you do your
34:47 , that means there's 25. So every one sodium leak channel, there
34:53 25 potassium leak channels. It kind sounds like a men's and women's
34:59 For everyone stall in the women's There are 25 means to which men
35:08 use their restroom. That makes In other words, there is a
35:14 ability for sodium to leave the cell it is for sodium to get in
35:18 cell. That means for every one of task or of sodium going into
35:23 cell, 25 molecules of potassium And so that drags that membrane potential
35:31 over in this direction. And that's we have this -70. All
35:37 Now, at any given time, of these things are in play,
35:44 ? We have chlorine channels. We sodium channels. We have potassium
35:49 They're all linked channels, potassium is out leaving behind negative charges. So
35:56 attracted to the negative charge. Two ? What attracted to the negative charges
36:03 . Right? And sodium sits up in the picture? I'm not gonna
36:10 you something that's already there. potassium is leaving, right? So
36:15 time potassium leaves it leaves behind a charges, it attracted that negative
36:20 Yeah, but it's only gonna start back as if the inside of the
36:26 becomes -90 is gonna say wait a . That negative charges there is kind
36:32 attractive. I'm gonna go hang out it. But right now, the
36:36 gradient is driving the sodium away, the inside more and more negative.
36:42 right. So, that's why it's outward. It's moving towards that
36:47 But it doesn't quite get there. reason doesn't quite get there is because
36:52 have sodium leak channels. Now, there are more leak channels for potassium
36:57 there is for sodium. But there leak channels. So, those negative
37:02 on the inside are like really attractive that sodium. So, what does
37:07 sodium do? I want to go direction? How you doing negative
37:13 Right? We're back to the example the high schools, right? How
37:17 doing Right? It's attracted to the charge, positive charge. Doeses't care
37:23 that negative charges. It's just a charge. And so, it's moving
37:28 , but you can only move one for every 25 that are moving
37:32 And so the inside of the cell more negative and it draws sodium towards
37:37 and sodium wants to keep moving in it reaches its equilibrium. And where
37:41 its equilibrium At plus 61. So never ever slows down. It just
37:48 have many opportunities to go into the . Chlorine is attracted to positive
37:55 but it's also attracted to negative. mean, to not only potassium,
37:59 also attracted sodium so, some of chlorine is gonna move in, its
38:03 potential is about -66. So, already at equilibrium for the most
38:09 so it barely moves. It's like right, I'm kind of cool.
38:12 gonna wait. sodium went, let I'm gonna go with sodium now,
38:15 is kind of cool again. wait, potassium left. Okay,
38:18 me go back over here and it kind of sits there keeping balance around
38:24 minus 70. It doesn't move a . All right, but potassium is
38:32 and sodium is moving and every time of these things moves, there's a
38:38 called the sodium potassium 80 pes pump the expense of 1 80 P.
38:42 says, wait a second, I you on the inside of the
38:45 potassium you to go back over you three sodium is you go back
38:49 there and it puts them back where started and then it's like, oh
38:53 , I'm I still want to go inside and so everything is in constant
38:58 and that membrane is sitting around minus as a result of all of those
39:04 . So, there's a passivity, natural movement first, potassium move out
39:10 there's enough channels for it to So as it's trying to leave the
39:13 moving down its concentration gradient, trying get the good thing. I have
39:23 . Can't trust these things. There we go. It's on
39:48 All right, So what I was is that we have sodium wanting to
40:02 in, trying to reach its equilibrium . It will never reach it.
40:06 have potassium leaving, trying to reach equilibrium potential. It will never reach
40:11 . We have the sodium potassium a pump, making sure that they never
40:15 it and putting things back into motion that you're always replenishing the things that
40:20 been lost, right? And this what establishes that value, that
40:27 So, when you look at a and we ask, what's that membrane
40:30 , it's these factors that are taking all of this movement, it's not
40:36 sitting there going, not doing There's a lot of movement going
40:40 And if we want to make a be electrically active, what we're gonna
40:44 to do is we're gonna want to that permeability. And when we change
40:49 permeability for either potassium or change the for sodium that's gonna cause more ions
40:56 move. And when ions move, is electrical activity and you can use
41:02 activity to do stuff. And so is the baseline our understanding of how
41:09 cells do their job. So how and how muscles are gonna work.
41:15 gonna pause here. I saw one . Did I answer it? Or
41:19 I make you forget it? Any questions I know this stuff is
41:25 . This is why I try to those stupid examples. You're not gonna
41:28 the bathroom example, are you? not gonna forget the stupid high school
41:33 , are you? Well, he I don't know. Yes.
41:42 So, membrane potential just kind of generically to the imbalance of those,
41:49 resting membrane potential. And I should look at my slides more carefully.
41:53 what they're actually saying. Resting membrane refers to a cell at rest.
42:00 , what does a cell at It's a cell that's not doing its
42:04 that it was designed to do? , your muscle when it's not
42:08 has a resting membrane potential. Your when it's not releasing neurotransmitter has a
42:13 membrane potential. It's it's starting All right. And so, what
42:19 gonna do is we're gonna use that point to then cause the cell to
42:22 stuff. We're gonna change that membrane . Anyone else questions? Yes.
42:30 . So, the question is, the difference between the membrane potential and
42:35 equilibrium. So, when we look the equilibrium potential. So, what
42:39 saying is what is the point where particular ion. So just that one
42:45 on. So this is an experimental , it doesn't exist in reality because
42:50 you look in a normal cell, have to consider all the ions that
42:54 there. But if you could make cell and uh just put sodium on
42:59 outside or the inside, you and then ask the question, how
43:02 it move? Where does where does find its balance? You can then
43:07 that out. So that's what that to, is the point at which
43:10 particular ion finds its balance using the numbers in in the real cell.
43:20 else? I I understand this stuff be confusing. Alright. But remember
43:27 a stepping stone to understand greater stuff we're gonna come back, you're gonna
43:31 using it. And so as you it, it should make more and
43:35 sense. So if you're sitting there , I don't want to ask the
43:37 because it looks stupid and and I want to look stupid in a group
43:40 300 people. First off, you're gonna look stupid, but I guarantee
43:44 40% of you don't understand what the I'm talking about, right? See
43:49 some of you are not here. . Yeah. Alright. Yes.
43:56 Yes. Zero math today. What their numbers? Because I think sometimes
44:06 help you understand what you're doing physiologists love numbers. We're not we
44:14 not doing the numbers. If you at HCC I'm just gonna say if
44:20 at HCC they would make you do nerds equation. I know faculty over
44:24 , they'd make you do the math they're mean. I don't know why
44:31 reasons. Some anatomists think it's important you to do the math. I
44:34 think it's important for you to do . I think what helps you to
44:38 differences? Right differences are easier to when you see a number like 1
44:43 verses 10 or five or whatever the numbers were right versus big versus
44:49 What does big mean? What does mean? Right. And that's why
44:53 throw those up there. Right There's value for the membrane potential.
44:59 will see over and over again. is a measurable thing. Remember what
45:02 said, If I get a volt , shove it in the neuron and
45:06 measure the difference on the inside versus outside. You're gonna see that membrane
45:10 of minus 70. You look at cardiac muscle, you'll see a different
45:14 . You look at a skeletal you'll see a different number.
45:18 But the principle is still the right? It's basically looking at the
45:24 of ions from the inside versus the , which is based upon all those
45:30 channels. And you gotta gotta gotta , it's a good question.
45:38 you can choose it could be It could be the women. If
45:41 if potassium is the men, then you have to think of the
45:45 acceptable protein as the women. So positive charge versus negative charge. That's
45:50 attraction. Right? Traction. Doesn't what I on you are. As
45:55 as it knows your charge, Positive charges are attracted to negative
46:00 Or the other way. You can the positive charges are attracted to areas
46:03 there are no positive charges either Yeah. So I'd ask you for
46:16 , the question is what type of would you see for an equilibrium
46:20 How do you get it? How you get an equilibrium potential,
46:25 That's gotta know permeability. You gotta concentrations. Right? So, I
46:30 ask you the question of which direction the is the concentration gradient? Which
46:34 is is equilibrium potential? Right? , we know that or equally.
46:39 , the electrical gradient. So, know, for example, concentration gradients
46:43 opposed to electrical gradients. They move opposite directions of each other.
46:48 That's why I said the first time that first slide. So that's kind
46:52 what we're trying to go, is to deal with concepts ideas.
47:03 No, but we're going to So the question has to do with
47:06 actual potentials which are thursday's lecture. I don't want to jump the gun
47:12 start explaining those just yet. All . But I do want to start
47:17 about neurons. Yeah, I'm willing answer a question until you guys stop
47:21 them. But we still have you a question. You know? Just
47:27 to get that shirt where it No one else. Back in the
47:32 , falling asleep. All right. to a little bit of anatomy.
47:40 . We we we dipped ourselves into physiology kind of felt icky. All
47:47 . I saw that. I saw look. Alright. Alright. So
47:50 move back out. Alright, So are the cells that that we're gonna
47:55 focused on primarily in the nervous Alright, So, they're the functional
48:00 lack of a better term. so these are an excitable cells.
48:04 have some specific structure to them and function. Their job is to produce
48:11 in their membrane potential that result as distance signals between the cell body and
48:19 terminal end of the cell. So, an action potential is an
48:24 of the type of a long distance . So, there's an electrical potential
48:27 that travels along the length of that to cause the release of a
48:35 A chemical message that then is used communicate to the next cell. All
48:39 now to understand why this is neurons can be very, very
48:44 So, for example, you have neuron as I said, we'll leave
48:47 spinal cord travel the length of your down to the tip of your pinky
48:51 that you can wiggle it right? you might have a neuron that's down
48:55 the tip of your pinky and then up the length of your arm to
48:58 spinal cord so that can transmit sensory . So these are long cells,
49:04 all of them, there's tiny neurons your brain, but that's an example
49:09 how long they can be. And if you're trying to get your hand
49:13 move, it would be kind of to be able to get very very
49:16 signals to the muscles that cause that . Would you agree with that?
49:23 . So if a baseball is flying your face, do you want your
49:26 to take its sweet time? Think Well, you know, move your
49:30 and your hands like, okay, just waiting for the signal.
49:33 You want a fast one. Electrical is a method of very very quick
49:38 . All right. So what it's do is it's gonna initiate and then
49:42 an electrical signal along its length. it's responsible for receiving some sort of
49:48 , determining how to respond to that , usually through that form of that
49:53 potential. All right. So, already mentioned is going to conduct
49:58 long distance signaling. And this is gonna be possible because of the presence
50:04 these types of channels that we've already about. The presence of these leak
50:08 . These ligand gated channels and these gated channels. So where they're distributed
50:13 very very important. And there's also pumps in there to keep everything back
50:16 balance. Alright. And so where located, their relative concentrations become important
50:23 . The way they communicate between cells not electrically though. So, remember
50:28 electrical signal is across its length Between 99% of the time. It's gonna
50:35 a chemical message. It's like you notes in class. Right? What
50:40 doing is when you're talking to you are giving them a message and
50:45 what these cells are doing. The . The chemical is the message between
50:50 . The electrical signal is you writing note down, trying to get the
50:53 from your brain down into that piece paper. And that's kind of what's
50:57 on here is I'm sending it from Soma, that body all the way
51:01 the length these cells you're born For the most part you do produce
51:06 neurons over the course of your but not very many. This word
51:10 here is a myth topic. you know what my topic means?
51:13 uses mitosis. Amy topic means I use mitosis. Alright, So once
51:19 create these cells, they don't continue divide and multiply for the most
51:24 you basically get what you get. right. They're also highly metabolic.
51:29 constantly producing these electrical signals and moving . So they need a steady supply
51:35 energy to do so. So that they're gonna be needing glucose and
51:40 And I'm being very generic here When say glucose because it's not actually
51:44 But I don't want to get into today. Alright. So when scientists
51:51 started looking at the at the they were specialists. And so they
51:56 everything special names. So they have the parts that you've already learned.
52:00 they have special names to them. is really frustrating. That means you
52:04 learn them. All right. So cytoplasm is called the carry on.
52:08 , I don't call it the I don't know. They just that's
52:12 how it is. They were They mean and cruel and I don't
52:16 All right. The ribosomes stained There was the specific staining mechanism.
52:24 the person who discovered it got its put on it. So the ribosomes
52:28 called missile bodies. All right. you look at this, this body
52:35 here, the cell body can be a soma. Right? And these
52:42 are referred to as dendrites. there's a distinction. Any extension off
52:48 cell body is a dendrite, but ones that receive maintain the name
52:54 The one extension that sins which is bigger and longer is called the
53:01 And so here you can see dendrite dendrite dendrite dendrite and then this right
53:06 is an axon. Now if you a bunch of these neurons and you
53:12 them together so that you have a bunch of cell bodies together in the
53:16 nervous system. We give them a name. We call them that that
53:19 cluster a nuclei. Alright. It's nucleus but plural would be nuclei if
53:26 see the same sort of clustering inside peripheral nervous system and I should back
53:32 . Your central nervous system is your and your spinal cord, peripheral nervous
53:35 is everything else. So in the nervous system those clusters of cell bodies
53:42 called ganglia. Alright, so there's specific terminology we use when these axons
53:56 and travel together as a cluster. we do is we're forming in the
54:00 nervous system, we call those But if we're out in the peripheral
54:05 system, we call those the axons together, we call those nerves.
54:11 this is gonna sound like a trick on exam. Does the central nervous
54:15 have nerves within it? And the is no. All right, because
54:21 terminology is specific to the peripheral nervous ? All right, that's the question
54:29 might see. Not necessarily on my , but you'll see it someplace.
54:34 . Central nervous system doesn't contain nerves contains tracks. So, dendrites are
54:40 receptive extensions from the cell body. ? They receive input. They respond
54:47 some sort of stimulus. Alright, it doesn't matter if you're on the
54:52 , if you're receiving, If you're poked by a needle, that information
54:55 picked up by a dendrite and that is being sent to the central nervous
55:01 via an axon axon are sending information right to receive information. Alright,
55:09 , in the central nervous system, is what this kinda looks like.
55:12 receiving information up here at the dendrites the axon sends that information down.
55:19 within the dendrites, we're gonna learn these two different types of membrane potential
55:24 . One is called the greater potential called an action potential. Graded potentials
55:28 going to be formed out here at dendrites and it's the uh if you
55:35 greater potentials and they get strong enough reach a threshold that's gonna cause the
55:40 of an action potential. Action potentials formed right here in this structure called
55:45 axon hillock. It's the base, foot of that axon. And so
55:51 you can get great potential strong enough cause that area to reach threshold,
55:55 get an action potential that then travels the length of that axon. All
56:02 , So, they use action These use graded potentials. Now,
56:07 axon can divide, it doesn't show in this picture, but you can
56:11 as you're going along, I can up here and go someplace else.
56:14 , I have two branches, those are referred to as collaterals, but
56:19 at the very end of one of collaterals, that's where you're gonna see
56:22 endings of the axon, This is the terminal, another name, you'll
56:29 might be Teledyne Andrea alright, so can see danger or dendrites comes from
56:36 word that means branch. So the dri a are gonna be found here
56:41 the terminal end. So, these right here, those are Teledyne
56:46 And then at the very very tip it kind of looks like a little
56:49 alien sucker finger, right? That , that little that little knob or
56:56 . That's the axon terminal. Or can be referred to as the synaptic
57:01 . And this is where the synapse going to be found. So,
57:08 axon is the conducting region. As said, this doesn't have all the
57:12 that you're going to find in the . You won't find missile bodies
57:15 you won't find the Golgi apparatus. , all the machinery to make proteins
57:21 to do all the hard and heavy of the cell are found in the
57:27 . In the para carrion of the . So, what you're gonna find
57:33 is basically gonna be cytoplasm and we it a special name because it's in
57:37 axon, it's called the axa All right. And then the plasma
57:44 of the axon would give it a name. We call it the axle
57:48 . To the plasma lemma again, neurologists neurobiologists think they're special. They
57:55 to name things especially. So everything being made inside the selma, you're
58:05 information from your dendrites. You're sending from the synaptic knobs in order for
58:11 to release neurotransmitter? You need to neurotransmitter. So you're making a neurotransmitter
58:16 the summer and it needs to be down to, that acts on
58:22 And then when you're done with making or maybe your recycling materials, you
58:26 to send information back to the summer it can be processed. So you
58:30 to have a mechanism to move things that very, very far and back
58:34 the cell body. And this is neuronal transport is. And there's two
58:39 and taro grade, that would be from the body. Retrograde. That's
58:43 the body when something is retro, does that mean? Old or from
58:51 past? Right, so it's in opposite direction, which you're going.
58:56 way does time go forward? so retro is backwards. Right,
59:02 that's just when you look at those , that's all it means. So
59:04 anterograde retrograde would be back. There's basic speeds. We have fast and
59:11 . So two gears I guess We move about 400 per day.
59:16 far is 400? 10 is a 100 centimeters would be a meter.
59:27 ? So 100 centimeters is 1000 So half a meter is how far
59:37 can travel in a day using So how big is that? How
59:42 is the meter? About three I don't know guys are terrible at
59:50 out lengths. Thank you. So about three ft. So half
59:59 How's that that work? Half a . Yeah. So, how do
60:12 do this? Well, we have in place. All right.
60:15 this is gonna be in both What we're gonna do is we're gonna
60:17 the transport proteins. Remember those connections dining to basically grab the vesicles,
60:22 will be full of neurotransmitter. What you gonna do? You're walking it
60:25 intermediate filaments down to the terminal in you start the vesicles. They're waiting
60:30 a signal to release the neurotransmitter in of slow axle. We're now talking
60:35 millimeters per day. So, this more like getting in an inner
60:41 you know, getting on a slow with your cooler of beer or your
60:46 claw, whatever. Alright, and sitting there and just let the current
60:50 you. So, it's just yep, I'll get there when I
60:53 there. That's what slow is this only interior. Great. So in
60:57 direction. Alright. So usually what gonna do is we're gonna use energy
61:03 the form of a TP to move things in the direction they need to
61:12 . All right, vocabulary words and becomes important because we're gonna use these
61:19 all the time and I need you them. All right. Flash back
61:24 3rd grade when we're doing number. . Remember number. Lines.
61:29 lines, people in middle number. . Okay. All right. So
61:33 remember the number line first time you negative positive numbers. If you're at
61:38 . Alright. You lack polarity or . You're zero. Right? Anytime
61:43 move in either direction along that number , you're you're creating polarity. Does
61:51 make sense? So if I'm at , I have no polarity. I'm
61:55 positive and another negative. Right? if I move even this far off
62:00 , I'm no longer zero. I now polar. Alright. So,
62:05 gonna use big numbers here. If I'm at zero here and I
62:09 , let's see. This would be for you. So, if I
62:12 over here 10 spaces now I'm negative . Right? So, what I've
62:17 is I've polarized. If I'm over starting at zero and I move 10
62:24 . This way I'm now positive I'm still polar, aren't I?
62:30 . Now I'm gonna come over here I have more space. So here
62:34 am at -10. Alright, which ? zero. Right over there?
62:40 minus infinity, isn't it? So if I move towards minus
62:45 have I become more or less More polar? That's called hyper
62:53 All right. If I move back -10, I've returned back to my
63:01 original polar position. I've re If I move towards zero, have
63:09 become more or less polar. Less . So I have deep polarized.
63:18 . So if I'm at zero I'm polar. If I'm off zero I
63:25 polarized right over here polarized. If become more polar hyper polarized if I
63:35 less polar D polarized if I go polarized and then I return that return
63:41 is re polarization. And that's what terms are. Now notice in our
63:47 graph up here, what we're using we're using a cell that has a
63:50 membrane potential of minus 70. And what it's trying to show you is
63:54 as I move away from my polarized . So at rest I'm already polarized
63:58 minus 70. So as I move from my polarized state towards zero I'm
64:04 polarizing. If I'm moving away from D polarized state away from zero,
64:10 hyper polarizing. So this right here that right there would be this line
64:16 from my deep polarized state back to original polarized date would be re
64:23 And same here. I mean my polarized state back to my original polarized
64:27 . That's re polarization. If I you this graph and flipped it upside
64:34 , it was plus 70. The rules apply as long as I'm moving
64:38 zero. I'm becoming less polarized. long as I'm moving further away from
64:43 , I'm becoming hyper polarized. The exception to this rule is this If
64:47 am deep polarizing and I passed zero I keep going. In other words
64:52 one movement I just keep the first that I used. Deep polarization.
64:56 don't go, oh, I'm now something because that just gets confusing.
65:01 you start. All right. We're see a little bit later. When
65:04 talk about actually, we started We de polarize and we cross over
65:09 and we go to plus 30. , that would still be deep
65:13 Alright. But that's we'll get there we get there. All right,
65:18 , the membrane potential changes. Any in that memory potential is what we're
65:23 use as electrical signaling in the We have two different types.
65:27 anything that changes the membrane permeability, that alters yuan concentration are is going
65:33 result in a membrane potential change. , if I dump sodium, you
65:37 do this. This this doesn't happen real. But if I dumped more
65:40 into your body, that could change potentials because now you've created an
65:46 Right? So, those values the I told you don't memorize the $150
65:51 versus 30 millimeter and stuff. Those are more or less constant in the
65:57 , but I'm not asking to memorize because it's okay, we don't need
66:01 know. All right. So, types of membrane potential change. We
66:05 great potentials graded potentials are short distance . That's what we're gonna finish up
66:12 today. And then we're gonna come and we're gonna deal with action potentials
66:15 thursday. Alright. So here we . We're looking at a cell,
66:20 can see there is the uh Selma a dendrite. Dendrite. Dendrite.
66:25 on. All right. And what a greater potential is a small
66:30 change. Alright. Of varying meaning it can be any size.
66:35 that size is gonna be the result the magnitude of the stimulus that you're
66:40 . So the bigger the magnitude of stimulus, the bigger the greater
66:45 the longer the stimulus, the longer potential. So there's a direct correlation
66:53 duration and magnitude when it comes to potentials. But these are very,
66:58 short, very small distance uh changes the membrane potential. So, what
67:04 is trying to show you in this picture here is that we're opening up
67:09 gated channel. Alright. In this case, it's a ligand gated
67:14 And when I open up that leg gave the channel, remember we have
67:16 those ions end up. They want go in, don't they?
67:20 I got their hands on this side the membrane, got the islands on
67:22 side of the membrane, they want get together, all we gotta do
67:24 open up the gate, this is . Opening up the gate. And
67:27 ions flow in and when that first flows in, it's gonna find its
67:32 and when I find my partner, removed that difference in charge. That
67:38 sense for every positive finds a I've removed a charge for every uncoupled
67:43 . The charge exists because that charge the lack of coupling. And so
67:50 can see at the point where the is, right, that's where we're
67:55 see the largest membrane difference. And as we move further and further
68:01 we're gonna see less and less charge change. All right, So,
68:06 this is showing you is the degree flow islands are rushing in tons of
68:10 on the front end and then their up. And only a couple of
68:13 are trickling out towards the edges so less flow. So a greater potential
68:18 be a deep polarization as ions floating sodium or it can as more potassium
68:28 out. But it's just a matter the flow. That's what you're looking
68:33 . What How much is moving, is the flux that's taking place?
68:38 here we have a high flux, that high flux is just steaks coming
68:43 . And then as you couple that ion is not gonna be traveling
68:47 further. Now, if you want picture this, You ever thrown rocks
68:55 ponds, swimming pools. People's don't think about the windows think about
69:01 pond's nice still pond. There's something picking up a rock and throwing a
69:07 into a still pond to disturb doesn't it? All right. So
69:11 an infinitely large pond and I take little tiny pebble and I toss it
69:16 the pond, right? To make little thing. You'll see a little
69:21 . The splash will be kind of , it won't it? But then
69:25 get a ripple and that ripple moves from the site where that rock went
69:31 , where that rock went, the is bigger, right? But as
69:35 travels away further and further and that ripple gets smaller and smaller until
69:39 dies away. Right? With an sized thing you're gonna see, it
69:43 dies off. Most ponds are too and it keeps going right that.
69:48 you envision that? Okay, picture a big rock 20 pounder right
69:53 that big 20 pounder in there, get a bigger splash. So magnitude
69:57 right? You're gonna get a bigger . That big ripple will start off
70:02 . But as it travels further and away from the site of the
70:05 it gets smaller and smaller and You just envision greater potential is the
70:10 is that you're not talking about rocks waves of water. What you're talking
70:14 is a wave of electrical activity. ? So, basically what you're doing
70:19 you're opening up a channel ions flow . And you're saying how much how
70:23 ions are flowing in at the site stimulation? Lots, as you move
70:27 away, how many ions are moving and less and less and less and
70:31 . And the reason is because along way those ions are finding their partner
70:36 they don't need to move any Okay, so this is a very
70:42 small region just like that little splash it just occurs along that short
70:51 So I've already mentioned this, this just showing you size and duration.
70:54 if you need to go back and at that, so bigger membrane potential
70:59 a result of larger stimuli. They they don't show you here is one
71:03 going longer like this. Then you'd one that goes up and longer like
71:08 . All right. So there's some about greater potentials. 1st they decrease
71:15 the intensity of the distance traveled, we've already seen. All right.
71:20 The potential themselves are short lived so don't last forever, basically, they're
71:25 there for that short period of time you get the stimulation. And when
71:28 stimulation dies away, the greater potential as well. So, what this
71:36 trying to show you is that here doing stimulation notice I can go in
71:41 directions. It's just like that When I throw that rock in the
71:45 , the ripple doesn't just come towards . It goes in a circle away
71:48 that site and that's kind of what saying here, look, I'm getting
71:51 stimulation there. So I get this deep polarization, but as I travel
71:56 and further away that deep polarization. I was measuring it at this point
72:00 this point is much much smaller and , the reason for that is because
72:04 ions found a partner and they don't to travel any further. And what
72:10 want to do with the greater potential wanted to get to this point.
72:14 wanted to to arrive there to create stimulus that we need to initiate an
72:19 potential. Now we have names for greater potentials and they're usually abbreviations and
72:27 just make our lives easier. So first type is an excitatory potential.
72:34 . And so remember I am receiving . So what I'm looking at is
72:41 looking in the receiving cell. So you see this term you're in the
72:47 cell, the term is excitatory post potential or E. P.
72:52 P. So it just tells you name it's excitatory. The interaction between
72:57 neurons is called the synapse. So the receiving cell that's on the post
73:02 side and this is the membrane That's why you have potential.
73:07 So here the neurotransmitters being released. is the post synaptic cell and the
73:13 of that neurotransmitters causing the opening of . These are ligand gated channels that
73:19 sodium to rush into the cell. sodium moves into the cell, the
73:23 of the cell becomes more positive. if our cells started off here at
73:28 and I'm becoming more positive because sodium rushing in positive items are coming
73:33 That means I'm moving in this direction means I'm becoming less negative which means
73:38 am de polarizing. So when you the word excitation, you should automatically
73:45 deep polarization. Those two words go hand in hand. All right.
73:50 so this is what it looks like a graph. Right here, you're
73:52 rest, you are deep polarizing. as we saw in this picture over
73:58 , as you move towards the axon , the strength of that signal gets
74:03 and weaker and weaker. So what want is you want to have really
74:06 strong ones. The I. S. P. Is just the
74:09 . See inhibitory post synaptic potential. I am again, I'm on the
74:13 synaptic cell my membrane potential that minus I open up voltage. Sorry,
74:18 gated channels. What's gonna happen is potassium is gonna move out or if
74:23 a chlorine channel, chlorine will move . Alright. And when that happens
74:29 become more negative. Right Leave. moving towards minus an I.
74:36 So what if I if I move direction, what have I done?
74:39 hyper polarized so inhibition or I PS inhibition results in hyper polarization. I
74:46 further away from threshold. And so is what it would look like on
74:50 graph. And just as before the away from the side of excite,
74:55 less membrane potential change you're gonna So it just diminishes over distance
75:04 E. P. S. S. And I. P.
75:05 . P. S. Don't work themselves. They're not particularly strong.
75:10 right. Instead what we have is look at the sum of all the
75:15 PS. And PS PS. That occurring on an individual self. So
75:18 , right here is what a neuron kind of looks like. Right?
75:22 can see there's thousands of interactions between soma and other neurons. Each of
75:28 uh ends representing a synaptic knob. of those knobs are releasing an inhibitory
75:35 , some of our releasing excitatory And so some cells are telling that
75:42 I want you to become excited? of them are telling them I want
75:44 to not become excited. And so we're doing is we're measuring the different
75:50 and inhibition. We're adding things Think of it like a pole,
75:55 ? Have you ever done a poll your friends whether or not you should
75:58 up with that person. Have you that right? It's just like I
76:02 make decisions for myself. So, want you to make it for
76:04 So maybe you go onto your favorite media site and ask your 4000
76:08 right? Say, hey, what I do? Right. And so
76:12 are they gonna do? Some people gonna tell you break up somewhere,
76:16 can say no, no give them chance. And then what you're gonna
76:20 based on that poll is you're going become you'll be broken up or you're
76:25 be staying together and that's kind of these are doing and this this addition
76:30 summation of cells or of signals of P. S. P. S
76:34 I ps ps collectively are referred to the G P. S.
76:38 The grand post synaptic potential. I you guys are excited to get out
76:43 here but we got three more four More minutes. Hey, I
76:49 my clock. All right, so do we get there? How do
76:55 make a G. P. P. Well, it's through this
76:57 of temporal and spatial summation. When see the word temporal, what do
77:01 think of? Thank you when you of space or spatial space?
77:07 here's our last little slide and you go home, go to your next
77:11 , go learn your english which is useless by the way. Never use
77:15 ever again. Alright, spatial summation is when you have two different inputs
77:24 at the same time. Alright, I'm just gonna prove this, we're
77:28 come out here because you guys look you want to play more?
77:30 listen to me clap. Right, me if this is loud, loud
77:36 the two of us clap. is that louder? How about the
77:40 of us? 123? That We did. We added these up
77:44 we? That is spatial summation. three of us acting together creates a
77:49 signal that is all gps P. Tory post synaptic potential plus an excitatory
77:55 synaptic potential plus another excitatory post synaptic , creating a large G.
78:00 S. P. Now we can't you the example what happens when we
78:04 two E. P. S. . S in an I.
78:06 S. P. Because I don't how you do a negative clap.
78:08 just not possible. Alright, so would be spatial temporal. And there
78:13 there is the example of spatial, in the second one so you can
78:16 12 but the two together getting high to reach threshold. Our temporal summation
78:22 when one neuron or one input fires greater frequency. So me clapping creates
78:31 . You can see the space in the collapse. Now, I cannot
78:34 fast enough but just pretend I can't . There's a point where the sound
78:44 the next sound, right? And that's the same thing is going when
78:48 dealing with temporal summation where the signals coming so fast that you never allow
78:52 cell to come back down to And so what you do is you
78:55 building on top of itself and that's it's trying to show you here cancelation
79:00 simply where you take any PSP and I. P. S.
79:02 And you add them together plus five negative five equals great. That's easy
79:08 . All right. But remember you different magnitudes. So, if you
79:10 plus 10 and minus seven, you're have plus three. So when you're
79:17 with cancelation, you're removing magnitude. doesn't necessarily you're not necessarily coming back
79:23 zero. I mean, you might like plus five and negative 10,
79:26 you're seeing more inhibition. But all of these are means by which we're
79:32 to trigger a sell to fire an potential. When we come back on
79:39 , we're gonna deal with the action
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