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BIOL 2301 Human Anatomy & Physiology I - 2301_lecture21_1116
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00:00 Okay um sorry we're going to continue we left off, We were talking
00:07 the eyes and how they work and looking at the we start off with
00:10 at the different parts of the right. And so we're just kind
00:13 walking through the different types of cell . We last talked about the rods
00:17 the cones. Those were the photo cells. We're kind of laying out
00:22 they did and what we're doing now we're kind of jumping into, we're
00:26 off what those those characteristics are and you see here is gonna be repeated
00:31 little bit later. All right, I'm going to introduce this idea now
00:35 then we're going to come back to again and then we're gonna look at
00:37 bipolar cells, we're going to look the ganglion cells, we're going to
00:40 of put that pattern or that that together. And then what we're gonna
00:44 is we're going to move into how eyes actually work. We're gonna look
00:49 the molecular biology of that, which kind of scary sounding like molecular biology
00:54 it was actually one of the very systems that looked at signal transaction.
00:59 they name things pretty much for what did. And so it's kind of
01:02 , okay, here's this this this just gonna look at how the eye
01:05 and then from there we're going to jump to the ear and we look
01:09 structures are there and we're gonna ask question how do the ears here and
01:13 thursday we're going to do how to ears deal with the question of balance
01:16 equilibrium and then yada yada yada So I'm just kind of painting a
01:21 here. And so what we're we're talking about this question of rods
01:25 cones and their differences and similarities and really kind of like, well there's
01:29 lot of differences here, and this one of them, there is something
01:31 dark adaptation and basically what dark adaptation is it talks about how quickly the
01:38 versus the cone responds to light and respond very, very quickly, you
01:43 get a photon of light and they become 100% active. So that really
01:47 you it doesn't take a lot of energy to turn them on cones,
01:51 the other hand, take their sweet . You have to add a lot
01:53 light energy before they become active. what we have here then is we
01:57 two types of vision and all these are really not easy to understand.
02:01 have to kind of dig into it a while, but basically what it
02:04 is look, you know, if , if you start in perfect darkness
02:08 then you start adding a little bit light, you can start seeing a
02:12 bit, you can start seeing but you can't really discern colors all
02:15 much. All right, and what talking about here is what is called
02:18 topic vision and no picture is going demonstrate this. But I tried
02:24 So like over here, this would like if it was low light and
02:27 kind of see, you can kind see the shapes of the cars,
02:29 really tell their colors, but you tell where the curb is and so
02:32 so forth. But then as you more and more light, what happens
02:36 the cones start getting involved and you bleaching out. That's the term we
02:40 bleaching out the rods. And so rods become less important in discerning what
02:44 environment looks like. And now the are playing the major role. And
02:49 , that's what the picture on the looks like. Like, oh
02:51 I can see the cars, I see the color, there's a lot
02:53 light. My rods aren't doing so work now the cones have taken over
02:57 so dark adaptation deals with this question which type of vision are we using
03:04 the dark? We're using rods. the term dark adaptation in the in
03:09 light and the sunlight. We're using codes. All right. And I'm
03:12 come back and probably do the talk same way, but I don't know
03:16 you guys ever watch mythbusters, There's six people here and he was like
03:20 right, a couple years ago and can go and try to find it
03:23 . I think it was like So like nine years ago they had
03:26 show on. Why did pirates wear patches? All right. Now we
03:32 don't know. It's like basically some drew a pirate with an eye
03:36 And so now pirates have eye patches really the answer. All right.
03:39 lose an eye, you wore an patch, but not all pirates war
03:42 , uh, lost their eyes. so the question was, was,
03:46 did why do we always characterize And it has to do with this
03:51 adaptation? All right. You're fighting deck and then you're fighting down in
03:56 dark. And what happens is when are turned off, it takes them
04:01 long time for them to turn back again. And so what we have
04:05 a and we're gonna talk about that . And so what happens you go
04:09 from a bright area into a dark . It's really hard to see
04:12 We noticed that it's like if you from outside of the theater and go
04:16 the theater, it takes a while your eyes to start being able to
04:19 what's in that dark theater. All . But the opposite is not
04:24 right? You go from a dark , go to light areas bright and
04:26 all of a sudden you can start , you know what I mean?
04:30 done this, right? Got to into the mountains. That's a day
04:35 . All right. Yeah. It's what we go to the movies during
04:39 day when it's cheaper. All So, at mythbusters, what they
04:43 is they wore the patch so that could cover and protect one eye from
04:47 light. And so when they were downstairs to get the booty or to
04:50 , what they would do is they lose their vision in the eye that
04:54 light adapted. Then you just flip the eye patch and now you have
04:58 eye that can see in the dark they wouldn't try to prove this and
05:01 actually worked. But it's like Dude really do this. Probably not think
05:07 just fun story. All right. , sorry, the bipolar cell,
05:17 , what I'm going to show you is gonna be a little bit more
05:20 than what I teach my human fist . All right. But that's because
05:24 , your book talks about that and I want to just kind of address
05:27 . So, when you're thinking about organization, you think of the photo
05:30 cell is going to then stimulate the cells and for bipolar cells, they're
05:36 to be kind of the same They're very small cells. So they
05:39 graded potentials. And what they do they work in what is called an
05:43 or off pathway. And what that means is I have a photo receptor
05:48 and associated with it are two bipolar . One that's turned on when the
05:55 receptor cells turned on and one that's off when the photo receptor cells turned
06:00 , right? So you can think this when the photo receptor cell isn't
06:04 , the off pathway cell is the on pathway is not. And
06:08 when this cell phone reception gets the on pathway gets turned off on
06:14 this one gets turned off. And really what you're doing is you're telling
06:18 next step on the road the ganglion is am I being stimulated with light
06:22 not? That's really what's going on and why? Why we talk about
06:27 is because this is the first level processing that takes place in the eye
06:32 we can do greater contrast. And you can think about an object in
06:37 D. Like think about like a or a picture of an apple.
06:41 know, you have that light shining the part that's nearest to you,
06:45 ? And so you can kind of it's three dimensional shape. Kind of
06:48 I'm talking about here, right? what's happening here is light, light
06:52 hitting it in kind of a unique . And so there's areas that when
06:57 looking at it are going to be on pathways and the areas that are
07:00 of on the edge are stimulating the pathways. And so that's why you
07:04 this sense of three dimensions, not because of our binocular vision, but
07:09 of the way the eyes process Alright, but the idea here is
07:13 I want you to take away from . Is that downstream of photo receptor
07:17 we have the bipolar cell. The cell is doing the first level of
07:23 . Okay, now we're going to back to this idea of on and
07:27 in a couple of slides and I deal with it again. All right
07:33 , we've said in that neural we have the photo receptor cells,
07:36 have the bipolar cell, then we the ganglion cell, then the
07:39 the immigrant cells in between. We're of ignoring the horizontal and the
07:43 So, what I want you to about his photo receptor bipolar ganglion
07:47 ganglion cell goes off into the nervous . All right. The receptive field
07:52 not the photo receptor cell. The receptive field is represented by the
07:58 cell that's downstream three cells away. . And what we're looking at here
08:04 we're asking the question all right, that one ganglion cell, which cell
08:09 cells need to be stimulated in order stimulate that ganglion cell. So,
08:14 I want you to think about here that the organization is simply there's lots
08:19 photo receptor cells and then they begin fewer cells on the bipolar cells which
08:26 converge on the ganglion cells. when you some numbers here, we
08:30 use that picture right there on the hand side, You can think about
08:33 this. I have 100 photo receptor that converge on 10 bipolar cells which
08:41 converge on one receptor cells or excuse , one ganglion cells. All
08:45 so you can think about it. I have those 100 cells which are
08:50 here didn't draw if I stimulate this or stimulate that sell, it doesn't
08:54 . I'm going to stimulate that gangling . Right? If I stimulate this
08:58 or this rod, I'm going to that. So, the idea here
09:02 that there's a bunch of cells that up the volume and it doesn't matter
09:07 within that group of cells I'm going stimulate, I'm gonna stimulate that one
09:12 cell in that uh that's in charge that whole group and that represents the
09:18 in which light needs to hit in to stimulate that ganglion cell.
09:23 the more cells you have obviously, larger the receptive field, the fewer
09:28 you have, the smaller the receptive . Okay, great dr wayne,
09:32 cares. Well, this is how deal with the process of acuity.
09:39 right, now, I'm gonna explain using modern tech that some may that
09:45 of you are going to get and of you just gonna sit there and
09:47 , I have no idea what he's about. Right, But you guys
09:50 what an HD Tv is. HDTV has how many pixels represented from
09:58 to bottom. That's that number they you 10 80. Close 10 2010
10:03 20 is sometimes what they seven twenties HD even though they say it is
10:08 right. So what it says, says if I look at a TV
10:12 count the pixels and go all the down, there's gonna be 1080
10:17 All right. You know, standard is 4 80. So take the
10:24 of the same size and you count pixels and would be 480 pixels from
10:28 to bottom. But if the TVs the same size, which tv has
10:33 pixels, the 4 80. All . And so you can look at
10:37 tv and watch tv show on a def 4 80 you look at and
10:42 , yeah, it's kind of And then you go and watch on
10:45 HD and it's like, oh, looks more realistic. And then they've
10:49 out with the new TVs, the K's. What does the 4K have
10:58 pixels from top to bottom? Also TVs that have 8000 pixels. And
11:03 with each iteration, what you're saying I'm taking in that space and I'm
11:08 it by that many more. So from 4 82,080 you basically have
11:13 the number of pixels from top to . So you get greater clarity or
11:18 acuity. Right? For four k you now have 4000 pixels. So
11:23 four times even better than HD. when you go to 8000 year,
11:28 better than 4000 and yada yada yada yada. And you can compare that
11:32 that little rinky, dinky nasty 44 p standard death and it's like it
11:37 looks real. In fact, that's argument. All right now, why
11:43 I bring all this stuff up? the number of photo receptor cells that
11:49 converging on that ganglion cell works in same way. The fewer number of
11:56 receptor cells I have, the greater acuity, right? Because you can
12:00 about like I'm gonna go, I'm go over here, look, the
12:03 way I can stimulate this ganglion cell if this particular photo receptor is stimulated
12:10 , you can imagine right next to there might be another photo receptor cells
12:13 it's going to a different ganglion And so what I've done is I've
12:17 a very, very small receptive I have a lot of these receptive
12:21 really, really close together. Then I'm pinpointing exactly where the light is
12:27 in terms of my retina. But I have a field like this,
12:31 is what you'd see kind of on periphery is like it doesn't matter,
12:35 can do this one or I can that one or any of the other
12:38 that are sitting in this and my basically that's that's kind of in that
12:42 over there right now we're talking I mean receptive fields that are like
12:47 big and even smaller, right? for your eye, that's a huge
12:52 . And remember what I asked at beginning at the end of class on
12:56 , I said, look, look that thing in front of you,
12:59 it's a piece of paper or some and look at something that you're looking
13:03 out is very, very clear. if you kind of look on the
13:06 and don't lose your focus on, kind of blurry, it's not clean
13:11 clear, it lacks acuity. And you can imagine now the way your
13:17 organized is in these receptive fields where have very, very small receptive fields
13:24 your forward vision right there in a right right there in the center of
13:29 you're looking. But as you move and further out on the edges,
13:33 have larger and larger receptive fields, enough to let me know that there's
13:36 going on. But it doesn't give the clarity. And so when I
13:40 something moving or something that catches my , I turned my head and I
13:45 my phobia right at what I'm looking . All. Right. So the
13:50 of convergence is responsible for the amount acuity, the more convergence you
13:58 the less acuity you have. All in other words, the more photo
14:03 receptors that are in that field, less accurate it can be so less
14:09 . Right? So it's the The smaller the receptive field, the
14:15 accurate or the more acuity I'm going have. All right. And so
14:21 or photo receptive fields are representative representative the ganglion self, the one that's
14:29 down at the end. Now, is coming back to one of these
14:34 fields and kind of using this idea this bipolar cell being in the offer
14:38 position. And this is what I'm of describing for you. So,
14:42 what we have is we have a field and we're using we're saying we
14:45 three um uh photoreceptors in our receptive . So you can see down here
14:50 our ganglion cell. But really what have is we have an on center
14:54 have an off center. All And so what's happening? He
14:57 look, if light hits here in center, then what it does is
15:01 turns on the on center and it this is bright and then it says
15:05 here on the edge of it you know, this is not
15:08 And so basically what it does, creates this contrast. And again,
15:12 not going to ask you if you this. I'm just trying to show
15:15 why we talk about this. All . Is that there's this complex networking
15:20 the gangling, sorry, the ganglion , the bipolar cells and the photo
15:25 cells so that your eye actually does or modulation of the signals even before
15:31 gets to the brain. And so brain already knows. Okay, the
15:34 hit the center of this field because turned on the ganglion cell that is
15:39 for that center of the field and the way, we suppress the off
15:44 . Yeah, this thank you. of like the innovation. Right?
15:53 the question is this really is just lateral inhibition. And the answer is
15:57 . It's very much like lateral And so there you want to have
16:02 with this stuff. Go and look optical illusions. And there's there's there's
16:07 one where it's like here's a bunch black squares, there's a white square
16:10 here's a gray square in the What is this really? A gray
16:15 ? And the answer is no, exact same color as the white stuff
16:18 . It's just that it's because it's by black. Your eyes create this
16:23 and says, oh, this is like the black. And so I'm
16:25 to fill in the color as a perception because of these on center off
16:33 optical illusions are you can have a with them for hours. We can
16:36 do this because this is what your is doing all the time with
16:39 I'm going to fill in the information on what I expect to see
16:44 All right. So, the summary all that is we have photo receptor
16:50 that have some characteristics. We have cells that are going to be stimulated
16:54 the photo receptor cells and then we the ganglion cells that represent that uh
16:59 receptive field. Okay. And what we're gonna do now is we're
17:02 to move and we're gonna ask the , right. How do we turn
17:04 these photo receptor cells? And how we respond a lot? How do
17:08 turn on our eyes so that we see? All right. And
17:11 the first thing we need to understand there is a pigment, this structure
17:15 photo pigment. Alright. There's actually parts to it. And so we're
17:19 to focus on the raw but this is occurring at the level of the
17:22 . All right. And the reason focus on the road because that's where
17:24 was most easily discovered. And basically , look in that rod we have
17:29 series of discs that are found in rod portion. Alright. And they
17:33 like a bunch of pancakes stacked on other and in the membrane of these
17:38 as we have this protein this molecule has a receptor like structure and then
17:47 in that receptor like structures some sort pigment that's behaving like a ligand.
17:53 right. I was like, so, this isn't anything new.
17:56 mean I've got a receptor and something's to it. Well, if I've
17:59 , something's bad. So that means going to happen. All right.
18:03 , the structure of the thing that like a receptor is called obscene.
18:07 right. And there's lots of I mean, there's one that's found
18:10 rod's Alright. We call that read . There's one in each of the
18:14 cones that we have. We call photo options. All right. So
18:18 just call them opposite molecules just to our lives easier because you have to
18:21 it, right? And they're all to different wavelengths, meaning they respond
18:26 a different wavelength of light. And reason for that is just because of
18:29 amino acids that make them up. right. So what they're doing is
18:32 at a certain wavelength you'll be able activate, say the S.
18:36 whereas in a different wavelength you'll be to activate the income and you notice
18:40 the massive amount of overlap. Please please do not memorize the wavelengths.
18:46 , I'm not interested in you knowing . Okay, we'll talk about why
18:50 is important in a second retinol is ligand portion and it's already there embedded
18:57 the opposite. Now it can leave it can bind back up. But
19:01 going to start with it bound up is literally taking a vitamin A molecule
19:05 clipping it at half. And so you see is you have this aromatic
19:09 in this long tail that goes with . All right. And so for
19:13 vitamin egg you clip it to have get to retinol walls. All
19:18 Yeah. The thing about retinol is bound up inside here and it's attuned
19:24 stimulate whatever type of option molecule you're at. So if you're in a
19:30 cone, it's bound up in there that it can cause the shape and
19:34 change so that you're responding to that length of life. Right now,
19:40 exists in two stages. There were different states. There's a active state
19:46 an inactive state. All right. when you find it bound up like
19:50 and in this particular shape, we'd that it's inactive. Now, we're
19:54 to come back to that a couple slides to see what it looks
19:58 When we're saying inactive, inactive. right. But I want to first
20:02 the photo options and color perception. right. The thing about these,
20:07 lot of people see, and this why I was trying to steer away
20:10 the red, green and blue. ? Because red, green and
20:13 When you think about a cone, thinking, okay, red cone must
20:16 to red and green must respond to and blue response to blue. And
20:20 vision is basically like a television set in the old day where you have
20:24 different lights in whichever ones you dimmed no, that's not how it
20:28 You can see here. I'm just use the red cause it's easy to
20:32 here. The range of stimulation for red cone is fairly broad. It's
20:37 from 400 to about 700. But the the massive or the greatest amount
20:42 stimulation starts around here. And then is the maximum amount of stimulation.
20:46 here is the least amount of Now notice what I said here,
20:50 degree of stimulation. Think about a . If you're in idle, you're
20:54 moving but your engine has a certain of RPMs going on, right.
20:59 if you press on the gas, can make the RPMs go up.
21:02 that's the degree of stimulation in terms your car. Right? And this
21:07 kind of the same thing. The you're asking is, how much am
21:11 stimulating this? And so uh photons different energy stimulate each rod or
21:18 each cone and rod uniquely. And so if the wavelength, remember
21:25 first day I talked about this at wavelength represents energy at different energies.
21:30 going to get different types of So here at 500, I am
21:36 of stimulating the blue cone. I'm the red cone more than I'm stimulating
21:41 blue cone. And I'm stimulating the cone even more than the red and
21:44 blue, all three of them are stimulated at different degrees and it's the
21:50 of those three stimuli and how they being activated. That allows you to
21:56 that color and the color that you're is a color between red or started
22:02 green and blue. Now, here's fun stuff. All right. How
22:08 colors do you think humans can perceive first asked the guys guys, how
22:14 colors can guys? How many colors humans perceive? What do you
22:19 100. Three 100. 300. , ladies, How many colors do
22:26 think? Thousands. All right. , here's the fun part guys.
22:33 many colors can you name? I'm them because they were like right here
22:36 the front. But I'm I could you guys six. You can name
22:38 colors. Yeah. Right. how many colors can you name?
22:47 . I heard I heard 1000 over . Someplace. Yeah. Right.
22:51 mean. All right. I'm going have fun. All right. What
22:57 jacket? Shirt? It's a What color? Jack is her
23:01 Guys, ladies, they're going to maroon or something. She he's already
23:08 maroon. Yeah. Well, it's it's true. I mean that
23:12 and men see the same color as can actually identify colors better. I
23:17 , that's it's a natural, it's natural phenomenon. Guys. We have
23:21 eight colors that we know. Roy biv and And the only reason we
23:26 those eight is because we took science third grade. All right. Ladies
23:30 five Blues, Go teal turquoise cerulean , Aquamarine. That's five didn't even
23:42 Navy. All right. I you know guys would look at this
23:49 right here and we would say it's . Ladies would be like, oh
23:54 corn flour. I'm not even sure even the right color. All
24:02 But what I'm pointing out here is see lots of colors. The actual
24:06 that we can see is in the of different colors. All right.
24:11 the reason is is because you're fine these three receptors to be able to
24:17 these different culture. Now notice here are the different wavelengths of visual
24:21 So there's your Roy G biv. you see pink up there?
24:25 but can you perceive pink? because pink is a form of
24:30 That's very, very light. All . It's kind of a mixture of
24:33 and red. That's just an So you don't sit there and
24:37 okay, well it's Roy G biv that's good enough. It's really there's
24:40 and there and this is even There are some women, not
24:45 there's some women who have an extra And it allows them to see 10s
24:50 millions of colours. All right. anyway, what I'm trying to show
24:57 in this particular example that 5 It just shows you the different degrees
25:01 stimulation. And so what color you'd perceiving as a result of that.
25:05 again, using the Roy G biv at the bottom. The process of
25:10 being able to perceive light is the of a process called photo transaction.
25:15 right. This is a G protein receptor pathway. And so this is
25:19 picture from your textbook. Right. I tried to color code everything so
25:23 you can see the name. We something called Guano late cyclists. Alright
25:27 late cyclists is sitting over here. job is to make cyclic GMP from
25:32 . Alright. So what it does it takes a molecule drops off the
25:36 phosphates and bends the last phosphate group that it's bound up and creates a
25:41 or cyclic structure. That's where its comes from. So cyclic guana seen
25:47 phosphate is cyclic GMP is good enough us. We have our photo pigment
25:51 we've already learned about. Here's photo over here. You can see there
25:55 the option portion inside there there is retina portion we have transducer. And
26:00 is just a G protein. All . And it was named transducer because
26:04 was the first one discovered discovered I , oh I'm trans inducing light energy
26:09 a neural signal. That's where the came from. All right.
26:13 Its job is when it's activated it another molecule called fossil diasporas. There
26:18 many fossil di ASti races, but not going to name which one it
26:21 . It's a fossil industries is the of fossil diocese races to take that
26:26 GMP when it finds it when it's and D. C. D.
26:31 it. In other words where I it was double bound basically what it
26:34 . It breaks that bond. And now you have uh cycling G.
26:38 . Sorry. You have GMP. from the cyclic GMP. That's what
26:41 trying to show you. All And then why we care about all
26:46 cyclic GMP and stuff is because we a channel. Alright. That's called
26:50 cyclic nucleotide gated channel. Alright. basically when it's cyclic GMP is
26:56 what it does it binds up to channel causes it to be open and
27:00 that is open it allows sodium to into the cell. Now I'm gonna
27:05 you to think about when we learned neurons. When sodium comes into the
27:09 . What happens to the cell? d polarizes good and it becomes
27:16 Right? That's the normal situation. we're dealing with a neuron and a
27:22 receptor cells a type of neuron. what we have here is we're basically
27:26 when this channels open sodium is coming and the and the cell is de
27:31 and it's becoming activated. All right . There we go. So this
27:42 a picture I drew years ago for class and I'm just it's the same
27:46 that we just looked at with my . All right. So all the
27:49 players are still there. I'm going go through again, I've just drawn
27:52 all out so I can show you happening in the photos receptor cell in
27:58 absence of light And when the light present. Alright. And so our
28:02 stage is here in darkness. All , no light present. What's going
28:08 ? Well, the one light cyclist always always always making cyclic GMP.
28:13 so what that means is is the of cycling GMP inside the cell is
28:17 be fairly high when you have a of cyclic GMP that's going to bind
28:22 to that receptor that channel. So, you're just trying to show
28:25 is bound up which caused it to some sodium comes in. And that
28:29 there's lots of sodium inside the So, in darkness, we have
28:34 of sodium inside the cells. So cells d polarized it's active. Can
28:40 see in the dark? Can you it was pitch black? No
28:45 No, you perceive darkness. So, something's fishy here. You
28:52 when the cell is active? I'm darkness and the answer is yes.
28:58 . So, what that means is fishy is happening downstream that we got
29:01 deal with. And we'll get to moment. But I want to show
29:03 what's happening in the light. Oh, first up, and this
29:08 something that your book addresses. I want you to spend a lot of
29:12 trying to understand this. But if is always coming into the cell.
29:16 the inside of the cell will eventually full of sodium and then the cell
29:19 stop being polarized. Right reach Well, we can't have that
29:24 So, what we have is we a current. So basically you have
29:27 pump. So as the sodium comes , you pump it back out and
29:30 it just keeps it rolling so that cell remains deep polarized. Okay,
29:36 what the dark current says. Oh, it will be but not
29:44 now. Okay, you're getting ahead the story, which is okay.
29:49 right. So, you can see this in the dark. I'm deep
29:53 . So what am I doing? releasing neuro transmitter. All right
30:00 let's talk about light. Here's our photon hits that retinal molecule.
30:06 The retinal molecule is the one that's to light. Option is sensitive to
30:12 retinol is doing. So, the we're asking here is okay, what
30:16 happening when light comes in? what it does is it changes the
30:21 of the retinal molecule. It's in cIS form and it's going to be
30:26 into its transform. Alright. And we'll see what that turns into what
30:31 looks like now if you have not to If you've not taken organic
30:35 you don't know what cIS and trans . That's fine. So you can
30:38 of see here, It's basically saying at the 11 carbon, it has
30:45 crook, right? It's the shape a hook in the long tail and
30:51 sitting there inside that opposite molecule. when light comes along, it changes
30:57 shifts that that that bond so that now have a really, really straight
31:03 . Now, you can think about this, well, I'm not active
31:06 there's not like I'm inside my I'm inside the option and it's
31:10 okay, I'm just kind of sitting . But when I change my
31:13 I'm no longer comfortable inside the So I change the shape of option
31:17 fit. Okay, And so what done is I've gone from an inactive
31:23 to an active shape which causes the to be an inactive form and becomes
31:29 . That kind of makes sense. right. And so the transform is
31:36 allows everything to start moving in And what we're gonna need to do
31:42 once we've converted into this form, could never re stimulate that.
31:46 we're gonna have to change it back the cyst form before we can ever
31:50 anything again. And so there's a process that allows that to happen,
31:54 we're not going to go step by through. But I'm just gonna see
31:57 there it is, right there. , so the first thing that happens
32:01 comes in stimulates the retinol if it retinol, you don't activate or stimulate
32:08 cell. So what you're doing is activating the retinol to retinol becomes active
32:12 everything downstream turns on. All So here you can see I've turned
32:16 on the trans has activated the system now it's going off and doing its
32:21 . It's going to get converted back the cyst form. All right,
32:24 what is the next step? the photo pigment which has been
32:29 activates the transducer. Transducer is the protein. It kicks out a GDP
32:35 replace it with a GTP once it uh replaces that that's its active
32:41 So the changing shape of one changes shape of the other. Which allows
32:45 bring in a new molecule that brings with it. That GTP activated alpha
32:53 goes and activates Foster dia stories what fostering diasporas do? Well, it
32:58 all that cyclic GMP and it basically chewing it up. Now. In
33:03 this process, we're still making cyclic . But the rate at which we
33:07 it down is faster than the rate we make it. And so what
33:10 is the amount of cyclic GMP becomes and less and less inside the
33:16 If you have less cyclic GMP inside cell, that means you have less
33:21 GMP to bind to this receptor. that's what happens less cyclic GMP.
33:29 there's like less there now. So means that receptor that channel closes when
33:34 channel closes, sodium can't come If sodium can't come in the cell
33:40 longer do polarize, it hyper See there's that term Okay and when
33:46 hyper polarized you're no longer releasing So what you're doing is in the
33:54 , you're activated and you're releasing neuro and you're stimulating. What's the next
33:58 in the sequence? You remember bipolar ? So you're stimulating the bipolar cell
34:04 the next step in the dark. in the light, what you're doing
34:08 you're no longer stimulating the bipolar And so what happens is this is
34:16 process here just doing the compare and . So in the dark I'm stimulating
34:20 bipolar cell. But here I'm Well what we're releasing is an inhibitory
34:28 . We're basically saying to the bipolar in the dark there's no light.
34:33 do anything. So the bipolar cell sits there and go, okay nothing's
34:38 on. But in the light what is is I'm not inhibiting the bipolar
34:44 . So the bipolar cell naturally deep . It wants to be like the
34:50 . So it wants to be de all the time. And so what
34:52 does is when nothing when nothing is to tell it to not be polarized
34:57 polarizing that tells your brain light is and then it stimulates the ganglion cell
35:03 and the ganglion cell says ah within field I have been stimulated by light
35:09 it sends that signal onto the brain say this is where light has
35:13 So your perception of light is a of light hitting the receptive field.
35:19 it's a function of turning off the receptor cells. Now some of you
35:25 sitting there going on this stupid, don't they make it easy for
35:28 And here's the answer. I want to think about the day right
35:32 Right? Right now we're in there's more darkness than there is
35:37 But humans haven't always been. Most are not a species or an organism
35:43 sits in one place, primarily We tend to follow our food and
35:48 tends to follow the sun because that's all the other animals and the other
35:53 are. So most of our life spent in light. And if I'm
35:59 activating cells, that's more energy, ? If light is where I'd be
36:06 energy then I'd be spending more That means I have to eat
36:09 And I already had enough. Me you right now. So it's easier
36:16 activate cells when you have, you , for the shorter period of
36:20 That's more energy efficient. So photo cells are active in the dark,
36:26 less energy to do that. I show you the math. But it's
36:36 . So I've already mentioned this, told you I'd be come back like
36:42 kid getting blinded because he's staring at sun and basically says, look,
36:47 able to adapt to different levels of because I have cells that respond to
36:52 differently. We've already talked about that adaptation is just adjusting to low
36:56 Which type of cells do a better of adjusting or being activated in low
37:02 the rods, right? But they longer to adapt. And so that's
37:07 it's harder to it takes longer to to a dark room that it takes
37:11 adapt to a light space. Light is basically into the high light
37:18 Now, a lot of stuff in , I don't need to know any
37:22 it. You just don't understand what says. So, it says,
37:25 , here's my 11 cis retinal, turns in that trans retinol. What
37:29 I do with that? Well, got to convert it back to the
37:32 retinal in order to make it So what I'm gonna do is I'm
37:35 boot out that trans retinal, I'm transport it into those um retinal pigmented
37:42 cells. And because those cells have in there basically blocking out light.
37:48 so in there I can do these tiny molecular or chemical reactions to reshape
37:53 and hide it from the dark or from the light and then I can
37:56 it back once I got into the shape and then I can put it
37:59 into the cell only to be activated and just repeat the process. All
38:04 . So in essence I'm converting it I need to have the cyst form
38:10 . How long did it take? , for Raj, it takes about
38:13 minutes. For a cone. It about three minutes. All right,
38:19 , that's why it's harder. Or takes longer to adapt in the
38:22 Because remember, rod cells are basically out, everything is activated. And
38:26 , you're constantly trying desperately to get cyst forms back rods. It takes
38:31 or it takes more energy to get activated. So, it's really easy
38:35 convert them back. So, this here dark adaptation adaptation has different times
38:43 order to do that adaptation because of these steps that take place elsewhere.
38:51 other thing is that cones tend to their own retinol as well.
38:55 you don't have to send it to cell to get fixed. It's like
38:59 your phone in, right? You get to have your phone for a
39:01 of days when they have to replace screen, right? That's in
39:05 what you're doing is like I broke retina. Can you go fix
39:09 It's like, sure I can fix for you. But you have to
39:14 . That's what the seller doing. , what is the pathway here?
39:20 right, there's a lot here to and I've tried to just break it
39:25 to the very simple, right? , when light hits the eyes,
39:28 hitting the photo receptor cells stimulates the cells stimulates the ganglion cells. The
39:33 cells are sending impulses along their This is down action potential. And
39:38 those axons do is they form the nerve. And so the optic nerve
39:44 the axons as they converge and exit of the eye, you can see
39:49 they cross each other. There's something the optic eye asthma. All
39:53 The optic nerve, optical asthma. happening here is you're crossing fibers So
39:59 fibers that are found on the medial . Right? So you can see
40:05 Well, sorry here and there are to go to the same side.
40:10 right. The fibers found on the here, but the medial side there
40:14 going to go to the same And the reason for this is to
40:17 that the brain gets information from both and actually understand what's going on.
40:25 going to happen is the optic Iseman into the thalamus and it goes to
40:29 specific location called the lateral gene ejaculate . The reason we named this is
40:35 we're going to see we've already seen other nuclei in the thalamus that RG
40:41 nuclei. All right. So this the lateral one. We're gonna see
40:45 here in just a second and then there information is processed and then then
40:51 on to the primary visual cortex which v one There we go a lot
40:57 stuff here that you don't need to . Again, I'm throwing up here
41:01 just show you it's a complex All right. Here we talked about
41:05 we talked about the cortex having six . Remember me saying at least
41:09 twice, maybe three times. I know if this is just showing you
41:12 is just three layers. Right? , they're layer number one. There
41:14 layer two and three. Here's layer . Here's more layer four's there's five
41:19 six and so and so and so . All right. There are six
41:23 . And what I want to point here is just what we're doing here
41:26 there's different areas in these court in cortex that process information separately.
41:33 So I mentioned you colors is processing called blobs. Right. Remember
41:40 It's like you don't need to know blob is I don't know. The
41:43 is trying to identify a blob and a blob is hard enough but showing
41:48 up here there's a block in between blobs are the inter blobs. It's
41:54 . Thanks. All right. what better blobs due process spatial
42:00 So, color is the blobs spatial is in between them. All
42:06 We have different types of cells. of cellular cells and magnus cellular
42:10 So, this magnet cellular cells in with parvo cellular cells deal with high
42:17 black versus white. Right? So you're looking at something what you're doing
42:21 your brain is trying to see how brightness is there and it creates this
42:25 this contrast. So it can best it. So different areas within the
42:32 do different things with that information. your eyes are not cameras and you're
42:37 just recording movement and color and spatial and stuff like that. It's basically
42:44 everything down processing that success in that separately and then it puts it back
42:49 together for the idea of perception And what this is basically showing you.
42:55 is just showing you the five visual , right? And there are more
42:59 at least 20 regions of the cortex are known to identify vision. So
43:07 just kind of showing you some of . So we've already said that the
43:10 . One key thing here to remember that it represents your visual field.
43:15 basically it's mapped out if you took retina and flattened it and basically you
43:19 see that different areas in there are in a map in v.
43:26 All right. Visual memory basically is to be in V two. That's
43:32 shaped spatial position, size, color shape. So if I showed you
43:35 object you'd be able to go, know what that is. I've seen
43:37 before. That's a and then whatever is, tennis ball. Okay,
43:43 three deals with the question of Right? Oh that thing is
43:48 And so I can see that this here and then a couple seconds later
43:52 object here they're related because it moved here to there. Can you believe
43:57 something that you just naturally see things and you're like okay it moves but
44:02 brain breaks it down in terms of you know both vertical and horizontal movements
44:08 everything. And it basically says oh movement from that object. I saw
44:11 here second ago. Now it's over , it's the same object, it's
44:14 moved. All right. Um Then have basically what's the orientation? Um
44:21 picked up an app on my phone other day because I was really really
44:23 . You've probably seen it if you any sort of game on your on
44:27 phone you've probably seen it that picked three the three D. Uh match
44:32 . Have you seen that game basically big pile of stuff and you're supposed
44:35 match things in there and pull it . If you see if you have
44:39 game you're not play for. I you've seen that uh that ad for
44:43 ? Right? So I picked it and basically what it is as you
44:46 see there's an object that might be upside down or twisted stuff. But
44:50 can identify? Well because of what's on before And then v. five
44:56 also again perception, emotion. And are just the basics. I mean
45:00 at the map. So you see a V. Seven V. Three
45:03 there's a VP that's not vice All right. But there's just there's
45:09 and more and more areas in Okay, so the idea here is
45:15 is not simply movement or me seeing and recording the movement. It's me
45:20 it down and breaking apart and my then putting it back together in the
45:25 of perception, ready to go and the air. You have questions about
45:31 stuff. Mm Okay. Yeah. have you guys, how do you
45:47 look at people's ears before? I I did in the other class.
45:50 you look at something, you look the person next year, if you
45:52 see their ear, look how weird are. They're they're weird. You
45:57 at them, they're just like All right. And that shape is
46:02 for a reason and we're going to to that. Hopefully at the end
46:05 the class here to say, when you look at an ear,
46:07 , it is weird looking, but has functionality to it. All
46:11 It's not just like some random skin your your body is like a I
46:15 know what to do with this. just it actually has shaped for a
46:18 . Now what we're locked talking when talk about the year we typically think
46:22 hearing, but the other half of job of the ear is equilibrium.
46:26 right. And when I say you know when you get dizzy,
46:29 what we're talking about the lack of ability to know what your position of
46:33 head is in space. Okay, we have three parts to the
46:37 We have the external ear and we the middle ear. So this really
46:41 the external ear right here. There's middle ear. And then we have
46:44 inner ear which is this weird looking in here. The external middle
46:49 the job in a very basic is to take sound waves and transmit
46:55 and then amplify them to the inner . All right. So their job
46:59 to project to the inner ear. then once that sound wave gets to
47:03 inner ear that the inner ear is for processing that sound wave. So
47:07 have the perception of sound. All . So there's two structures in here
47:12 we're going to look at and we just kind of point them out here
47:16 . This thing that looks like a snail shell is called the cochlea that
47:22 a role in hearing converting sound waves the neural impulses. And then this
47:27 over here that looks like some sort mutant snail that has come out and
47:30 devouring the inside of your head. is the vestibular apparatus that is responsible
47:35 equilibrium. So you can see it's of divided into two parts All right
47:41 in terms of the anatomy of the ear. This thing is called the
47:45 or the oracle. Alright. Its is to collect sound and then direct
47:51 into the ear canal or the or external acoustic or auditory meet us.
47:56 see all three terms external auditory meet external acoustic meters, or the ear
48:02 . Now in the ear canal, is responsible for directing sound of the
48:06 panic membrane, you're gonna find hair you're going to find some unis glands
48:10 the purpose of that is to catch sorts of horrible nasty things that are
48:14 to get into that little time. hold in your head. Alright
48:18 google is our friend. There's wonderful of people finding a little tiny spiders
48:23 their ears. There's the one of cricket, you know, a guy
48:27 complaining about his ear itching. Finally to see a doctor and there's a
48:30 that had worked its way into its . This is just nasty stuff out
48:35 . And this is why we have . All right, so, we
48:39 see the nasty stuff because let's face , those things have like 20 million
48:45 . You're gross. But we dig All right. Lastly we have the
48:50 panic, membrane, tim panic. can think in terms of a
48:53 It's basically like the skin of a that's been pulled over. So it
48:57 the entire length of the acoustic meet . And it separates out the external
49:02 from the internal ear And when sound hit it, it vibrates at the
49:07 of those sound waves inside the middle . We have what is the tim
49:14 cavity? Alright. And that's to it from the auditory tube. The
49:19 tube has another name named after the named named It's called the eustachian
49:23 basically station to where the auditory tube the middle ear up into the back
49:28 the throat. You ever had your get all stuffy and clogged? What
49:31 you do? Right, pop your . Right. And what you're doing
49:36 basically your aquila, breaking the pressure the middle ear to the external
49:41 which is what would be in your cavity as well as out here in
49:45 external environment. All right. And reason we need to do that is
49:49 if there's unequal balance of pressure, the vibration of the tim panic membrane
49:54 going to be uh muted. And the idea is to create equal pressures
49:59 either side. So the timpani membrane vibrate at the frequency that it
50:04 Now in here, Right? We the tim panic membrane separates from the
50:11 environment. But we have two little that are responsible for separating the middle
50:16 from the internal ear. The one most important is the oval window.
50:22 ? There's a membrane that sits over oval window. There's one that sits
50:25 another that's called the round window. the oval window first, round window
50:28 second. All right in here we three bones, the malice and the
50:34 and the staples or the hammer. anvil and the stirrup based on what
50:39 look like. The strip is the that looks like a stirrup. The
50:43 two doesn't look like a hammer and anvil. But I think it's just
50:45 way that they interact is how they them. All right. And so
50:49 happens is you can see here that is associated with in tim panic
50:54 The malice is associated also with the and the Incas associate with the steps
51:00 the state is sitting over the oval . So when the tim panic membrane
51:06 , the malice moves, the Incas and the staples moves. And these
51:10 bones together serve to amplify that sound . All right now, why do
51:17 need to amplify well? Because the ear is filled with fluid and that
51:23 needs more energy to cause it to air. You don't need a lot
51:26 energy to cause a membrane to move the air. But if you have
51:30 on the other side, you have really work it. And so that's
51:34 reason for the amplification is to amplify the strength of the sound wave.
51:40 change the frequency, but amplify it that it gets transmitted to that oval
51:46 . So when the Tampa nick membrane , the oval window moves and moves
51:50 the same frequency. There's also some in there. They're called the tensor
51:54 . An attempt for in this as tedious. Alright. And they sit
51:59 those bones, the malice and the and the state please anyone who's been
52:03 a loud concert. What happens when music comes on? It's really
52:07 What do you do cover your And then after a while you take
52:13 hands away, music sounds just Alright. Three, you cover your
52:17 . That's a natural reflexive response to the ears. But you're muscles here
52:24 responsible for d amplifying the amplifier. right there, the negative amplifier.
52:31 if you're getting loud sounds, you're to still get amplification. So what
52:35 want to do is you want to that amplification so the muscles contract and
52:38 prevent those bones from moving quite so . Still get the same frequency,
52:42 not about the amplitude. So they sound to sound normal, I guess
52:51 loud. So then we get to inner ear and these are structures.
52:56 two structures and this picture is not do any show you these two
53:01 We're going to see it more on next slide. It's what we call
53:03 bony labyrinth and that's really what you're here is the bony structures and then
53:08 it are the member nous labyrinth. right now the bony labyrinth has within
53:14 a bunch of cavities and in these there's fluid which is the fluid that
53:19 have to move around in order to sound. All right. The fluid
53:25 inside that is called parallel. If this fluid is very similar to the
53:30 around your cells. So like interstitial . All right. The three structures
53:36 the bony labyrinth include the coke All right. The one to the
53:43 semicircular canals and in this area, in here where you can see is
53:50 is called the vestibule. The memory's are inside each of these.
53:56 when you look inside them, you're to see the bony parts. And
53:58 there's the structures that are set apart membranes. And it's these member nous
54:06 that are again filled with fluid. have a different fluid they call it
54:09 lymph. That fluid is like the fluid so very different. It's not
54:16 the fluid that you'd see surrounding the . Like the parallel these membrane tubes
54:23 the bony labyrinth have names. We the cochlear duct which would be inside
54:27 cochlea. It's this structure where you the hearing organ, it's called the
54:34 of corti. So this is where gonna find the receptor cells that allow
54:38 to perceive the sound waves inside the . You have these two structures called
54:44 homosexual which we'll talk about on Tuesday week, they play a role in
54:49 equilibrium or balance. And then the canals has a tube within its called
54:54 semi circular duct. Um And these also organs of balance. So what
55:01 want to focus on here is I'm to focus on the memories labyrinth and
55:05 cochlear duck inside the cochlea. To understand sound, that's what we're
55:11 today. Now to understand sound, need to first understand what it
55:15 We looked at light, we said is photons, packets of energy is
55:20 as wavelength. And it had this weird wavelength thing. Sound is simply
55:25 molecules or molecules bouncing off each All right. So what happens is
55:30 I'm speaking or projecting a sound, pushing air that air compresses against air
55:35 here bounces off that air and then away. And so what you do
55:40 you create a wavelength that basically So if you want to picture it
55:44 you can take a picture rope and can just snap the rope and you
55:47 watch the wavelength and that's what sound . It's basically that rare faction.
55:53 compression. Alright. So basically as go up and that would be the
55:57 . So here's the compression. There's rare faction has two characteristics. All
56:03 . Oh also because this is a of energy as I'm I'm using energy
56:07 move those molecules the further as to molecules collide and hit things, they
56:14 energy is lost. And so the the sound travels, the less energy
56:18 has until it dissipates. And so loses its amplitude. Right? So
56:23 I whisper your talk me Right? when I yell, sound travels
56:31 Right? So, characteristics of sound , they have a frequency that is
56:37 in hertz. That's pitch. It's notes and low notes. Okay?
56:41 when you hear frequency, think high versus low notes, pitch intensity is
56:46 amplitude. That's how tall the wavelengths . All right. So, the
56:51 the less intensive sound, the the more intense in sound. All
56:56 . But it doesn't have to do pitch. You can have very loud
57:00 notes, you know, very high notes. Right? And everything
57:05 between. So, intensity amplitude decibels . All right. So, what
57:14 looking at in our cartoons? here you can see here is our
57:18 a There's our vestibule. There are semicircular canal. So we're gonna be
57:22 here inside the cochlea. And you see it's a snail shell. It
57:26 snail shell. It basically coils itself . Right? And you can imagine
57:31 there, if you took a if you're looking at one of those
57:34 , you can see that there's actually chambers separated by membranes. So in
57:40 this is membrane that's membrane. And you have two chambers. This is
57:44 picture of that unwound. All So what we're saying is it's not
57:48 wound up, like if we unwind this is what looks like. And
57:50 can see here here's our oval There's are staples. So, there's
57:54 tube inside that goes up, goes the way to the top of the
57:59 and then turns on itself and comes the way back down again.
58:02 here it is. Going up to top. This is it coming back
58:05 again and it comes all the way around to the round window. And
58:09 can see there's fluid inside each of . Now, if we were to
58:14 these things, we're going to call top tube. One that's from the
58:19 window. We call that the scallop . The rest of the vestibular duct
58:24 its name. All right. It's is bone but its floor is a
58:30 . All right. The name of membrane? The vestibular memory. How
58:35 . All right. So, I a vestibular membrane and then in down
58:40 in the bottom I have the skeleton or the tim panic duct.
58:45 So, here's a scallop, vestibular . Pani. It's one long
58:49 We just basically say here at the we flip and that's called the helicopter
58:53 . We flip and then we go other direction. So, sitting between
58:57 scallop is stimulating the skeleton. Pani our cochlear duct also called the scalar
59:03 . All right. So, you see I have a membrane have a
59:06 . So, the roof of the panty is the basilar membrane which is
59:11 , but it's really referring to that chamber. And so what we say
59:17 the roof of the scallop media or cochlear duck is the is the basil
59:22 is a vestibular membrane on the bottom here is the basilar membrane and then
59:28 in the middle we're going to see our structure called the organ of
59:32 And it's this structure here that plays role in hearing fluid in both
59:40 fluid in the middle chamber. Out , parallel in here in the lymph
59:51 at the spiral organ or the organ corti. This is our hearing organ
59:57 . Here's a close up. You see what we have is we have
59:59 unique structures called hair cells. These the receptor cells of hearing their mechanical
60:08 . What they're looking for is they're for movement. Above them is another
60:15 membrane. It basically over lies and in contact with these hair cells.
60:23 then each of these hair cells are with a neuron. And basically what
60:29 do is they go and they form is called the cochlear nerve. All
60:35 . So, this would be the ganglion as they form the cochlear
60:40 All right. This is just showing the arrangement. We can see that
60:45 one row of what are called the hair cells there's are one row and
60:49 is going the entire length. remember we unwound it make sure when
60:53 . So we're basically saying the whole of that cochlear duct looks like
60:58 So up here, this would be skeleton stimulate switch switches on itself comes
61:02 to skeleton. Pani along the entire in that cochlear duck, we have
61:07 structure. So this is coming out you and says there's one hair cell
61:11 here and there's three hair cells over . This one hair cell. And
61:17 there's the row of them going those are the mechanic receptors there.
61:21 job is to actually detect the Their job is to detect movement inside
61:29 cochlear duct and to tell us that where sound is occurring out here.
61:35 it out here. We have the hair cells. Their job.
61:40 I do have batteries. It's very frustrating. Where are my batteries?
61:50 , I can feel it. I , nope. Well, I'm out
61:56 batteries. I'll have to I'll have point over here Well, I'm gonna
62:04 to do something. I'm not good this. This is why I stick
62:07 the pointer over here. Those outer cells. Their job is to modulate
62:19 degree of movement in there. All , so, what's happening is we're
62:25 we're gonna kind of paint a big . We're gonna try to put it
62:27 together. All right, So, we have here is we have this
62:34 membrane on which these hair cells are up. Alright. And what's going
62:39 happen is is when sound comes it hits that tim panic membrane which
62:44 the malice, the Incas and the police to move, which causes the
62:48 window to move back and forth. ? Which causes the fluid to move
62:54 that tube. So, here, can see the oval window and that
62:58 is now moving at the same frequency that sound way. All right,
63:05 , you need to kind of use brains to think about this. All
63:08 . Because it's not gonna be visually up here. Sound wave has a
63:11 length to it. Right. That if it's a short wavelength it's going
63:15 go up and then it's gonna come down in a very short length.
63:19 if it's a long wavelength, it's go up and it's gonna come down
63:24 a long distance. Right? where it's going up and coming down
63:28 going to be dependent upon where or the degree of stimulation. All
63:37 So, the oval windows vibrating the wave comes in and depending upon its
63:43 , it's gonna hit at a different along that vestibular membrane? High notes
63:50 closer to the front. Deep notes closer to the back and then the
63:56 notes in between. And so, happening here? You're displacing the vestibular
64:02 . I'm going to go back a here. So, if I'm a
64:05 note, I would be displacing the over there. If I'm a low
64:08 , I'd be displacing the membrane over . Okay, what does displacement of
64:12 mean? Means membrane moves. So, I have my vestibular
64:16 I have my basilar membrane down I've got the territorial membrane here.
64:20 , when I'm displacing the membrane at particular location, that means I'm moving
64:25 . If there's fluid down here, fluid is going to then push on
64:31 basilar membrane so they both move together far so good in between a sectorial
64:43 . This is just showing you the of the basilar membrane now.
64:48 As the base color in the vestibular membrane moves first at a particular
64:54 basal membrane moves at a different at same location. All the other places
64:58 move just at that particular location. fluid inside moves. And what it
65:03 is it causes those hair cells to back and forth. The territorial membrane
65:08 move at all. They just basically there and it forces the fluid to
65:13 of move in a circle over those cells. So, the hair cells
65:17 basically move, waving back and forth the movement of the fluid and they're
65:21 the movement of the fluid at that location. All right. If you
65:26 visualize this, she's gonna be my memory for a second. Put your
65:29 out. It's perfectly still see it move. It doesn't move at
65:35 Right. And so, you can here, Here's the babies learn the
65:39 membrane. Alright moving up and A little hair cells are sitting here
65:45 the basilar membrane and as they move they push up against that textural membrane
65:49 move down. So they're basically moving and forth in response to this movement
65:54 going right here. When those hair move, what you're doing is you're
65:59 those little tiny hairs on the the sterile cilia and the direction they
66:04 basically opens and closes channels that causes polarization and the hair cells. And
66:10 those hair cells move, I'm detecting movement and said, oh at this
66:15 frequency these hair cells move. And the brain perceives sound because of movement
66:21 that particular area. Go back Yeah. Oops. Wrong direction.
66:34 you can see down here here, that basil er membrane or Sorry,
66:38 particular memory? There's a basilar And where am I doing this?
66:42 , if I have a high all that movement is occurring right
66:46 If I have a low note, going all the way over there and
66:49 that energy that goes through the Remember it has to go someplace and
66:53 it moves back into the skeleton Remember we have the scallop is stepping
66:58 the top. Cochlear duct in the skeleton panty on the bottom. So
67:02 energy short cuts its way through. basically I'm going to go this way
67:06 then I'm gonna go back to my window and a round window absorbs the
67:11 . All right. You want to what that looks like. You guys
67:13 see those stress toys where you're basically in? The eyes will bug
67:16 Right? The reason it does that because the energy that you're using to
67:20 it causes those little eyes gopal. that's what the round window does.
67:27 . Only one person laughed at That means you guys are really,
67:31 nervous about this. All right. , you think about the steps.
67:36 hits my oracle travels through the auditory , right? Hits that tim panic
67:42 cause it to vibrate. Cosmopolis. staples to vibrate, causes the oval
67:46 to vibrate. It's all at the frequency. Right? So, it's
67:50 note, Right? You know, whatever note you obviously when I'm
67:54 I got notes going all over the . So you can just see how
67:57 it's able to do this. But picture a single note. That single
68:00 causes that vibration at that frequency and it travels to a specific location along
68:07 stimuli membrane causes movement at that particular , causes the movement of the basilar
68:14 , which causes the hair cells at particular location to move. Which then
68:17 where you're gonna get that perception of . The sound then travels back to
68:21 round window. So the energy is . So it's not just bouncing back
68:25 forth and doing all sorts of weird inside that tube. Mhm. So
68:33 that hair cell. What is the cell? It basically shows you here's
68:37 stereo cilia. They're attached, there's large one in the front that's called
68:42 . And then the series of hair attached to it seriously. And if
68:45 bending towards or away from the penicillium the degree of opening of channels.
68:49 you open towards the penicillium, you're up more. So you get greater
68:54 polarization. And if you move away the penicillin, you get hyper
68:58 So you get less signal. And when you're stimulating the cell, what
69:01 basically doing is you're saying send a here. I mean from here that
69:06 the brain this is where stimulation So that you can perceive the
69:10 So notice you're not actually changing sound . What you're doing is you're detecting
69:15 . It's a mechanic receptor, You're just looking for sound waves or
69:24 . So the frequency is determined by on that membrane I'm hitting it.
69:34 learned about dogs, dogs can hear a higher pitch, right?
69:38 Because their membrane vibrates at those higher nearest their oval window, learn about
69:48 . But the big ones, what they hear it? Very low
69:52 Now, the reason for that is sound waves don't travel well in
69:55 So the best communication they have is these larger wavelengths wet sound waves.
70:02 they have uh their their inner ears detect at that lower frequency. We're
70:09 of stuck in the middle with like of a lot of high frequency is
70:12 of low frequency are kind of in middle, you know? And so
70:16 frequency discrimination is dependent upon where that's particular part of the cochlear duct is
70:24 stimulated in terms of amplitude. That's how much we shake that membrane.
70:31 right. So it's soft sound will not so much energy. So you
70:36 less vibration. A very loud sound the same frequency is very strong
70:42 lots of energy. And so you that movement in the you know,
70:47 would be greater movement. So you that greater movement. That's how you
70:52 , something's loud or not. So the ear, right from these hair
71:04 they're going to form the cochlear nerve is going to be formed the vestibular
71:10 nerve ultimately. And what that's gonna is that that nerve goes into,
71:17 me, goes into the medulla, goes into these nuclear called the cochlear
71:23 . Alright information with the cochlear nuclei go over to the superior olive which
71:28 you to localize sound and how it this is really, really awesome.
71:33 we're not going to talk about No, I mean it's it's complicated
71:37 engineer if you're an engineer and you , I've got a couple of engineers
71:40 the upper classes. They get really because it's all circuits and its length
71:44 circuits and how these nerve fibers or . Alright. But here, what
71:49 doing is you're localizing sound and then go up to the inferior calculus in
71:53 midbrain that helps you to do the of the lab sounds, right?
71:58 do you know what I'm talking Right. So if you hear,
72:02 , what do you do? U right. That would be reflected a
72:06 sound. All right. And then there we go up to the
72:12 that's the medial lenticular nucleus. And there you go to the primary auditory
72:17 , which is where we are able process that sound and perceive it.
72:24 , When you hear uh what are hearing? Horn or Professor making stupid
72:32 . All right. Now, I you weird things. All right.
72:36 two slides. And then we got . All right, So there you're
72:40 at that here, it is a structure. You know, go and
72:42 at your own ear if you're uncomfortable at other people's ears, right?
72:46 if you're afraid to show your ear somebody else. All right. You
72:49 see it's just weird. But the it has this weird shape is because
72:53 sound waves hit it bounces off these in different ways and this is how
72:58 able to localize sound and from where coming in the vertical plane. All
73:04 . So basically how it bounces off going to change depending upon the direction
73:10 of where it's hitting these things. right. That's what this is trying
73:14 show you. All right, well about the horizontal plane? Alright.
73:20 direction is it coming from? Well is now more dependent dependent upon uh
73:26 delay between the two years. All . So when you have high frequency
73:32 , what happens is you create what called a sound shadow. In other
73:35 the noise hitting on say the sound coming from this direction, the sound
73:39 on this side is going to be louder than the sound on that
73:43 All right. And so your brain the intensities and so it says so
73:49 softer on this side than that side it's coming from that direction.
73:53 But there's also when you have these frequency noises, they travel you know
73:58 have these different wavelengths and so there's delay. So in a high or
74:03 frequency noises like sounds coming from this and it hits here first and then
74:08 here second. And so that the perceives the timing difference and says oh
74:16 the direction it's coming from now. know you're ready to get out of
74:20 but I'm just gonna ask you you love your headphones, right? Yeah
74:23 see you guys walking around, anyone have the three D. Headphones or
74:27 they're really the virtual surround sound right? They're awesome. And what
74:33 do is they take advantage of all different characteristics that the brain has and
74:38 the frequency, distance and frequencies that you a perception of where it's coming
74:45 . Kind of cool. All you guys, I will see you
74:48 thursday. We will continue talking about ear. Hmm. Mhm.
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