| 00:02 | Everybody ready for the weekend. It's , yeah, again, I apologize |
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| 00:09 | those of you who have Friday classes your schedules next semester today, what |
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| 00:16 | gonna do is we're going to try finish up with the nervous system. |
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| 00:22 | so we're going to be dealing with last special since and then we're going |
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| 00:25 | kind of wrap up with some We're going to look at neural |
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| 00:29 | for example, we'll be looking at or localized circuits, we'll look at |
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| 00:36 | reflex. So we're just kind of of jamming everything here together for this |
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| 00:40 | little unit. Um And what I do, uh just kind of to |
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| 00:46 | you what we've been looking at. , we've been going through the special |
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| 00:49 | , we kind of skipped over the special, the, the, the |
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| 00:53 | of touch, you know, and on and so forth. But we've |
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| 00:56 | at, um, you know, sense of smell and the sense of |
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| 01:00 | and what were you detecting when we doing that? What, what were |
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| 01:05 | types, what, what, what of modality are these are these particular |
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| 01:09 | of senses? Chemical good, very . And then uh we just finished |
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| 01:15 | the, with the eye and so eye detects what, what is its |
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| 01:21 | light. And so we're dealing with reception and really, we're detecting just |
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| 01:26 | small bandwidth of, of electromagnetic right. So we're now going into |
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| 01:32 | different type of reception, we're going mechanical reception. And so when we |
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| 01:37 | about hearing and balance, we're talking detecting the movement of something. All |
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| 01:43 | , which is kind of weird because I hear things, I don't think |
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| 01:46 | movement. And when I think of sense of balance or equilibrium, I |
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| 01:50 | think about movement. But the types receptors that involve the hair cell is |
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| 01:54 | plays a role in both of these , right? And so kind of |
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| 01:57 | starting point here is going to be the hair cell. And so the |
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| 02:02 | cell, this is uh an electron showing you and it looks like a |
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| 02:05 | of asparagus kind of stacked up against . Uh But the cartoon I think |
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| 02:11 | a better job and you can see that what you have is you have |
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| 02:14 | type of specializations called asteria. They're connected to each other and they're kind |
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| 02:20 | shaped in a V formation. And the front end is a kinocilium and |
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| 02:24 | kinocilium is like the head stereocilium. what we can do is we can |
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| 02:29 | the stereocilium one way or the other change the degree of channels that are |
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| 02:36 | in this particular receptor, which will have the cell either hyper polarized or |
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| 02:41 | to give us a give us a of movement relative to those hair |
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| 02:46 | So if we push the hair cells way or push the sylla one way |
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| 02:50 | the still the other way, and are not SIA in the sense of |
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| 02:54 | what you see on bacterium or on esophagus or whatnot. This is a |
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| 02:58 | that you see specifically in these cells gives you a sense of detection |
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| 03:03 | of movement of something. All Now, the two types of things |
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| 03:08 | going to be looking at. So see up here vesti and auditory |
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| 03:11 | what we're saying is I am detecting something that is responsible for my |
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| 03:17 | right? So understanding whether or not moving or not moving is really kind |
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| 03:23 | what we're saying here, right? so this is going to be |
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| 03:27 | equilibrium is measured or, or identified something called the vestibular apparatus within the |
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| 03:34 | of the ear structures, right? then the other is what you're more |
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| 03:38 | with is audition, which is And so this is going to be |
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| 03:41 | in another structure inside the ear called cochlea, all right. And so |
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| 03:46 | we can do with this is we detect the things and how things are |
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| 03:50 | and where I'm moving relative to other as well as knowing where sounds are |
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| 03:56 | from their direction and you know, things about this, about the |
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| 04:02 | it allows us to communicate frankly. this is our starting point. And |
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| 04:07 | I want to do is I want first deal with this question of uh |
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| 04:10 | transduction. All right, because it unique to the ear. It is |
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| 04:15 | the same type of mechanical uh detection we detect in the skin. And |
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| 04:20 | as I mentioned already, we have Stoia they have on them, they |
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| 04:24 | a series of of potassium channels and going into way too much detail, |
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| 04:30 | weird about the ear is that the fluid that surrounds the structures of |
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| 04:35 | ear and the fluid inside the cells the air are kind of flip |
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| 04:38 | So what's happening is is potassium flows the cells and when that happens, |
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| 04:43 | depolarizes. So it's backwards to what been learning previously where it's like, |
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| 04:47 | when sodium moves in the cell, depolarizing. So it's kind of flip |
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| 04:51 | in the ear. All right. so these channels are usually slightly open |
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| 04:56 | of the way that they're arranged. so there's a slight opening, but |
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| 05:00 | you bend the stereo cella towards the what's going to happen is is you're |
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| 05:06 | to open up more of these they actually are causing the channels to |
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| 05:11 | up physically. And that allows more to flow in. So you get |
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| 05:14 | depolarization. But if you bend the cilia, the opposite direction, in |
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| 05:19 | words, away from the kinocilium, you can see how they're all connected |
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| 05:22 | each other. What that does is causes the channels to close. So |
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| 05:27 | movement of the, of these hairs or the stereo cella on top of |
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| 05:31 | hair cells are causing the channels themselves open and close. It's the mechanical |
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| 05:36 | manipulation of the channels. All So these are gonna be found both |
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| 05:42 | the vestibular apparatus and in the they are the things that are responsible |
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| 05:46 | both of these two things that we're be talking about. So how they |
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| 05:51 | is differently in with regard to equilibrium with regard to audition. All |
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| 05:57 | So we're kind of jumping around because when I would give a talk about |
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| 06:02 | , I'd talk about, let's talk all the parts of the ear and |
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| 06:05 | not doing that. This is not anatomy class. So you're still kind |
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| 06:09 | responsible for knowing the parts of the . But what I wanna do is |
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| 06:13 | want to jump deep into the ear what is called the inner ear. |
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| 06:16 | right. So we have an outer , we have a middle ear, |
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| 06:19 | have an inner ear and this is we're spending our time and this structure |
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| 06:22 | here. OK. The inner ear an actual bone. It's a structure |
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| 06:28 | independent of the temporal bone and it in there and it creates this little |
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| 06:32 | looking thing. If you, if say that once and you look at |
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| 06:35 | , you're like, yeah, it's alien and it's stuck in my |
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| 06:38 | All right. And so this bony , which is what is represented by |
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| 06:43 | green is kind of the outside. inside the bony part, we have |
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| 06:47 | tissue, you know, a soft structure, what we refer to as |
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| 06:51 | membranous labyrinth. So on the we have the bony labyrinth on the |
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| 06:54 | , we have this tissue and it's the tissue, this this membranous labyrinth |
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| 07:00 | we're going to be doing the detecting both sound and for equilibrium. |
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| 07:08 | the structures that are going to be on the outside from the bony parts |
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| 07:13 | the cochlea. You can see the right there. Here it is. |
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| 07:16 | do you think cochlea means without any knowledge of Latin or, or |
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| 07:21 | ? I don't know which word it from. What do you think it |
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| 07:23 | looking at this structure? Snail, is what we're looking for. It |
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| 07:28 | like a snail shell, doesn't So now it even gets more alien |
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| 07:32 | freaky because you look at the other it looks like a baby. All |
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| 07:37 | . But this other region, these things right here is the vestibular apparatus |
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| 07:43 | . So this structure hanging out here on the side. So we got |
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| 07:47 | cochlea and we have the vestibular the two structures that make up the |
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| 07:51 | apparatus in the vestibule. So this the region that is considered to be |
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| 07:57 | vestibule. So right up there and you have the three semi circular canals |
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| 08:02 | the semi circular canals sit at three . We're just gonna keep our life |
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| 08:05 | and just say they're at the X Y and the Z plane. Is |
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| 08:08 | OK? Is that easy for you kind of comprehend that idea Xyz, |
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| 08:13 | ? They're not exactly XYZ, but you can get that. Now inside |
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| 08:19 | , we said there's this membranous labyrinth well. So the hair cells are |
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| 08:24 | within the membranous part. So you the hard part on the outside, |
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| 08:29 | a fluid inside that that fluid is the para limb. And then moving |
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| 08:34 | the membranous labyrinth is, is the . This is where we get the |
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| 08:37 | flop. All right. So it's not the same sort of fluid |
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| 08:42 | you'd expect everywhere else inside the we have the cochlear duct. We'll |
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| 08:47 | to that. When we talk about inside the vestibular apparatus, we have |
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| 08:52 | structures of interest. All right. notice we went from two structures of |
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| 08:57 | , the semi circular canals to three inside the vestibule. We have the |
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| 09:02 | saule, the uterus saccular are what termed otolith organs that will become important |
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| 09:07 | just a moment. All right, semicircular canals have the semi circular |
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| 09:14 | again, not quack, quack, like duct work. OK. And |
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| 09:18 | inside these where we're gonna be having hair cells. So if are you |
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| 09:22 | me in terms of the micro anatomy we're kind of dealing with? It's |
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| 09:28 | , a lot of this is I to kind of visualize it even though |
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| 09:30 | are terrible cartoons. So let's start the oli organs in the vestibule. |
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| 09:35 | right, Their job is to look static equilibrium. In other words, |
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| 09:40 | detecting a linear acceleration. Have you ever been to um an amusement park |
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| 09:47 | has a uh large tower dungeon drop , right? If you haven't done |
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| 09:52 | , have you ever been in a with an elevator? All right. |
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| 09:55 | you ever felt yourself moving in an or when you got to the top |
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| 09:58 | the dungeon drop when they let you ? Did you notice that you were |
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| 10:01 | really, really fast? Right. what you're detecting is movement in the |
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| 10:06 | plane? So that would be an of static equilibrium. That sort of |
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| 10:10 | , linear acceleration. All right. other type. Have you ever been |
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| 10:15 | a car that's going fast? Are the reason it goes fast? |
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| 10:20 | good. That's, that's me as as I can get it. If |
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| 10:23 | could go faster than 90 miles an on the highway, I would, |
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| 10:27 | don't let me. Well, it's because other cars are in the |
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| 10:32 | Anyway. So if I press on gas and actually II I like to |
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| 10:38 | this story because it's stupid and because like to drag things out when I |
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| 10:43 | in high school, my buddy had Mustang GT. This was back when |
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| 10:47 | started making mustangs all over again. this is mid eighties. All |
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| 10:52 | So just nod and go. he's old. So dinosaurs. |
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| 10:57 | OK. And the claim to the Mustang GT was that it could go |
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| 11:02 | to 60 in like five seconds. we were really excited about this. |
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| 11:05 | we wanted to test it right We didn't do anything stupid. |
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| 11:08 | kind of, we always did stuff was stupid. But all we did |
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| 11:11 | he got, he wouldn't let me it. So he was like, |
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| 11:14 | right, I need you just to sure that there's nothing in the |
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| 11:18 | And so he looked at his watch he put his hand like this and |
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| 11:21 | said, ready go. And then went and I said, OK, |
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| 11:26 | been, you know, whatever. he's like how fast and I told |
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| 11:28 | how fast it was. But what of acceleration was that linear? |
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| 11:35 | OK. Can we time out for second? We're gonna be talking about |
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| 11:40 | very simple vectors, a vector in vertical plane and a vector in a |
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| 11:44 | plane. But if I'm moving as vector in say the horizontal plane do |
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| 11:48 | have, do I have a vertical to myself? I see one head |
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| 11:53 | . Yes. You're saying no. right. We got a debate |
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| 11:57 | One, yes, one, Is there when you're dealing with |
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| 12:01 | Is there always a vertical and horizontal ? Is there an X and A |
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| 12:05 | component? The answer is yes. answer is yes. Right. If |
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| 12:11 | moving in the X plane, do have a Y component? The answer |
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| 12:16 | yes. What is my Y component ? OK. When we're talking about |
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| 12:23 | , we're keeping things as simple as . OK. So I describe the |
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| 12:28 | and the sale. We're just saying moving this direction, I'm moving in |
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| 12:31 | direction. But when I go up hill like or in an airplane, |
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| 12:37 | utricle and saccular are going to be . They both detect that kind of |
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| 12:42 | because they do have a slight component the other aspect. All right. |
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| 12:48 | the reason I mentioned this now is when we get to the semi circular |
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| 12:51 | , we're gonna talk about linear or sorry, uh uh acceleration along |
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| 12:56 | angle. So angular acceleration. All . And so I don't want you |
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| 13:00 | just think that we have one for and one for the other. But |
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| 13:04 | the purposes of the exam that should you all up, we have an |
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| 13:12 | and an angle. OK? To our lives simple. But I want |
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| 13:17 | to go on to your future knowing much more than what we're actually |
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| 13:23 | . OK. So within the otolith , we have this gel like gelatinous |
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| 13:29 | substance. It's called a macula. right, I'm gonna warn you. |
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| 13:33 | , we have a lot of things end with la in the vestibular |
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| 13:36 | Macula is the first one. The macula is basically like a tray |
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| 13:42 | jello. And what we're doing with tray of jello is we have the |
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| 13:46 | cells embedded in the tray of You can see up there, there's |
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| 13:50 | tray of jello. You can see hair cells with their little tiny kinocilium |
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| 13:53 | the stereocilium sticking up into that And then the other thing that we |
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| 13:59 | in the jello is we're going to little tiny banana slices and grape slices |
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| 14:02 | like grandma used to do. Did grandma ever make you jealous like |
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| 14:10 | What did I say on Tuesday? need to get out more? All |
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| 14:17 | . OK. You didn't get fruit your jello if I put fruit in |
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| 14:22 | jello, what I, what am giving to my jello? I'm giving |
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| 14:26 | mass, aren't I? So if start jiggling my jello, my jello |
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| 14:31 | jiggle whether or not it has fruit it or not, right? But |
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| 14:35 | I have mass in it, what's happen with that jello? It's gonna |
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| 14:39 | a lot more, isn't it? going to have mass and therefore when |
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| 14:42 | starts movement, it's going to have that it needs to overcome. All |
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| 14:48 | . So in the macula, the are the otoliths, right? These |
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| 14:54 | calcium carbonate crystals embedded inside the And what this does is it gives |
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| 15:01 | macula mass. So when you accelerate , your um macula basically sits and |
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| 15:09 | it begins to move backwards, And so it's that mass that allows |
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| 15:14 | macula to start wiggling in the way it needs to, it bends the |
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| 15:21 | . All right, you guys lived Houston long enough. How many of |
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| 15:23 | have ever seen a yellow light? you could make it. And then |
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| 15:25 | the last minute said, no, mind slammed on your brakes. And |
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| 15:29 | you felt yourself decelerated? Right. that happening? That's the macula that |
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| 15:34 | gone backwards and all of a sudden , you know, it kind of |
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| 15:36 | back up to normal after the inertia then slam on the brakes. Macula |
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| 15:40 | going to be in the other right. So the idea here is |
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| 15:45 | in our otolith organs, we have macula with otoliths in it. And |
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| 15:49 | otolith is what gives the macula mass that I can make the hair cells |
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| 15:54 | one way or the other other. , up here, I have something |
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| 15:57 | that is unique to this class. don't think I've ever seen it taught |
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| 16:01 | any other class except for at the levels is that if you look at |
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| 16:05 | macula and the way that the hair are actually arranged, they're not all |
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| 16:08 | in the same direction, they actually reversal lines. So both of our |
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| 16:13 | organs can actually detect movement because you hair cells that are bending one towards |
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| 16:19 | one away from this reversal line. it's a little bit more complex than |
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| 16:23 | I'm trying to describe is what I'm to get at. OK. |
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| 16:27 | the two structures I mentioned are the and the saccule. What we're gonna |
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| 16:31 | here is we're just gonna keep this , really simple with the utricle. |
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| 16:36 | stereo cell are in the vertical That means they're pointing this direction. |
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| 16:39 | means when they bend, you're bending way or you're bending that way. |
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| 16:43 | that means I am moving in the plane. OK. So the U |
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| 16:50 | detects horizontal acceleration or in English when got in that little Mustang GT and |
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| 16:57 | accelerated by slamming the gas and I myself go back into the chair. |
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| 17:02 | was the utricle that let me feel OK. With the saccule, this |
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| 17:08 | what is used to help me feel I'm climbing up or going down in |
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| 17:12 | elevator here, the macula sits in horizontal so that the hair cells are |
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| 17:20 | the horizontal plane. OK? So hair cells are facing this way in |
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| 17:27 | saccule, the hair cells are this . So if I'm in the dungeon |
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| 17:33 | and I'm accelerating towards the ground. hair cells go this way and |
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| 17:36 | if I'm in an elevator and I'm express elevator going up, my hair |
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| 17:39 | bend that way, they bend in vertical direction. So I'm detecting vertical |
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| 17:47 | . All right. Now again, has reversal. I'm not gonna ask |
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| 17:51 | about the reversal line. I I've never asked about the rev reversal |
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| 17:54 | . It's not important enough for this . The key thing here is to |
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| 17:59 | when I'm dealing with the vestibular horizontal acceleration, linear acceleration, vertical |
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| 18:08 | , just make sure you match them that you recognize that they have the |
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| 18:13 | carbonate crystals. OK? Yes, . Yeah, please do. |
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| 18:23 | So think of it like when you're the car, right? You're in |
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| 18:27 | car and you accelerate. Which way you get pushed backwards? So what's |
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| 18:30 | is is that your hair cells are when you go, the, |
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| 18:33 | the macula is sitting initially, but the inertia pulls it backwards. And |
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| 18:38 | the hair cells are being pulled this . And what they're doing is they're |
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| 18:42 | towards the knoy. So the knoll pointed this direction, right? And |
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| 18:47 | when you decelerated, it's the opposite , right? So far are you |
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| 18:53 | me? Got one K nodding two slightly nodding heads. Where did |
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| 19:02 | lose you? It's OK. You say I lost you. There's nothing |
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| 19:07 | with saying I didn't get it the time. So the idea here. |
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| 19:13 | in terms of direction, which way cares are bending, always bending towards |
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| 19:18 | knoy to open them, to detect , the um thing. So if |
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| 19:23 | going forward, the knoy have to pointing away so that the, the |
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| 19:29 | moves with that. All right, that in mind, let's switch over |
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| 19:35 | the semi circular canals. All semi circular canals. We said there |
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| 19:40 | three of them. All right, the semi circular canals, we have |
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| 19:45 | ducks. So we have this tube runs through the canal and at the |
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| 19:50 | of each of the, of the circular canals inside, we have |
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| 19:55 | we have a, well, we a large structure called an Aula. |
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| 19:58 | remember, I promise you a lot love names. So we have an |
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| 20:00 | . So it's just an Aula is an open space, right? It's |
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| 20:04 | that starts off then and gets fat spaced or, or empty. And |
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| 20:09 | the Aula where our duct work is , we can see that we have |
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| 20:14 | speed bump. All right. So our little cartoon, you can see |
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| 20:17 | speed bump right here. OK. here's the semicircular canal bump in the |
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| 20:23 | off. You go around around the , this speed bump is called the |
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| 20:29 | . So we have an aula and have a cupula and in the otolith |
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| 20:32 | , we have a macula. All . So there's a lot of |
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| 20:36 | So just make sure you put the in the right place right now. |
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| 20:41 | cupula is kind of like a It's not a macula, but it's |
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| 20:45 | of like one, right? You see in our little cupula, what |
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| 20:48 | we have? We have hair cells into it? Do you see the |
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| 20:50 | cells sticking into it? They're supposed be in there? Yeah. So |
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| 20:53 | you are. Should point there. is. So I was pointing that |
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| 20:59 | . It's this thing right here. here the hair cells are sticking in |
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| 21:02 | . All right. What it does have is it doesn't have any |
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| 21:05 | So there is no calcium carbonate crystals the semicircular canals. Instead what happens |
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| 21:12 | is when you move your head, ? You have this tube, you |
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| 21:16 | two that are going this way. one on each side, two that |
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| 21:19 | going this way and two that are that way or really like that. |
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| 21:23 | right, all the ampler are kind near each other. So whenever you |
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| 21:27 | your head, what happens is is create inertia again and that causes that |
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| 21:33 | inside this tube to kind of wait a second and then it spins with |
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| 21:37 | head, right? And when when you start moving your head, |
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| 21:42 | fluid that is has inertia basically causes copulas to bend under the pressure or |
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| 21:49 | movement of that of that fluid inside tube. So our one side is |
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| 21:54 | one way, the other side, going the, I mean, the |
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| 21:57 | is going this but, but you think in terms of the Kia they're |
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| 22:01 | so that you're detecting which side is to which side, right? So |
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| 22:05 | move this way, I'm bending, say I'm bending hair cells this way |
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| 22:09 | I'm bending the cupula this way this . But really what's happening is I'm |
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| 22:13 | up, cup, opening up the and, and closing on this |
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| 22:17 | So, on this side, it's , oh, you're moving this direction |
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| 22:21 | of that pattern of activity that's being . Yeah. Yeah. OK. |
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| 22:29 | in a different part. And we'll there in a second. The question |
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| 22:32 | water in my ear and I get things, all stuffy. Right. |
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| 22:35 | where you're gonna go with that. get there in about two minutes, |
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| 22:38 | minutes, 10 minutes, depending on much, I mean, actually, |
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| 22:44 | just looking at like two minutes So, what I'm detecting now is |
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| 22:49 | detecting angular rotation. All right. , let's put this into something I |
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| 22:54 | we talked about on Tuesday, the of the, uh, the, |
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| 23:00 | three ringed. Um uh, it's a, it's a giant human |
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| 23:07 | . All right. And if you've done it, you can go down |
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| 23:09 | the Natural Science Museum. Pay like bucks and they let you write in |
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| 23:13 | for like two minutes and then you to vomit or you can go down |
|
| 23:17 | , uh chema, you know, do that. A boardwalk again. |
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| 23:21 | some money after a couple of minutes up or you can do it at |
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| 23:25 | break where you drink a lot first then you go do it and then |
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| 23:28 | get to throw up more. I presume that no one likes to |
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| 23:33 | , but it's really cool. You in there and you got one circle |
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| 23:36 | this way, one circle starts going way and the third one goes the |
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| 23:40 | way. And so all three of make you do this. I know |
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| 23:44 | , that's how I felt too. right. Now what these three semicircular |
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| 23:49 | are doing? It allows you to the movement of your head in terms |
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| 23:54 | angular movement. All right. So example, me saying no, can |
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| 23:59 | feel my head going back and Can I, why don't you |
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| 24:05 | Can you feel your head doing Yeah. What about if you go |
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| 24:09 | way? Yeah, I remember I you, did you guys ever lie |
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| 24:14 | on a, remember? It says a merry go round, you can |
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| 24:20 | yourself spinning this way, make stuff up. Yeah. Thank so it's |
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| 24:32 | inner ear issue. If you ask , what is the issue? I |
|
| 24:38 | know. All right now, my , like I said, is a |
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| 24:41 | therapist. I think I've told you that before. Right. No, |
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| 24:44 | haven't. Ok. Well, my is a physical therapist. You |
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| 24:48 | something else about me. All One of the things they do to |
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| 24:52 | vertigo, physical therapists can treat vertigo that they'll actually, you know, |
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| 24:57 | you down and it will raise you really, really fast. And apparently |
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| 25:01 | it does is it helps to re or modify these structures. How |
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| 25:07 | it's more like voodoo than anything else my understanding because I asked her, |
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| 25:11 | said, well, what exactly are doing? And she's like, either |
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| 25:16 | haven't explained it or again, it's we're surprised this works. It's probably |
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| 25:19 | said, you know, we're gonna , we're gonna try this sometime we're |
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| 25:22 | see if we can make this person and then they reset it. But |
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| 25:28 | point of all this stuff is that you're able to detect motion, |
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| 25:34 | You can detect your own movement. think about when you run, |
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| 25:39 | If you're running in a circle, you feel yourself running in a |
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| 25:43 | Can you detect that movement? And what it's doing is it's telling |
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| 25:47 | brain about what kind of movement you're . And probably the motion sickness is |
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| 25:53 | , I'm just trying to pull pieces I remember. It's your eyes and |
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| 25:58 | inner ear not matching up, In terms of the information that it's |
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| 26:04 | . So that's what gets you, don't hear, get car sick when |
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| 26:06 | read like you're in the car and reading, you get car sick. |
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| 26:11 | , see, some of us don't how I said. Some of |
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| 26:13 | every one of my kids vomit. cannot understand this. But for me |
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| 26:18 | was like, I could read upside in a car and have no |
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| 26:21 | My kids, they even look down they're just like, oh, I'm |
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| 26:25 | be and then they throw it and still do. Yeah. Mhm |
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| 26:35 | it's considered angular because of the way the, that you're moving, the |
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| 26:39 | . Now you're doing the exact same I said, I said if you |
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| 26:42 | like, wait a second, what I'm nodding my head? Well, |
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| 26:44 | , there's not only angular mo movement , there's also linear movement. And |
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| 26:48 | remember what I said is we're going back away from the complexity here and |
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| 26:52 | just trying to keep it simple, ? So there is a horizontal. |
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| 26:55 | when I look down so like, look, there's my feet. What |
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| 27:00 | I done is I've have angular acceleration my head turns along that line, |
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| 27:06 | ? But it's also, I've changed position on my head. And so |
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| 27:10 | those olis are gonna be pulled with to the utricle is gonna be pulled |
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| 27:15 | . And so I can detect I'm down on the test. What do |
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| 27:21 | think? I'm going to ask It's gonna, what, what do |
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| 27:23 | think the answer would be? What is playing the major role in detecting |
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| 27:27 | looking down semi circular canals. If you're in a car going |
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| 27:32 | which ones, which one is predominantly you your movement, if you're in |
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| 27:37 | elevator, which one is dominant All right. That's the way I |
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| 27:43 | you to learn it right now, you move on and go on to |
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| 27:47 | bigger and better things and they teach the right thing. Listen to those |
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| 27:52 | . They usually don't teach you much detail than that unless you're going into |
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| 27:55 | field. So, are we OK these? Do we understand this type |
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| 28:00 | detection that the, the thing that detecting is not the physical movement but |
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| 28:06 | movement of the fluid created by the of my head. So it's an |
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| 28:11 | mechanism of detecting movement of my That makes sense. I've seen a |
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| 28:18 | eyebrows doing this, your eyebrows weren't that. Just let you know, |
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| 28:29 | I go on or we want to ? Hearing? Yeah, hearing. |
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| 28:34 | . Now again, same thing, gonna be dealing with these types of |
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| 28:38 | cells right now. I want you be familiar with your ear anatomy. |
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| 28:44 | right. So we got the external , we have the middle ear. |
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| 28:48 | right. And you'll see as we through, I'm gonna list these things |
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| 28:51 | I need you kind of to apply as we go along. I don't |
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| 28:54 | to walk through all the anatomy because we do that, then we an |
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| 28:58 | 20 minutes talking about stuff, you get one question on. All |
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| 29:02 | But what I want to do is want to jump to the middle |
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| 29:04 | So sound travels from out here through outer ear. It's a sound |
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| 29:11 | that wave is going to hit the membrane and it's going to go and |
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| 29:16 | going to transfer to the inner ear the middle ear. And what we're |
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| 29:20 | with the middle ear, the middle at uh is the best to, |
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| 29:24 | describe it as an amplifier for for your inner ear. All |
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| 29:28 | And the reason we need an amplifier because it's filled with fluid. The |
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| 29:32 | ear is filled with fluid. All . Have you ever gone under water |
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| 29:36 | tried to talk to somebody? Do you guys swim? Right. |
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| 29:43 | you're telling me when you're like in school or maybe even junior high? |
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| 29:47 | there was that cute I'm looking at there's mostly women in here. I'm |
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| 29:49 | gonna, there's that cute guy in and you guys give googly eyes and |
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| 29:52 | say you're cute. You're so I think you're pretty. I think |
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| 29:56 | handsome. Did you not do that ? What do you guys need to |
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| 30:02 | ? Get out more? OK. whole point of the swimming pool is |
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| 30:07 | flirt with less clothes on. and we live in the Deep South |
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| 30:20 | on man. All right. we got the timpani membrane. All |
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| 30:24 | . And the timpani membrane vibrates at same frequency as the sound waves that |
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| 30:29 | coming in. And what that timpani is associated with are these three |
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| 30:34 | the malis, the incus and the you probably learned when you were |
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| 30:37 | right? It's the hammer, the and the stirrup name for what they |
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| 30:41 | of look like. So we go Incata. And what happens is, |
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| 30:45 | the sound wave is actually amplified. doesn't mean we change its frequency, |
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| 30:50 | just make it bigger. And so that is doing is it's uh presenting |
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| 30:56 | sound wave in a much more powerful to the next structure. This next |
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| 31:02 | is a membrane called the oval And the oval window is the membrane |
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| 31:06 | separates the middle from the inner All right. And this uh this |
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| 31:12 | duct work is basically going to go and around it and it's going to |
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| 31:15 | back the other direction and here is it's going to empty out, that's |
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| 31:19 | round window. And so the sound that energy that's going here is going |
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| 31:24 | work its way all the way around ultimately end up at that round |
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| 31:28 | And it's kind of like those little toys. You remember the stress |
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| 31:31 | you squeeze them and the little eyes out. Basically, that's what you're |
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| 31:34 | . It's like squeezing the end of balloon and the other end of the |
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| 31:37 | kind, right. That it absorbs energy. So the energy is |
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| 31:41 | It's not gonna keep ricocheting back and in the tube. All right. |
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| 31:45 | , we haven't even gotten there We're just looking at structure. Answer |
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| 31:48 | question. All right. When my get all stuffed up, what's going |
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| 31:52 | ? Well, that really has to with the Eustachian tube. The eus |
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| 31:55 | connects the middle ear so you can it right there and it comes down |
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| 31:59 | opens up into the back of your . All right. And so when |
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| 32:03 | ears get all cloy and hard, happens? It's hard to hear |
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| 32:08 | isn't it? And the reason for is because the pressure has built up |
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| 32:12 | the middle ear. And so the doesn't move quite as well because the |
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| 32:18 | is preventing the vibration of those So what do we do? We |
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| 32:25 | our ears good. That's one way can do it, you can go |
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| 32:28 | blow and that creates pressure that opens the tube so that you get equilibrate |
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| 32:35 | here, done any sort of um I was gonna say Timy, but |
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| 32:41 | not what it's just percussion work. , any percussionists. No. So |
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| 32:46 | you bang on a drum on one , you get a nice sound, |
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| 32:49 | ? But if you put your hand the other side, on the other |
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| 32:52 | of that membrane and start beating on drum. What does it sound |
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| 32:55 | Look, look, look, you don't get the vibrations. So |
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| 32:58 | kind of what the pressure is doing that's why everything sounds so stuffy. |
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| 33:04 | . Now, were you asking about in my ear when I go |
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| 33:08 | So, what's going on there? , you have wax in your ear |
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| 33:11 | so water kind of builds up there prevents the sound waves from causing tipa |
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| 33:17 | . And then of course, the is even worse because it, it |
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| 33:20 | water, right. So it gets there. And so you have to |
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| 33:23 | there and put a cotton ball on ear. Q tip. Small cricket |
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| 33:30 | teasing. Don't put crickets in the . All right. So that's what |
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| 33:35 | to it allows you to equalize the . Um, you can blow your |
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| 33:39 | like that, you can go like and if you're really, really |
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| 33:43 | you can suck on something. So you're ever flying and you have |
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| 33:46 | like for those, you are going interviews and stuff and you're flying places |
|
| 33:49 | you need to put up, make kids shut up, travel with dumb |
|
| 33:54 | . You know, those little tiny give them to the parents, especially |
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| 33:58 | they're young parents say this is for kid. And if they're like, |
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| 34:02 | , my child is sugar free and like the rest of us want you |
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| 34:04 | have this kid sucking on that The kid will suck on it because |
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| 34:08 | sugar and it will cause your ears pop and they'll be happy. |
|
| 34:13 | All right. That's, that's my advice. All right. So here |
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| 34:18 | are, we're in a Cochlea. remember Ar Cochlea is the snails shelf |
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| 34:23 | thing. If you look at it the side, you can see it's |
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| 34:26 | a spiral that goes up. And this is what you're looking at, |
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| 34:30 | goes up and then it comes and . And really what we have is |
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| 34:34 | have a couple of different tubes. have really doing a really poor job |
|
| 34:38 | you here. So, what we is we have an upper tube that |
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| 34:43 | all the way up, reaches the , the apex turns on itself and |
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| 34:47 | comes all the way back down and the other half of it. All |
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| 34:50 | . So we have the uh the duct and we have the timpani |
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| 34:57 | Those are the two names for So on the way up, it's |
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| 35:00 | vestibular duct turns on itself, comes down and it becomes the timpani duct |
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| 35:05 | between them. This is the ness uh labyrinth, the membranous labyrinth forms |
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| 35:13 | is called the cochlear duct and this where we're going to spend our |
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| 35:19 | Ok. So the way you can about it is sound goes in via |
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| 35:24 | oval window, it travels up through vestibular duct goes all the way up |
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| 35:29 | round, round up and then turns on itself and comes back down this |
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| 35:33 | and in between. So the space this is trying to represent there is |
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| 35:37 | cochlear duct, this is a side of what you're looking at of all |
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| 35:42 | . And here it is us focus in. So just to make sure |
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| 35:47 | understand where we are oval windows over , sound wave goes this way travels |
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| 35:53 | the way up, travels all the back down. And right here would |
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| 35:56 | the round window. So you can we have a couple of membranes in |
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| 36:02 | way. All right, the floor the vestibular duct is called the vestibular |
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| 36:09 | , not too hard, the roof the timpani membrane. So that's the |
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| 36:14 | , right vestibular membrane, the roof this duct is the basilar membrane. |
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| 36:21 | you can think of it. The way if I'm looking at the cochlear |
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| 36:24 | , I have the vestibular membrane as roof. I have the basal membrane |
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| 36:28 | my floor. And the work that gonna be looking at is gonna be |
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| 36:31 | place here in the cochlear duct. , the structure of interest is called |
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| 36:37 | organ of corti named after the guy discovered, discovered it here. What |
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| 36:43 | have inside the middle of the uh cochlear duct is the tectal membrane. |
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| 36:52 | , there's all these membranes. So got a Basler membrane, I've got |
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| 36:56 | uh sorry vestibular membrane. I have Basler membrane in between that makes the |
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| 37:01 | so like that. Sorry here, better. So I have a basal |
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| 37:05 | , I have a T orial And over here I have the vestibular |
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| 37:09 | . Now, why I'm going through this stuff is because all these structures |
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| 37:13 | working together to allow us to detect . OK. And what we're doing |
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| 37:19 | we're sending a sound wave up through uh this uh vestibular duct and it's |
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| 37:25 | gonna make it all the way. right, sound waves have to them |
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| 37:32 | frequency, right? And an amplitude is a distance, isn't it? |
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| 37:41 | ? It's a wavelength and so a is gonna travel whatever that distance happens |
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| 37:47 | be, right? So high notes short wavelengths, deep notes have long |
|
| 37:57 | . All right, so far you're me kind of sort of. So |
|
| 38:02 | go up here for a second. remember when we looked at light wave |
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| 38:07 | , had this really weird, did bother to go look on Wikipedia at |
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| 38:10 | picture? Was it there? No looked? OK. I'm telling |
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| 38:16 | learn something new, just go and . All right, you don't have |
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| 38:19 | . But, but look here, is the type of wavelengths that we |
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| 38:24 | think about, right? We think a wavelength as basically just going in |
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| 38:29 | direction. If I had a rope started snapping the rope, you'd be |
|
| 38:31 | , yeah, that's a wave. that's what I'm used to seeing it's |
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| 38:34 | a cosine or a sign or All right. So the frequency is |
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| 38:39 | wavelength, the intensity is the So nothing new there. And what |
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| 38:45 | want to do is hearing is detecting frequencies. So how do we go |
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| 38:51 | doing that? And I think this is better than the ones that we've |
|
| 38:54 | looking at. So in this what we've done is we've taken this |
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| 38:58 | that wound all the way up, on itself and wound all the way |
|
| 39:02 | . All right. And what we is we unwound it. And so |
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| 39:05 | can see here here's the oval there's a round window, there's the |
|
| 39:09 | duct that goes up, turns on comes back around as the Tian duck |
|
| 39:13 | far are you with me? You see in between, what do we |
|
| 39:16 | , what do we call that cochlear ? And then part of the cochlear |
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| 39:22 | is the organ that is we use hearing is called the organ of cord |
|
| 39:25 | the organ of corti. It's this that has the hair cells. The |
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| 39:29 | cells are gonna be detecting the movement fluid inside the organ of corti. |
|
| 39:35 | , if you look at this, the movement of the water or the |
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| 39:40 | here ever find its way into the in the middle? What, what |
|
| 39:49 | between those two, those two I'll go back to the picture. |
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| 39:55 | stands between these two ducks a Thank you. If you don't have |
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| 39:59 | know the name right now for the , you better figure it out. |
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| 40:02 | right, it's a vestibular membrane. there's no way that fluid from here |
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| 40:06 | get into there. Would you agree me on that? Just say |
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| 40:08 | of course. It's like a can fluid move from here to there |
|
| 40:12 | vice versa. What do you No, they're in the way. |
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| 40:16 | what's going to happen here is that we begin vibrating the timpani membrane, |
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| 40:21 | gets amplified, moves to the oval causes it to vibrate at a specific |
|
| 40:29 | . And that wavelength will then travel the length of the scala vestibule until |
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| 40:36 | reaches the point where it goes up then comes down onto the vestibular |
|
| 40:43 | So high notes are going to only a short distance long notes would travel |
|
| 40:49 | further. All right, you're looking this picture and I know you're looking |
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| 40:53 | this picture because the same way I at it when I was sitting |
|
| 40:56 | right? Or the first time you this, but the cloud, it's |
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| 40:59 | you a bunch of squiggly lines and of a sudden magically, it it |
|
| 41:02 | the membrane to vibrate at a certain . Uh The wavelength is the length |
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| 41:07 | which it goes up and comes back . So this artist screwed this |
|
| 41:12 | What he should have done is said is the wavelength that comes up and |
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| 41:16 | goes down or it comes up and goes down or whatever the length happens |
|
| 41:21 | be. Instead of drawing a bunch lines to say, somehow it magically |
|
| 41:25 | where it needs to go. Does make sense? So short wavelengths are |
|
| 41:29 | to be detected over here, long are going to be detected over |
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| 41:34 | Why? Because the vestibular membrane when wavelength comes and hits, it's going |
|
| 41:40 | cause the vestibular membrane to dip, ? Have you ever been in a |
|
| 41:51 | ? Every woman should be nodding their because that's where you spend 98% of |
|
| 41:55 | life. It's like I need to . I'm going into a bathtub, |
|
| 42:00 | ? All the guys are sitting there , I'm not allowed in the bathtub |
|
| 42:04 | . And all the guys know why not, not allowed in the bathtub |
|
| 42:08 | at the age of 10, when was probably your last bath, you |
|
| 42:12 | in the bathtub and you started doing , started rocking back and forth, |
|
| 42:16 | ? You remember that? You're laughing it happened, right? You start |
|
| 42:20 | back and forth and you get that going and it's nice and beautiful. |
|
| 42:23 | all of a sudden you get that wave and it goes boom and all |
|
| 42:27 | water comes out, mom comes screaming going. There's all the water all |
|
| 42:30 | the floor. All right, that's of what's going on here is that |
|
| 42:34 | creating a wave that is gonna go and then gonna cause that membrane to |
|
| 42:42 | . And when it causes that membrane move the fluid inside the cochlear duct |
|
| 42:48 | , where can it go? It down to the Basler duct or the |
|
| 42:52 | membrane. And these two things begin in synchrony at that particular location. |
|
| 42:58 | , what sits in between those two membrane, basal membrane, the teoria |
|
| 43:05 | , tectal membrane is like a hard board. It doesn't move, it |
|
| 43:09 | straight out. See there it I'm gonna steal his arm for a |
|
| 43:21 | . I can't take it away from . But see if you put it |
|
| 43:24 | like this. Do you see how nice and stiff? It doesn't move |
|
| 43:27 | I'm on this side, if I'm this way? Do you see how |
|
| 43:30 | just sits there? Now, imagine have hair cells down here in the |
|
| 43:34 | membrane. And so what's happening is every time I'm going up, |
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| 43:38 | actually thinking I'm creating a movement of , not just up and down to |
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| 43:45 | these things to shake, but that goes in underneath that tectal membrane and |
|
| 43:51 | flow. And what do the hair do? They've been back and |
|
| 43:58 | So I'm detecting the fluid moving at particular location. So I have an |
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| 44:06 | hair cell that's sitting out there waving and forth. I have three rows |
|
| 44:10 | outer hair cells. Their job surprisingly not to detect sound, but to |
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| 44:17 | and modulate the degree of movement they're inside. You see how they show |
|
| 44:22 | , they're stuck up there. So they do is they're, they basically |
|
| 44:27 | and grab onto the tectal membrane. you can actually create greater flow or |
|
| 44:33 | flow as needed. And so what doing is you're detecting sound here. |
|
| 44:41 | , does this actually detect the Now, what it's doing is you're |
|
| 44:46 | at a very specific location. This actually I think putting it all |
|
| 44:54 | this is where I want to talk . So here again, we have |
|
| 44:59 | picture you can see here is a unwound. You all agree with |
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| 45:05 | You can see up here that would the vestibular, well, the vestibular |
|
| 45:09 | would be on the top. The the timpani. I said Veste |
|
| 45:14 | excuse me, the uh the vestibular is on the top. The timpani |
|
| 45:18 | is on the bottom in the middle be the cochlear duct. And you |
|
| 45:21 | see here this is the basilar Notice one of the things that it |
|
| 45:25 | , it gets wider and wider and . So it makes it harder and |
|
| 45:28 | to vibrate, the closer you get the windows. And what this is |
|
| 45:32 | to show you is look when I movement, that wave comes up and |
|
| 45:36 | that membrane causing the basil or the membrane to vibrate, which then travels |
|
| 45:42 | the cochlear duct travels through and causes basal membrane that movement of the fluid |
|
| 45:47 | there is going to be detected just this point. Nowhere else I see |
|
| 45:55 | , look, anyone here play Yeah. If I hit a key |
|
| 46:00 | at this end, what kind of do I make? Low note or |
|
| 46:06 | note, low notes? If I'm here at this end, what do |
|
| 46:09 | make high notes? So if I picked up the keys and moved them |
|
| 46:14 | , would it change? No, inside the internals of the piano is |
|
| 46:21 | a big giant harp with hammers on , right? And so what I'm |
|
| 46:26 | is no matter what, it's always notes over here, no matter |
|
| 46:30 | it's always low notes over here. that this is what this is |
|
| 46:33 | It's saying, oh, I am hair cell located at this location. |
|
| 46:37 | I get stimulated, that means it a high note. Oh, |
|
| 46:42 | what about right over here? that's somewhere in the middle. What |
|
| 46:45 | over here? Well, this is White Land. You guys know who |
|
| 46:49 | White is, right? If you type it in youtube, Barry |
|
| 46:55 | right? You'll learn, OK. notes, medium low notes. And |
|
| 47:02 | your brain knows which notes it's which pitches its hearing because the signals |
|
| 47:09 | from the hair cells down through the nerve travel to the brain and tell |
|
| 47:15 | , hey, um this area got . Oh, you got stimulated. |
|
| 47:20 | . OK. So that means it's pitch. Now, here's the other |
|
| 47:26 | thing or cool thing if you think it when I talk, do, |
|
| 47:30 | I producing a pure note? What you think? Thank you. I'm |
|
| 47:35 | that the three people that looked at and went like this. Uh It's |
|
| 47:38 | a pure note. I have timber my, to my voice, don't |
|
| 47:42 | ? My voice is different than your and your voice is different than my |
|
| 47:45 | . And that's the result of that's . So there's different vibrations that are |
|
| 47:50 | . I've got different sized sinuses. got a big old larynx where some |
|
| 47:55 | you don't. And so I create unique sounding voice that produces multiple pitches |
|
| 48:01 | just like you do. And so sound waves are all traveling simultaneously at |
|
| 48:08 | speed of sound and hitting all those parts simultaneously. And those sounds are |
|
| 48:16 | the cochlear duct and specifically the organ corti at very specific locations. And |
|
| 48:21 | all that information is being sent up the cochlear nerves and basically saying, |
|
| 48:28 | , these are the things that you're and this is what puts all those |
|
| 48:32 | together so that you can hear and all those different sounds. But we |
|
| 48:39 | a wave, right? And this the last thing I want to mention |
|
| 48:43 | , we started a wave. They the vestibular duct or sorry, the |
|
| 48:48 | membrane to move, which caused the membrane to move and that wave has |
|
| 48:53 | go someplace if it bounced around, you'd hear is mud, right? |
|
| 49:01 | what happens is, is that there's direction that it goes. So it |
|
| 49:05 | in through the oval down through the through the basal membrane. And that |
|
| 49:10 | continues back to the round window and dissipated there. So in other |
|
| 49:17 | the way you can kind of think it just coming back over here, |
|
| 49:22 | sound wave comes in, finds a goes out, comes in, finds |
|
| 49:28 | shortcut goes out, it doesn't go the way around, but the energy |
|
| 49:33 | absorbed. Does this make sense or I just kind of talk way above |
|
| 49:39 | heads? Because I've given this talk times in the last couple of |
|
| 49:47 | Hm Well, so, so I what you're asking, but let me |
|
| 49:54 | of, so you're, you're asking does it know? It can't |
|
| 49:57 | All right, but it has a , all sound has characteristic, it |
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| 50:02 | a pitch or frequency, right? let me just go back, |
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| 50:06 | So frequency is the wave length, ? You ever wonder why you guys |
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| 50:11 | to take a physics class? You're , why do I have to know |
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| 50:16 | man? I mean, I'm a or kind of like a biologist. |
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| 50:20 | , the reason is, is because of the things we do are dependent |
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| 50:24 | physics. And so physics is basically , look, I have a wave |
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| 50:29 | has a specific characteristic. What is wavelength? My wavelength is here to |
|
| 50:36 | right there. I think that's right to there. I may be |
|
| 50:40 | It might be there to there. been a while. Right. But |
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| 50:43 | idea is that it has a fixed and that wavelength because of that fixed |
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| 50:47 | can only travel a fixed distance. . It's not gonna bounce around |
|
| 50:54 | Sorry, because it can't, it only go in and through if it's |
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| 51:01 | it goes in and further and if really long, it goes all the |
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| 51:04 | further. All right. So the you can ask is, well, |
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| 51:08 | you know there are sounds that I hear. There are ranges that dogs |
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| 51:12 | hear and there are whale ranges that can hear that I can't hear. |
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| 51:15 | is it that I hear? because our basilar membrane, our organ |
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| 51:19 | corti is fixed to a particular pitch the high pitch that we have to |
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| 51:25 | low pitch that we have. But have a basal membrane that have a |
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| 51:29 | for a much higher pitch. Whales a basal membrane that detects a much |
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| 51:35 | pitch. So it's not a length . It's how is it tuned and |
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| 51:41 | has to do with the thickness of membrane and all sorts of other fun |
|
| 51:45 | that we're not talking about? And then yeah. OK. |
|
| 51:55 | All right. Before what's up before go further? How did it get |
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| 51:58 | the old window? So don't, I'd say is don't neglect that. |
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| 52:03 | right, I'm not, I'm not at you, right? But we |
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| 52:06 | to remember sound comes in via the through the timpani membrane brain through the |
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| 52:12 | inca sta where we get amplification. You guys ever play the game mouse |
|
| 52:18 | ? Yeah, where you have to the Rube Goldberg machine and play the |
|
| 52:21 | . No one ever played the You just built the stupid thing and |
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| 52:23 | put the marble in, see if can catch the mouse at the |
|
| 52:26 | right? But it's the same sort thing. It's think of this as |
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| 52:28 | Rube Goldberg. Uh My, my is to hear. So I have |
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| 52:32 | start from way over here. So , don't forget the middle part. |
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| 52:36 | now you're at the oval window, here, we'll go here. So |
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| 52:46 | you're at the oval window, oval vibrates at the same frequency as the |
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| 52:51 | membrane. We have a certain So that frequency is gonna go vestibular |
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| 52:59 | for whatever. However, whatever the happens to be, you guys still |
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| 53:03 | as she goes. OK. So goes to the Vestibular membrane Council. |
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| 53:12 | it Yeah, so it doesn't cause tectal membrane to move, it causes |
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| 53:16 | Basler membrane to move. That's easy remember because it's the basement, |
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| 53:20 | So I'm going from the roof to uh to the floor causes the Basler |
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| 53:24 | to move. And if we just everything else for a second, the |
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| 53:26 | wave continues out through the round But let's go back and then the |
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| 53:30 | of court, what's happening, fluids because of the movement of the vestibular |
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| 53:35 | and the basal membrane and then that is detected by. You. Got |
|
| 53:43 | . Yes. Mhm No. You're a really good question. So what |
|
| 53:56 | when it's left for me? You hear me, can you? But |
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| 54:01 | you hear me now? Sorry, . Um notice, I mean, |
|
| 54:07 | would sing but it would be like wounded pterodactyl, right? So if |
|
| 54:12 | went, you know, and you , I can, if I can |
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| 54:15 | that note, it doesn't matter if soft or loud, that's amplitude. |
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| 54:22 | the amplitude is the amount of energy into it. So it hits the |
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| 54:25 | spot but it causes much more So you get more action potentials which |
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| 54:30 | up to the brain and say, by the way, um we're being |
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| 54:33 | here for that note, but we're a lot of that. So that's |
|
| 54:38 | the loudness comes from. All So amplitude is measured in decibels pitch |
|
| 54:44 | measured in hurts because it hurts. on notice. But that's, |
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| 54:51 | that's the difference. So yeah, . So it moves to the |
|
| 55:01 | So, so here you get So you imagine a louder sound would |
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| 55:06 | the same frequency of vibration, but would cause more vigorous vibration. All |
|
| 55:12 | . Ever been to a concert. . Ever been right there in the |
|
| 55:17 | row. Right. Marshall Stack, in front of you screaming. Bring |
|
| 55:22 | the band. They come out first . Wow. And you're like, |
|
| 55:27 | then after about a minute or it's like, all right, this |
|
| 55:30 | too bad. Ok. Well, reason it's not too bad is because |
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| 55:36 | amplifiers are still being amplified because of vibration. But we have muscles inside |
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| 55:42 | middle ear that clamp around them to them from moving as vigorously as they |
|
| 55:48 | . All right, the difference is not as fast as they should be |
|
| 55:52 | could be, which is why sounds loud and then it takes a little |
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| 55:56 | of time for us to adjust to . I'm just put, adjust to |
|
| 55:59 | . All right. Yes, Does that mean it is? |
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| 56:12 | So I think this is a I used to do it a little |
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| 56:16 | more. We spend more time talking the outer hair cell. But really |
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| 56:20 | idea here is as the fluid comes , basically, it, it has |
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| 56:24 | ability to move in both directions, , both in and out of the |
|
| 56:28 | , right? But really what we're to do is we're just trying to |
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| 56:31 | this one cell. So the fluid flowing around as the membrane comes down |
|
| 56:38 | the membrane comes down, that actually a pole. So that fluid comes |
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| 56:41 | underneath the tect orial membrane. And when the membrane vibrates back up, |
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| 56:45 | pushes the fluid back out. So what you're detecting is that movement of |
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| 56:50 | fluid back and forth underneath the tect membrane as the basal membrane goes up |
|
| 56:54 | down. What the outer hair cell because of the presence of this |
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| 56:59 | Preston is that it stretches like a and it says, I don't like |
|
| 57:04 | stretched. And so the Preston molecule down and causes the outer hair cells |
|
| 57:08 | contract, which causes the tectal membrane be pulled in closer and near to |
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| 57:13 | basal membrane. So you get different of movement of the fluid underneath. |
|
| 57:19 | you can modulate how much fluid is through, which changes your perception, |
|
| 57:25 | ? Because you're detecting slightly differently, it's still it's there to create something |
|
| 57:31 | you can actually force the water to over or through. So that the |
|
| 57:36 | cells wiggle, that's, that's a scientific term right there. Wiggles, |
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| 57:42 | hair cells. Are we OK with now a little bit? So I |
|
| 57:49 | made it more complicated than I needed . But it's, it's an interesting |
|
| 57:54 | and, and the way I teach the A P is I just walk |
|
| 57:57 | it just like I did you start the pea or the oracle go through |
|
| 58:02 | um the auditory me or, and , you not gonna have to know |
|
| 58:07 | but just like, OK, there's , tube, tube tian membrane, |
|
| 58:12 | ear and I just kind of walk and just, just build it as |
|
| 58:15 | go along. And if you can it out, step by step, |
|
| 58:18 | only like five steps was they would up with five steps or six |
|
| 58:25 | Six. Ok. It's not that . It just sounds like there's many |
|
| 58:30 | you get lost. What do you and dried out? How bad are |
|
| 58:37 | doing, man? I'm slow. just a slow person because I get |
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| 58:41 | about this stuff when I talk. right. 20 minutes, hopefully to |
|
| 58:48 | the rest of the stuff. All . So what we want to do |
|
| 58:51 | we go from C circuits to um reflexes and ultimately to neural maps is |
|
| 58:57 | kind of the goal here. So circuit simply is an interconnect, an |
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| 59:02 | network of neurons. And we're typically about local circuits. We don't want |
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| 59:07 | talk about the large circuits that this they're too complex for, for us |
|
| 59:12 | this class and really just in they're pretty, pretty complex. So |
|
| 59:16 | we do is when we look at local circuit, we can just break |
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| 59:19 | down into three parts. It has input and output and it has a |
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| 59:22 | unit, right? Some sort of neuron that's responsible for integrating |
|
| 59:28 | all right. And so we just some really simple examples that you can |
|
| 59:32 | here, right. So this would an example of a local circuit occurring |
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| 59:37 | the spinal cord. And this is of where we're going to be spending |
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| 59:39 | time because we're going to talk about . And this is a good example |
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| 59:42 | a reflex, right? We have that goes in. That's the |
|
| 59:46 | the sample that you're seeing in the is for an A or a sensory |
|
| 59:51 | moving in. But that's not the source, I mean, you can |
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| 59:54 | descending fibers coming down, right? could have uh stuff from other areas |
|
| 60:00 | that spinal cord, either above or or next to. So the input |
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| 60:05 | particularly important. Just understand information has come in from some place. All |
|
| 60:10 | . And then we're going to have sort of inter neurons usually involved. |
|
| 60:14 | can be excitatory nature or inhibitory in for the network. And then what |
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| 60:19 | have is after, after you determine the response should be, then you're |
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| 60:23 | to have some sort of output. in this particular case, it's going |
|
| 60:26 | be a motor neuron. So we a sensory neuron going in inter neurons |
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| 60:30 | process and then we have um motor moving out. And what you can |
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| 60:35 | here also in, in this particular is uh uh basically uh a type |
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| 60:42 | , of a um this is sad my brain just, just shuts down |
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| 60:49 | in the middle of class um the of input I'm looking or the type |
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| 60:52 | word I'm looking for here is the of circuits that are antagonistic. Thank |
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| 60:56 | . So we, we can see is that's antagonistic. So where we |
|
| 60:59 | an input coming in, one might turn being turned on, whereas the |
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| 61:04 | one is turning off so that you have basically like when you're trying to |
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| 61:08 | , say a muscle, this muscle the one that is being activated, |
|
| 61:12 | you want to turn off this muscle that you can cause your arm to |
|
| 61:17 | . All right. So that would and they, they're antagonistic movements. |
|
| 61:20 | both of them contract at the same , your arm wouldn't move. So |
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| 61:24 | idea is, oh I can't have is the idea. This is another |
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| 61:30 | of a local circuit. Again, is going to a cortex. So |
|
| 61:33 | can see here the six layers of cortex. So where is your input |
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| 61:36 | from? It could be an a fiber, it could be a relay |
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| 61:40 | from from another area or it could be an adjacent local area that's sending |
|
| 61:45 | fibers. So again, input doesn't , but it's coming into the |
|
| 61:49 | you're going to see inter neurons that going to be processing. So this |
|
| 61:52 | trying show you the inter neurons where in the pluses and minuses. Once |
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| 61:55 | information is processed, then information is sent outward via projection fibers to wherever |
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| 62:00 | going, whether it be to another of the nervous system, like in |
|
| 62:03 | central nervous system or sorry, the or say to one of the central |
|
| 62:08 | or maybe even down to the spinal . But the idea is the information |
|
| 62:13 | being sent away from that particular So the organization is not particularly |
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| 62:18 | it's input processing output and just how define those things. Yeah, it's |
|
| 62:27 | within a very, very small right? So the idea is like |
|
| 62:31 | we look at this one, I this is easier to visualize or understand |
|
| 62:34 | that because this, this is the and it's like, OK, if |
|
| 62:38 | understand my neuro anatomy, then I can see this, but most |
|
| 62:41 | us haven't done a neuro anatomy And so this kind of says, |
|
| 62:46 | just in this one little location, do I have? I've got everything |
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| 62:49 | need input in input or exp um out and then I've got something to |
|
| 62:55 | right there. So everything that you is there, you don't need to |
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| 63:00 | things off. Like I don't to China, you know, to |
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| 63:05 | processed and sent back, we're gonna back to that picture. In |
|
| 63:13 | that picture of the reflex really kind defined everything that we need to know |
|
| 63:17 | the nervous system. And we're going start here with the reflex. And |
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| 63:21 | you don't know, a reflex is rapid preprogrammed, meaning you'll always get |
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| 63:26 | same output. It always does this , very quickly. It's an involuntary |
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| 63:32 | to some sort of stimulus. All . And so here's just two examples |
|
| 63:36 | you guys all done. The knee , you can do it at |
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| 63:39 | You can sit on a chair or on a desk, cross your legs |
|
| 63:42 | just bang on that uh uh tendon you can get your leg to just |
|
| 63:46 | as much as you want to, ? You shine a light in your |
|
| 63:50 | . What are you gonna get? gonna get a reflex, the pupil |
|
| 63:53 | going to constrict to prevent a light into it, right? So just |
|
| 63:57 | that we are on the same What is the stimulus? It is |
|
| 64:00 | sensory input that initiates the reflex. is the response? Basically the what |
|
| 64:06 | saying is we want it to be . So we're going to exclude as |
|
| 64:10 | neurons as we can. We want as small of a response as we |
|
| 64:15 | . So if it's going to be neurons, great. If it's three |
|
| 64:17 | , that's fine. If you go three neurons, it's going to be |
|
| 64:20 | little bit more complex and it's not to be as fast as it needs |
|
| 64:24 | preprogrammed, you will always, always, always get the same result |
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| 64:27 | if you fight it. So if try to do that knee reflex and |
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| 64:30 | try to sit there and fight You cannot win. It will always |
|
| 64:34 | . All right. Have you ever to fight it? It's like I'm |
|
| 64:38 | gonna let you. All right. lastly, it's involuntary. You cannot |
|
| 64:43 | , it can't be suppressed. There two kinds of reflexes. One is |
|
| 64:48 | , one is conditioned. Basic reflex those reflexes that are unlearned. They |
|
| 64:53 | in responses. You look at a and you smile at it and you |
|
| 64:57 | , what's the baby gonna do? gonna smile right back at you. |
|
| 65:01 | a, that's an innate response, ? Baby doesn't have gas. Baby |
|
| 65:06 | responding to the facial stimulus, the . Oh, there's a face. |
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| 65:11 | respond with the face. That's what do. Ok. Condition reflexes, |
|
| 65:16 | and learning. You all are We're all conditioned, right? We |
|
| 65:23 | a red light or a yellow What do we do? We speed |
|
| 65:26 | ? Right. Well, you've learned Pavlov and his dog, Pavlov rang |
|
| 65:30 | bell fed the dog rang the bell the dog rang. The bell. |
|
| 65:34 | feed the dog. What happened? , the dog bit Pavlov. |
|
| 65:38 | No, he salivated, right? been in classrooms your entire life when |
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| 65:45 | hear that bell go off. What you do? Pack up, get |
|
| 65:48 | and leave. You are conditioned just the dog. All right, we |
|
| 65:52 | are. So this right here is basic spinal reflex. So you can |
|
| 65:58 | this is very similar to the picture just showed you, you can see |
|
| 66:01 | here, I've got my electric I've shoved it into the tissue. |
|
| 66:05 | . It's electric because of the lightning , or is that just pain? |
|
| 66:10 | , it's pain. Ok. I electric better. All right. |
|
| 66:13 | what we have here is we have aspects of a reflex arc. |
|
| 66:16 | very simple. We have a receptor order to detect, um, or |
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| 66:21 | a response. You have to have that actually does the detecting. So |
|
| 66:23 | receptor is the first stage in a . Then that signal that is being |
|
| 66:29 | must be sent up via a sensory . So we refer to this as |
|
| 66:33 | A pathway. So the AFA pathway the signal in, you need to |
|
| 66:39 | that information. That would be the center or the inter neuron in this |
|
| 66:43 | or an integration signal. Then once response has been determined or is determined |
|
| 66:49 | really this is binary stuff. It's fire, don't fire. That's, |
|
| 66:52 | the type of processing we're talking about , that signal is sent outward and |
|
| 66:57 | goes to the E factor. So have an A E pathway to the |
|
| 67:02 | effector. What do infectors do they the effect? Keep it as simple |
|
| 67:06 | possible. So, receptor, a integration center, efferent pathway effector, |
|
| 67:14 | have different types of reflexes. We ipsilateral and nips lateral reflex is when |
|
| 67:18 | on the same side of the If you put your hand on a |
|
| 67:21 | stove, you pull it away, don't pull your other arm away. |
|
| 67:25 | the same side. Right. That be ipsilateral contralateral is on the opposite |
|
| 67:31 | . If someone grabs you and pulls towards them, you push away with |
|
| 67:34 | opposite side of your or the other , that's a contralateral reflex. So |
|
| 67:40 | can have both. You know, , that was one that's called a |
|
| 67:44 | reflex. We'll see this here in a second. So we have monosynaptic |
|
| 67:51 | . What do you think monosynaptic means synapse, polysynaptic, more than |
|
| 67:57 | All right. So that's what this showing you here is a simple stretch |
|
| 68:00 | , stretch reflex. You can see the knee with the hammer, detect |
|
| 68:04 | in uh with the uh the the the muscle spindle. What causes |
|
| 68:10 | goes in? Notice there's no it just goes right back to the |
|
| 68:14 | to cause me to kick out. other words, cause the muscle to |
|
| 68:19 | , right? That's a simple example a mono very, very simple direct |
|
| 68:24 | between the sensory and the motor with . You're gonna have one or more |
|
| 68:29 | neurons in between the fewer the So again, here it is, |
|
| 68:32 | burning, you're in the lab. the guys let you work with Munson |
|
| 68:37 | ? Are you sure? OK. I know like in the high |
|
| 68:40 | they stopped allowing people to work with burners, right? So it's because |
|
| 68:44 | this, right? Here. It's I'm supposed to put my hand on |
|
| 68:47 | Bunson burner. No, burn right? You're feeling the heat processes |
|
| 68:52 | move your hand away. So what you do that goes down to the |
|
| 68:55 | ? So the inner neuron serves as processing unit here. Probably the reason |
|
| 68:58 | you need this processing unit is again you need to uh uh relax the |
|
| 69:03 | , the antagonistic muscle. So this the example, what we just saw |
|
| 69:07 | the stretch reflex. Um We've already about this, so I'm not gonna |
|
| 69:12 | over it again. All right. was what we talked about when we |
|
| 69:15 | about the stretch and the Golgi notice the Golgi tendon, not gonna talk |
|
| 69:19 | it again, but it's again, type of reflex withdrawal, flexion |
|
| 69:25 | All right here, we can see are we doing. We're stepping on |
|
| 69:29 | electric snail shell. All right, I step on a lego, what |
|
| 69:34 | I do? Pull my foot But if I didn't put my foot |
|
| 69:39 | , what would I do follow my ? Right. So, with this |
|
| 69:44 | of reflex, I'm picking my foot . But at the same time, |
|
| 69:47 | have to put the other foot down stabilize myself. So we have withdrawal |
|
| 69:53 | flexion. That would be a contralateral . The other example is if you're |
|
| 69:58 | assaulted, right? And this is I was using before, since you're |
|
| 70:03 | in your handwriting. If I grabbed like so and pulled you towards |
|
| 70:09 | she should, if it was, this was an example of like, |
|
| 70:12 | was like, oh my goodness, grabbing me the way she would fight |
|
| 70:16 | me would be to push with the arm. And that is a withdrawal |
|
| 70:19 | reflex as well. All right. for interrupting your writing. These are |
|
| 70:30 | of innate reflexes. These are not reflexes. No one teaches you how |
|
| 70:35 | do the withdrawal reflex, you just it. All right. One of |
|
| 70:41 | other things this is we're changing shifting . This is not about reflexes. |
|
| 70:46 | are done with the reflexes. One the things that we do is we |
|
| 70:50 | within our brains, these regions that called CPGS or central pattern generators. |
|
| 70:55 | what they do is they allow you create those rhythmic activities in your |
|
| 71:00 | So here's some examples, walking is activity, right? Chewing, looking |
|
| 71:06 | , you went chewing gum. usually when that happened, everyone just |
|
| 71:10 | , you know, trauma from junior , that little old teacher spit in |
|
| 71:14 | head, spit in my head, . So chewing is an example of |
|
| 71:20 | rhythmic activity. Breathing is a rhythmic and this happens because of a combination |
|
| 71:26 | these reflexive activities plus voluntary activities. there is some reflexive in them and |
|
| 71:33 | we have a picture of a cat it's really easy to see this when |
|
| 71:36 | measure and see what's going on. the extensions and the flexor, you |
|
| 71:40 | see how the patterns are opposite each . Right? I mean, here |
|
| 71:43 | got a flexor then extensor, flexor . And if you ever watch a |
|
| 71:47 | walk, you know, because they're cool for everybody. They're just |
|
| 71:52 | right. And it's just doing the each time this is occurring primarily in |
|
| 71:58 | brain stem. Even in the higher , there's some pacemaker activity that's |
|
| 72:04 | There's some other synaptic interconnections do not the next slide down. This is |
|
| 72:12 | example of AC PG. All you can see here, I have |
|
| 72:18 | pattern going in another one going So this is telling this neuron to |
|
| 72:23 | . This one telling that neuron to . But look at all the interneuron |
|
| 72:26 | between. All right, you see going on here is we're basically as |
|
| 72:31 | as this signal comes in what they're . It's saying you tell that one |
|
| 72:34 | fire, but I want you to this one not to fire. So |
|
| 72:37 | one doesn't fire and it waits its and then this one's firing. What |
|
| 72:41 | doing is it's telling that one not fire. So what you're doing is |
|
| 72:44 | alternating this pattern so that you get alternating pattern of reflection and extension. |
|
| 72:50 | right. So this is just an of AC PG neuro mapping is the |
|
| 73:03 | stuff. And I think it's the stuff which is very dangerous when I |
|
| 73:06 | across cool stuff because what does I'm gonna talk a lot. All |
|
| 73:12 | . The gist of neural mapping, is, this is the walkway is |
|
| 73:17 | your brain is not simply a bunch cells, a bunch of wires that |
|
| 73:22 | been jammed into your skull. Kind like we, the way we treat |
|
| 73:26 | when we were working with stuff, a high degree of organization to the |
|
| 73:31 | system. All right. So what going to see in a neural map |
|
| 73:37 | how your brain organizes itself so that it receives information, it knows exactly |
|
| 73:44 | that information is coming from. And exactly that modality is to put it |
|
| 73:49 | another way, the language of the nervous system is action potentials and graded |
|
| 73:55 | . Your brain doesn't know technically whether not a neuron is sending a signal |
|
| 74:01 | light, sending a signal about mechanical about pain or whatever. It's what |
|
| 74:08 | receives in a particular location that tells what's going on. Does that make |
|
| 74:14 | sense? And it's because of these maps, these neural maps that it's |
|
| 74:18 | for itself. So for example, we deal with the somatic sensory |
|
| 74:23 | motor cortex, so the sense of and where it comes from and what |
|
| 74:29 | of the brain are responsible for what of the body. This is the |
|
| 74:33 | . So what we're looking at here a somatotype organization, right? In |
|
| 74:39 | words, we're mapping the body along specific pathway so that it matches where |
|
| 74:46 | comes from. All right purple area there. That's the motor cortex, |
|
| 74:51 | light blue, that's the spa century . This is the precentral and the |
|
| 74:55 | gyrus respectively, right. So always, always, always precentral gyrus |
|
| 75:01 | gonna be the motor cortex. Postcentral is always always, always a spa |
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| 75:05 | cortex information. I'm just gonna come here if I want to make my |
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| 75:13 | wiggle, this is the part of brain that sends signals to make my |
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| 75:17 | wiggle. If I am getting poked the butt, I go up there |
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| 75:23 | you can see exactly where that information going to be sent, right? |
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| 75:28 | have an arm and look how big arm is. Look how big my |
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| 75:31 | is. Why is my hand so on this map? That's the sensor |
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| 75:35 | at the top sense of touch. have lots and lots of tiny, |
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| 75:41 | receptive fields and they overlap each And so this gives us our fine |
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| 75:47 | of what's going on. Notice that area that makes up my say my |
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| 75:52 | thigh, not a lot of receptive because it doesn't matter what's touching me |
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| 75:56 | my thigh. As long as I something's touching my thigh, right? |
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| 76:00 | I need to know what's going on my hands because the world revolves around |
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| 76:05 | hands. Be touching things. What my lips? Look at my lips |
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| 76:09 | there? Why are my lips so ? Why do you think the sense |
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| 76:13 | touch around my lips is so A good answer. I was waiting |
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| 76:22 | someone said because kissing feels good. no one again, you all need |
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| 76:28 | get out more. All right, big because of we need to detect |
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| 76:34 | we're putting in our mouths. Have noticed that coffee burns if it burns |
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| 76:39 | mouth, what do you think it to your insides? It burns it |
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| 76:43 | , really bad because this is far protective than what's going on inside, |
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| 76:49 | ? You know, if you feel sharp, hard pointy, you |
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| 76:53 | you need to know here before it and causes damage elsewhere. All |
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| 76:59 | Again, the face, things touching face or making my, well, |
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| 77:03 | touching my face down here. That's . So why motor is so big |
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| 77:07 | the face? What's the, what's primary form of communication? Humans use |
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| 77:13 | expressions, right? So this just you again, look at the organizations |
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| 77:19 | , very specific. These are called Somatic century homunculus. And the motor |
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| 77:24 | mucus means human. Like notice it's exactly like a human, it's very |
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| 77:28 | close to a human. If you that thing walking down the street at |
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| 77:32 | , you'd probably freak out as would else retinoic map. What we have |
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| 77:39 | is a map that matches the All right. So remember how we |
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| 77:43 | a retina, we spread it out this. And if it's nice and |
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| 77:46 | , what we're saying is when light this portion of the retina, there's |
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| 77:49 | specific part of the brain that receives signal that says light hit this portion |
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| 77:52 | the brain. And so your brain where the light is hitting on the |
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| 77:57 | . And what it's doing is it's all those light signals and putting them |
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| 78:00 | and then processing it to help us the world around us. All |
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| 78:06 | So you can see how they cross . This is what gives us our |
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| 78:10 | vision. But all we're doing here we're just saying where does the light |
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| 78:15 | if we're talking about other aspects like movement? There's other maps. And |
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| 78:20 | I think I mentioned to you No, I didn't. Actually, |
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| 78:23 | I mentioned to the A MP group when it comes to the brain and |
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| 78:29 | the visual understanding, most of our processes. For the for vision, |
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| 78:36 | have color maps, we have movement , we have all sorts of crazy |
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| 78:40 | everywhere. And it's what happens is take an image of things we're looking |
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| 78:45 | and we break it down into its parts and then we put it all |
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| 78:48 | together and that's what our perception is on these different types of maps. |
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| 78:53 | the retina topic is again, it's somatic map. It maps to the |
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| 78:57 | of the retina itself and where light hitting the retina. The last |
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| 79:03 | Yeah. Is the map for hearing way that hearing works? Is that |
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| 79:08 | you've ever looked at someone's ear, noticed that? It's kind of weird |
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| 79:11 | . It looks kind of like a peach. Right. It's kind of |
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| 79:14 | . The more you look at the weirder it looks, but it |
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| 79:17 | has a shape for reason because it sound waves to hit it and bounce |
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| 79:22 | very specific ways. So that sound down through the auditory canal or auditory |
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| 79:26 | to that Tian membrane and it carries it directional information. So when it |
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| 79:33 | to the vertical plane, how sound those different things is basically where is |
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| 79:39 | reflecting? So if the sound is from high, it reflects differently |
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| 79:42 | when sound comes from below. And it creates a unique pattern in as |
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| 79:48 | goes down the ear to tell oh, here's, it's verticality, |
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| 79:52 | kind of cool. All right, it comes to horizontal sound, depending |
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| 79:57 | if it's a high note or a note, you're creating the sound |
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| 80:02 | All right. So sound shadows look you can see up top, there's |
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| 80:05 | high frequency sound. So you can the waves are really, really |
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| 80:08 | And so when they hit the body the opposite side of you, those |
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| 80:11 | waves are not able to come around the ear, they basically create a |
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| 80:15 | . So you hear it on this , but you don't hear it on |
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| 80:17 | side. And so it's picking up sound on one side and not on |
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| 80:21 | other gives you a sense of But when it comes to large |
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| 80:27 | you don't get that shadow. it's just, it hits this side |
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| 80:30 | then a couple of milliseconds later it that side. And so hearing it |
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| 80:34 | both ears tells you again, So it works a little bit |
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| 80:40 | And again, this is a little complex. I show this to you |
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| 80:44 | I think it's interesting. This is last slide and then we're done, |
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| 80:47 | ? So that sound when it comes , it's going to go to both |
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| 80:52 | , right? And so you're picking up from both sides and that information |
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| 80:56 | sent to the medial geniculate nucleus. here what we have is we have |
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| 81:02 | that is travel or the actions that traveling to these regions in the uh |
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| 81:10 | O is the the super optic Is that right? Yeah, superior |
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| 81:14 | region, sorry. And what we is we, in essence, we're |
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| 81:19 | to match the sound on both And so if, if the action |
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| 81:24 | from this direction meets up with an potential at say at this point that |
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| 81:28 | tells you something or if it's here if it's here, it's here. |
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| 81:31 | what you're doing is if they don't up your brain kind of says, |
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| 81:36 | I'm going to go ahead and say this is coming from this side or |
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| 81:41 | side, it's how we perceive that timing and the frequency in this |
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| 81:47 | that helps us understand how sound is arriving. And then it goes up |
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| 81:52 | the brain and then the pitches and are going to be mapped, kind |
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| 81:56 | like the keyboards of a of a of a piano. So high notes |
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| 82:00 | gonna be located in one region of temporal lobe, low notes are in |
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| 82:04 | other ones. And so you're basically along that thing just like we saw |
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| 82:08 | the homunculus. So if I'm stimulating part of the temporal lobe, high |
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| 82:12 | over here, low note. So this processing helps us understand the world |
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| 82:17 | us because we've prema everything and use really, really cool stuff. This |
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| 82:24 | what's called a delay line and it's like I said, if you're, |
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| 82:27 | you're a biomedical engineer and an you kind of look at this and |
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| 82:29 | , this is really cool because it's making circuits talk to each other and |
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| 82:33 | they fire at the same time then we know where the sound is |
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| 82:36 | from. That's the delay. I kept you guys an extra two |
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| 82:43 | . I want you guys to have great weekend. What are you supposed |
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| 82:46 | do? Go out and get out |
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