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BIOL 2301 Human Anatomy & Physiology I - 2301_lecture20_1111
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00:00 All right. So we already talked that. People listening at least I
00:08 this out in the first three minutes of The last three minutes of
00:12 Right. All right. The second has to do with recruitment and what
00:18 is really saying here is that when looking at intensity and strength of
00:23 it's not just going to be one that's going to be stimulated. What
00:28 is is that as a receptor stimulated is a range at which you can
00:32 stimulated. There is a low there is a high point. You
00:34 imagine Number one kind of represents that of that one receptor but there's receptors
00:40 it that will also become stimulated. greater the intensity. Alright, so
00:46 easy thing you can think about if want to want to think about
00:48 let me dig in here and find sharp. I'm going to stab somebody
00:52 this often I guess I'll stab All right, So, if I
00:55 this pin, you have a really tiny point. Right? If
00:58 touch myself barely, you can look that, you can do this to
01:02 . You can see that the skin of intense. Right? The harder
01:05 push in. Right, I'm going start not only affecting where that pin
01:10 pushing, but I'm now affecting the neurons the nearby receptors. And so
01:15 getting stimulated. And so now the is not just being recorded by the
01:20 receptor, but it's being recorded by receptors that surrounded and so they have
01:24 series of overlap. Right? And there's different thresholds obviously as this one
01:32 right here. So as this one to climb, you can see this
01:35 starting to turn on when it's around . We're at a low intensity
01:39 So, you can imagine now the is being bombarded not by one receptor
01:43 by two receptors. And then now we get up to here, we're
01:47 starting to reach the max. This is really turned on. This one
01:51 kind of turned on. This one starting to turn on. And so
01:54 what's the brain is doing is it's receiving information from more and more
01:59 So, intensity is not only recorded the number of action potentials, but
02:04 the recruitment of other signals from other . That kind of makes sense.
02:10 right. That's what all this Right. So, intensity number of
02:14 recruited. Now one of the things your brain likes to do before information
02:21 gets to it or what your body to before information gets up to your
02:24 is to modify the information so that is greater clarity and greater understanding of
02:30 happening. All right. So, what we're saying is that information is
02:34 modified even before it gets to the kind of neat. Right,
02:39 how does this happen? Well, we're trying to do is we want
02:44 identify in this particular case exactly where stimulation is taking place. And so
02:50 can see here again, using the of a pen, you can see
02:54 pen is poking right here in the so the b neuron is being stimulated
02:59 you can also see that the And the C. Neuron are slightly
03:02 stimulated. You can imagine the harder pushed down, the more it's going
03:06 do, the more things that are to be stimulated right as I'm moving
03:09 further and further out. Now if want to pinpoint where this particular stimulus
03:16 coming from, what I want to is I want to highlight that place
03:21 I want to diminish or lower the that are only subtly being stimulated.
03:28 that make sense? Right. So other words, if there's not three
03:33 you sitting next to each other really , but let's say there's something here
03:37 stimulating right here, I want to over on this side. So this
03:41 really stands out, right? And what lateral inhibition does. It
03:46 look, I'm being stimulated more than other two. So when this neuron
03:49 stimulated, it actually does lateral inhibition basically block the signal coming from the
03:56 receptors. And so what the brain not seeing is something like this
04:00 it's seeing something like this. So goes ah ha that's where the stimulation
04:05 taking place and that's the purpose of inhibition is to create greater contrast in
04:14 area of stimulation so that you can specific locality of stimulation. Okay,
04:24 this isn't just happening in the this happens all over this happens in
04:29 gustatory system, happens in the auditory . It happens in the nasal
04:35 the olfactory and the visual systems as . All right. One of the
04:42 our eyes do remember, I'm going get to the eyes a little bit
04:44 today, someone kind of focus little . One of things our eyes do
04:47 does lateral ambitions. So that shadows darker and lights look lighter and that's
04:53 before that signal leaves the i it lateral inhibition to ensure that happens.
04:59 we're gonna talk a little bit about system in just a bit and again
05:03 I when I say talk about like our toe in and then kind of
05:06 away very quickly. All right. in order for information to get up
05:14 the brain, it has to follow pathway. And this is the somatosensory
05:18 . All right. And so this that place where I told you on
05:21 ? It's like I'm trying not to you guys, but I'm just letting
05:23 know when you see big words don't . Right? What do we
05:27 We look at them and ask the , what is it telling us?
05:29 so these are taking those peripheral In other words, we're receiving information
05:36 external sources and we're moving it up the brain. So we refer to
05:41 ascending pathways. Right? These are you're below the neck, what we're
05:47 to be using is we have to the spinal cord to get there.
05:50 right. So you're gonna always c . Oh, in the name
05:54 Alright, if they're above the Well, the nerves that are located
05:58 , those are the cranial nerves. so here we don't have the
06:03 you know, the spinal in the name. All right. So these
06:07 going to carry that a different signal into the brain itself. All
06:12 So we're primarily gonna be looking right at these below the neck. So
06:16 two major pathways are called the dorsal pathway and the Antrel Latell pathway.
06:22 we're going to see that they have other names that kind of help clarify
06:27 . When you're looking at the dorsal . So, I want you to
06:30 about when we talked about the spinal . Remember we said we had White
06:35 , right? The White Matter represents moving up and down. And we
06:39 there's three different regions right? There the dorsal or posterior particularly. We
06:47 they were the lateral for Nikolai. then we said there's the anterior or
06:51 fin Nikolai. So when you hear words dorsal, anterior and ventral or
06:57 anterior lateral um or even posterior. you hear any of those terms in
07:03 , those are the areas they're referring . It's either the ones on the
07:07 , ones on the front side or there on the sides. All
07:11 So, when you're seeing dorsal it's going to deal primarily with fine
07:17 , inappropriate exception, appropriate reception Is your head or your body's understanding
07:23 where your body parts are in terms space and locale. All right.
07:30 Antero lateral pathways primarily deal with pain temperature. So you can already see
07:37 going up to the brain and the receptors are already separated so that your
07:44 knows what type of signal it's All right. Put it another
07:52 Um The difference being tickled by a and getting hit by a hammer,
07:59 pickle. It would be fine Right, hammer down there in
08:07 So, it's a different pathway. right. The sensory pathways have always
08:17 , always three neurons having neurons. neurons. They have simple names.
08:23 started neuron, That's the first the second order neuron, That 2nd
08:29 and then the 3rd order in All right. So, what we're
08:34 to is the direction in which the is going since it's coming from the
08:38 going up to the brain. First neuron is going to take information from
08:41 receptor and may include the receptor. might be the receptor and it's going
08:46 take that information into the spinal All right. The cell body of
08:53 . Remember, Always, Always. . Always Because this is a sensory
08:58 resides in the dorsal root ganglion. right now, I think your book
09:04 to as a posterior. So, used to teaching at dorsal dorsal and
09:09 interchangeable words. All right. Do remember where that ganglion is? Do
09:13 need to draw the picture on the you remember? All right. You
09:18 you remember? You remember? it's that big lumpy thing on the
09:23 , Right? It's only on the root. You don't have a lumpy
09:25 on the on the on the ventral . All right now, what they're
09:30 to do is they're projecting to the neuron. That's easy. Right?
09:35 order goes to secondary order or the order neuron. All right now,
09:41 is going to be residing either in posterior horn. So, right
09:45 we're showing it down here. We're pretending that we're looking at the at
09:49 spinal cord. So, there's the body. There's a posterior horn or
09:53 neuron that first order on can travel the way up and then it goes
09:58 the brain stem. So, the place it could be located to be
10:01 the brain stem. But so, one of two places. So,
10:04 can see the first order of neuron have different lengths. You can just
10:07 in immediately uh synapse or it can travel all the way up and then
10:12 apps. And that's where the second neuron is. Now at some point
10:18 going to devastate. All right. either the second order neuron is going
10:22 decorate from the brain stem there or going to devastate down here at the
10:26 cord very rarely does it go straight and deca state up higher? So
10:31 usually devastating just after where you have synapse. Alright, and then what
10:37 is doing is it's traveling up to thalamus and the purpose of the thalamus
10:41 we said is to sort information, where that information is to go.
10:45 so the cell body of the third neuron is always gonna be in the
10:48 because that's where we're going, right then what it's gonna do, It's
10:52 to project the somatosensory cortex on the lobe. All right. So this
10:57 a touch. This is about touching being touched, knowing what you're
11:01 And so this gives you that conscious of Oh, I'm touching X.
11:07 . So first order neuron takes it either terminates in the spinal cord right
11:14 right or travels up to the brain where you're going to see the second
11:18 neuron. The second order neuron is to then cross or deca state and
11:23 travel up to the thalamus and then third order neuron is located in the
11:26 and goes to the somatosensory cortex. right, So that is it.
11:34 it's organization. So let's look at . All right. The dorsal
11:43 Now, this is the pictures are little bit clear here. So that
11:46 can kind of see where we're All right. The dorsal column is
11:50 called the dorsal column, medial meniscal . Wow. A bunch of words
11:56 there. All right. Do you learning about the medial meniscus when I
12:01 it out a long time ago, the brain stem? It was like
12:05 two weeks ago. Yeah, It's like forever. Right. But
12:12 reason I pointed out is because here is. All right. Now,
12:17 what we said. Doors, columns fine touch inappropriate reception. If we
12:21 to identify the fibers, they they're beta. So, they're like the
12:25 sized fibers. Alright. So, we look at the primary neurons,
12:29 primary neuron enters in and goes to dorsal root ganglia. Right? That's
12:36 , that's where the cell body goes . And then it's going to find
12:39 of two pathways. If you're in lower part of the body.
12:43 down here, you're going to find pathway that's called the physical is gross
12:48 . Ooh, that's a tough All right, folks. Isc vesicular
12:53 . All right. You guys what fashion is. Alright. Fashion is
12:58 that wraps something right? You're used probably the term There we died.
13:03 right. Good news. I got of batteries. Yeah. You
13:09 I talk a lot of the batteries . Everyone's fine. Yeah. Just
13:18 that orange light. Mhm. Imagine going to sound fun on the recording
13:41 . Just popping and popping. Shake . Shake. I got the star
13:49 version of that one. A Little two D 2. Alright. There
13:53 go. Okay. So, what was gonna show here, we have
13:57 physical us. So, when you physical is it just means tiny
14:02 All right. And really what it ? It's in the dorsal it's in
14:04 dorsal column. And basically what it , a series of neurons that are
14:08 together and and wrapped in connective All right. And what it's doing
14:14 it's going to travel to a nucleus the same name. What do we
14:17 a nucleus in the in the central system, basically what's there? What's
14:23 the nucleus bunch of cell bodies. we learn the nucleus priscilla's and nucleus
14:28 artists at least, Did we identify and point them out in the
14:31 And you remember that? I remember this because we're going to come
14:34 to it. And so you're looking me going, I remember this because
14:37 didn't ask a question about guys and going to come back to it.
14:40 right. And what we're doing is , we're saying here if the lower
14:44 of the body, you're going to from the grocery list and then what
14:47 going is to the nucleus priscilla's and you're in the upper part of the
14:51 , you're gonna go through the uh uh kenyatta's and you're going to the
14:55 kenyatta's So notice where the termination First order neuron goes up to the
14:59 stem. It doesnt deca state, stays on the same side of the
15:03 and goes up there and then once goes into the nucleus priscilla's or the
15:07 kenyatta's, depending on which pathway you're , then you cross over and then
15:12 move up to the thalamus and from thalamus. Use the third order on
15:15 get up to the somatosensory cortex. right. And what are we
15:22 Find touch. So real simple dorsal . Find touch inappropriate reception. We're
15:29 one of two pathways to picking up where we are in the body.
15:33 right, you don't have to pronounce the exam. Do you try to
15:36 particularly sorry for this? Plastic, vesicular. It's ridiculous that you have
15:44 say vesicular this. Oh, all , great sillas and kenyatta's right and
15:51 just going to the nucleus chrysalis in nucleus Kenyans. Now, what I
15:54 to point out here is I'm just highlight this just because I've said it
15:59 and I want you to understand the is incredibly organized. So it exhibits
16:03 is called soma utopian summon utopia simply just the conserved organization that reflects your
16:10 organization. So the uh sensory neurons are four years small art for your
16:17 are gonna be more centrally located say, the sensory neurons at your
16:21 , which is more centrally located than one from your hip and so
16:24 and so on, and so You're just kind of pushing things
16:28 Right? And if you can't visualize , I want you to think about
16:31 highway, Right? If anyone here the 59 uh exchange right there to
16:38 , how many lanes? I'm pointing how many lanes there's two,
16:41 And then another line comes in And three, and then from three goes
16:44 4, 4-6. And then it right back down to four again,
16:49 ? But it's not like that fourth like joins like in the middle,
16:53 ? It's always just adding on one and that's kind of what you're doing
16:57 . You're always adding in on the and pushing things in with question.
17:09 . Mhm. So, the question , is the dorsal pathway from,
17:17 it in the spinal cord from? , I could use All right.
17:24 want to see if I I do a picture. Okay, So,
17:26 gonna don't read the slide yet. just gonna use this as a
17:30 All right. I'm gonna show you the dorsal column is, right,
17:33 column. Is this stuff right back . This would be the lateral
17:40 This would be the anterior column, ? So it just shows you
17:44 right? And so what, what? This show pictures showing you
17:49 showing you is saying these to come and what they're doing is they're traveling
17:55 in this structure right here. So they're coming in from this side,
17:59 they're doing is they're joining up in physical US groceries and the kenyatta's are
18:05 up the length of the column in region And that's kind of the nice
18:10 about this is the first time you at this, you want to throw
18:13 hands up and say this is scary complex and trust me, if you
18:16 you take a neuro anatomy class, don't just learn the two, you're
18:20 to learn like 50 of them. not trying to scare you away from
18:24 school. I don't think you have do that in our school. But
18:25 school, I know they do that they have to know everything and then
18:29 forget it all. Mhm. ask him next time I go to
18:33 doctor said, can you tell me different names of the different pathways that
18:36 found in the dorsal column and just your eyes. But for a second
18:39 then they're going to him and You know, we don't really need
18:42 know that anymore. I promise My doctor hates me, come in
18:51 always ask questions and he just kind like crap. I think he has
18:54 review before. I can show All right. Anyway, so that
18:58 the idea. So, when we're about these tracks, they're like remember
19:02 are mirrored. So you can just it's over on. If I'm coming
19:05 this side, I'm traveling up that side to get up to the nucleus
19:09 or the nucleus kenyatta's. Okay, makes sense. Cool. All
19:13 So, I don't think I need cover anything else on this.
19:18 Just oh, they're using the medial pathway to get to the thalamus.
19:22 the media la la meniscus is what doing. And again, if you
19:25 back and look at those pictures I you, I think they showed you
19:28 one slice and it said like this the medial meniscus but basically it's a
19:34 that travels up to the thalamus. right. So the mantra lateral system
19:41 basically saying we're going to use both lateral and the anterior for Nikolai to
19:46 information up, we have a different for it. Sometimes you'll see spinal
19:50 pathway that makes your life easy, you the spinal cord and it's going
19:54 the thalamus. All right. We said it's going to be pain and
19:57 , it's going to be uh a fibers. And some of my uh
20:02 elevated C fibers. Alright, three path or three chains. So
20:07 the primary, the secondary and the remember secondary is gonna be the
20:12 You can see what we do The primary comes in, right?
20:16 a cell body there in the dorsal ganglion and it's going to synapse in
20:21 gray matter. So in the dorsal and then it's going to then cross
20:28 , right? And it's either going travel the lateral or the Antrel
20:32 So which one is it going to ? Well? If you're in the
20:34 body, you're going to travel via lateral pathway. If you are in
20:39 upper body, you're going to travel the anterior pathway. All right.
20:44 that's the distinction there. It's just where where you're coming in as part
20:49 the body. And what it's gonna is going to completely project all the
20:52 up to the foulness. So, can see I'm getting my devastation at
20:55 level of entry. Right? I come in as a first order
21:00 . I cross over as a second neuron and then I can travel all
21:03 way up to the thalamus via that . All right. And then
21:10 projecting to the portion of this Mattis cortex I need to go to.
21:15 , pain and temperature. Now I don't know why through these slides
21:25 here. Maybe this is just the I've always taught it and then it
21:28 make sense to me. And that's I put them in the wrong order
21:30 you guys. Um or the right . I don't know but really what
21:34 want to point out here is that receptor in your body is uh is
21:41 as a specific form of energy. right. So, what we say
21:44 that it has a specificity towards a type of stimuli. All right.
21:49 so what we're doing is we're transducers signal. We talked about that transaction
21:53 week, basically my I cannot All right. The receptors in my
21:59 are incapable of binding to chemicals and to them. All right. I
22:06 take light and shine them into my as much as I want to.
22:10 I will never smell light. I can't do that wrong types of
22:17 . All right. So, when talk about this conversion, what we
22:21 doing that we're really talking about activating receptor. And so when you hear
22:24 word receptor potential, it's usually graded . And what it's doing is
22:29 we're activating the receptor. And then there that we're gonna get the action
22:34 that causes some sort of activity And so that would be the transaction
22:39 is activating the receptor. So, this particular case, we're looking at
22:44 receptor releasing a neuro transmitter. So activating via chemical to get the neuron
22:51 then see the signal up to the . So now we're talking the signal
22:54 the type of the the type of that the brain best understands. And
23:01 think I keep going back over this because it becomes really important to remember
23:06 we're always talking to the brain with or electrical signals. Now, I've
23:12 talked about adaptation, so I don't we need to go over this again
23:16 the third time. But that's where slide used to reside. So everything
23:22 going to do now from now until until like the second last lecture is
23:28 going to be general or special And today, what we're gonna
23:31 we're gonna talk about the eye and not going to dive completely into
23:35 We're gonna do most most of the today. And then we do a
23:38 bit more on Tuesday. And so so that you understand, we're really
23:42 be looking at three different types of here. And we're ultimately going to
23:47 most of our time down here eventually this is where all the cool stuff
23:51 going on. But in order to what the cool stuff is, we
23:54 to know the other stuff that's going around it. So the eye is
23:57 spherical. It's not entirely spherical. it's not perfectly round. It's found
24:01 your orbit, which you've already um and it's cushioned on all the
24:05 by orbital fat. So if you and pull your eye out, you'd
24:08 there's a bunch of fat in there that's just there to protect it.
24:12 don't want to pull your eye Okay, please don't do that.
24:15 right now the three layers. All . You can see here is the
24:19 tunic the vascular tunic and the nervous . So you can see we're gonna
24:23 working away from the outside inward. out here there's your fibers tunic,
24:27 red stuff, that's your vascular tunic then the little yellowish brown stuff.
24:32 your retina or the nervous tunic. . And so within these on the
24:38 the fiber student we have this Clara the cornea. All right. The
24:42 tune It includes your iris and includes that you're probably not familiar with.
24:47 is the silly everybody in the Oid which provides the nutrients for
24:51 And then the retina is the layers has the the retina is basically the
24:57 actually detects light and then there's pigment there to prevent light from bouncing
25:02 It absorbs up light so that light works in. I mean only stimulates
25:07 eyes or your receptors once. All . And so what I wanna do
25:11 I want to first focus on what is um it is a wave and
25:17 a particle. It's one of those things that's nice and confusing. And
25:21 really cool is if you go onto , this is actually a movable gift
25:25 if you watch that you'll become mesmerized a little while because it sits there
25:29 does this weird thing because it's not wave like a rope or you can
25:32 a rope and get that wave to of go through. It actually has
25:36 axes. And so these two axes working opposite each other ones a magnetic
25:43 . One is the electrical field. it's like I said, it's it's
25:48 just gonna say it's beyond my That's physics stuff. All right.
25:51 . I know your house is like . All right. But what you
25:58 understand is that this is part of electromagnetic spectrum. So, here's the
26:03 electromagnetic spectrum. Right? And so can detect electromagnetic radiation. It's just
26:12 call it visual light or visible All right. That's just the
26:16 But you can see in here there's there's infrared microwaves, radio waves.
26:21 are all different types of electromagnetic There are some species that detect UV
26:27 . You guys know what species does birds. Which clothes rats?
26:33 no, no, not rats. bats, bats use sonar. That's
26:40 . No, that's infrared. All . It's beads bees. They see
26:48 the U. V. Spectrum. in fact when you go look at
26:51 flower, how pretty what you really to see is what that flower looks
26:56 under UV light because it looks like big giant arrows pointing to where the
27:01 yummy nectar is and where all the is. So that he goes I'm
27:05 there and then it gets all that on its butt and it kind of
27:08 around in it and it carries a to the next flower to get its
27:11 little nectar. And what it's doing that's the birds and the bees conversation
27:16 you guys get to have. But that's UV light and it looks
27:20 arrows. You can actually when you at it like they're literally things just
27:23 of pointing saying this is where you . So the the flowers use UV
27:27 you ve uh Well they take advantage that spectrum so that bees can see
27:33 they need to go. All The other one infrared um You said
27:37 . So pit vipers um uh Some the constrictors, they have these pits
27:43 their faces. Pit viper, it's says their name has a pit.
27:48 within those those are infrared receptors that electromagnetic radiation in that range. So
27:54 how they detect heat. That's when know when to strike. Really kind
27:58 cool. All right now, all radiation are composed of photons which makes
28:05 Really, really interesting. When you to physicists talk about photons in one
28:09 to talk to a chemist will talk photons. Another way you talk to
28:11 talk about photons another way easy way think about photons as they're packets of
28:16 . All right. And if you take another class like that talks about
28:20 , you'll understand why it's so it's to think about in terms of
28:22 Their packets of energy. and these of energy? These photons are capable
28:28 stimulating the specific types of receptors are in the eyes. All right.
28:33 it's a very very tiny spectrum. again, you don't need to know
28:37 refers to the length of the And so what that means is that
28:41 a wave. We said it's a . And so that means the wavelength
28:44 how long that wavelength is or that is. And we also have
28:49 And so the wavelength distinguishes the amount energy that's being carried versus the amplitude
28:55 tells you the intensity. Alright, intensity is how bright it is.
29:00 right. That doesn't mean just because brighter. Doesn't mean it's more intense
29:03 intensity or sorry, the the energy reflected here in its color. All
29:09 . And you can see down here This would be low intensity. This
29:15 high intensity over here. Is I that Yeah, that's That's right.
29:21 . All right. So, that's we're detecting. All right. We're
29:26 at electromagnetic radiation and so we have specific receptors that are unique to this
29:33 now. We need to protect Right? Because they're very important.
29:37 are very visual creatures. How do know this? All right. Look
29:41 where your eyes are on your Their front facing. We're predators.
29:48 you know that when you walked into bell to get those tacos. Did
29:53 realize you were stalking them? All right. We're not olfactory
30:00 Right? I mean, we can some things but we're not like our
30:05 . Right? It's like I smell . Where is it coming from?
30:09 you start looking for it? All . So our whole existence is dependent
30:15 our ability to see things. And not making fun of here and not
30:18 , you know, saying, oh if you're blind, that's not what
30:21 trying to get at. Right? just showing you why the eyes are
30:23 important. We got to protect And so we have protective structures.
30:26 have eyebrows. Alright, Your eyebrows here on the super orbital ridge.
30:30 ridge actually sits outward so that the are kind of pressed back inward and
30:36 from the external environment. Eyebrows sit and protect the eyes by preventing sweat
30:42 dripping down into them and preventing you scene. In fact, look at
30:48 shape of the super optic in your . Sweat hits us and it drives
30:52 outward and away from the eyes. right. You have to wonder why
30:55 have eyebrows, right? It helps terms of expression like what?
31:01 I'm mad, but it's really there protect the eyes from stuff getting in
31:07 . We have eyelashes. Yeah, pretty right, Guys dig them.
31:13 did. We do all right. really what they do is they prevent
31:18 foreign objects from contacting the interior Try to touch your eyelid or your
31:24 eyelash. What happens? It's like goes no no no no you're coming
31:28 close to the eye and it causes to close your eyelids right. It
31:33 serves as a big giant fan and actually sweeps dust and other particles away
31:37 the eye. All right then we the eyelids that have us name called
31:43 break. All right. The eyelids a superior one. There's an inferior
31:49 and we're really giving this more detail actually needs right. Um has this
31:54 core. There's muscles in them. glands. Um There's the conjunctivitis which
32:00 a protective structure which we'll get to in a second. Well that's actually
32:04 their skin. So that's a structure allows you to shield your eye.
32:09 as that figure comes poking in and , what do you do? You
32:13 it now you have something protecting and touching the front of your eyes.
32:19 now there's some glands in there is have the Tarso glands or the mel
32:22 in glands. These are not easy see if you get in really close
32:26 a mirror. You can look and can see them on the edges of
32:29 pal parade. All right. Sometimes get infected. You get kind of
32:33 bump there, right? They get . Right? And so that's that's
32:39 . It happens with little babies. even worse. What do you need
32:42 get a warm cloth and keep putting on there and hopefully it will open
32:45 . But basically that produces this Bum and the CPM then line the
32:50 of the palpa beret and that keeps tears from just rolling down your
32:54 I'm not talking your tears when you're , I'm talking the tears. You're
32:57 this very moment to keep your eyes . So it basically creates this waxy
33:02 that says liquid stays on the surface the eyes and it's gonna be needed
33:06 be drained in a specific direction. space here is called the palpable
33:13 And then we also have this is favorite word. That's why I put
33:15 up here. The Lakmal cry It's a car uncle? Car
33:21 Is that a fun word? There's fun one in the itunes called the
33:25 of slim. Yeah, yeah. gonna get to the canal show in
33:29 minute. But basically the lack of that little tiny space right here next
33:34 the NATO to the nose and that's little tiny little dip right there right
33:40 are some glands in there that produce gritty particulate that when you wake up
33:44 the morning you call sleep or eye or whatever it is that you grew
33:49 calling him. All right. The . Alright. You've heard of
33:56 Alright. That's an infection of the ? Conjunctivitis is basically a a barrier
34:04 the external environment and the area around eye. In other words, it
34:10 uh serves as that barrier to prevent from getting into your body. And
34:15 really if you if you look carefully on the back of the palpa
34:19 it's that little tiny line that goes and then it comes right over here
34:23 stop. So it covers this clara the back of the um the palpa
34:28 . Alright. It folds on And so we have to have to
34:31 is called palpable, one is called ocular junk of a right and there
34:37 blood vessels in there. And so you get an infection or you irritated
34:41 turns bright pink. Right? And looking at someone's eye, that's what
34:45 looking at. It's like oh there's evacuation alright goblet cells, purpose
34:50 goblet cells to moisten it highly highly vascular rise. And what you're
34:56 is you're supplying nutrients to this clara it's not tight. It's kind of
35:02 and that allows your eye to shift right so you can move your eye
35:06 if it was tight. Your I be prevented from moving so it's loose
35:10 that your eyes can move but it creates a barrier between the external environment
35:16 the inside of your body. The place you're not going to find the
35:20 on the cornea and the cornea is light is going to penetrate into the
35:26 . All right. The lack Rimmel . That's your tear gland.
35:35 produce lactic fluids. It's located out . All right. It's not
35:40 Sorry. She took off my It's not here. It's out over
35:44 . And what you're doing is you're tears here. They wash down over
35:47 eyes and they move inward towards the that are located in that car.
35:54 . All right now, what is tear? There's lots of fun stuff
35:58 this. It is there to lubricate interior surfaces. I basically anything that
36:03 on the eye is going to land that fluid and it's going to get
36:06 away and moved towards those uh those . There's also anti bacterial agents in
36:14 anywhere. There's water bacteria like to . And so there's antibodies and other
36:19 agents that are found in those tears prevent infection from occurring. Um There's
36:26 there's a one of these is called design. And so license I'm is
36:31 in your slide and stuff. The where you find the greatest concentration of
36:34 since I was in the and their . So it's just a very very
36:40 environment. Now you're always producing You're just not producing a lot of
36:45 . You're just trying to keep the over there when you blink your pushing
36:49 fluid towards the medial side of your . And what you're gonna do is
36:55 is the little tiny ducks again. can go to the mirror and you
36:58 go and look and you're gonna, yeah, they're right there. I
37:00 see them. And there are little ducks is paired one on the top
37:03 the bottom there called the punk to what happens if you push those tears
37:07 go into the punk to traveling a tiny canals called Nikolai right canals,
37:13 canal and then it goes into the ball sack, which then empties into
37:16 lateral duct which then goes into your cavity. Now, if you want
37:19 remember the pathway, think about you a blubbering idiot or one of your
37:23 being a bloody blubbering idiot. What there crying and crying and they start
37:27 this horrible noise, right? Because you cry you produce more tears,
37:33 tears and that the wax can hold so they actually pour down your
37:37 But you're still producing tears that are into punk into the curricula into the
37:41 and then down the nasal cavity. that's why you're doing the whole snotty
37:45 stuff. It's basically dripping water in nose and that's why you do the
37:51 . Mhm. All right. The muscles. Now, I'm not gonna
38:00 you memorize these. I don't ask which is which one does which at
38:03 point you're gonna have to memorize I promise you, I guarantee you
38:06 a wicked evil anatomy list in your . Who's gonna say memorize all the
38:12 . All right. These move your around. That's all point of the
38:19 eye muscles. They move your eyes . You can see we have uh
38:23 that move immediately immediately. We have laterally. We have move up.
38:27 have moved down. All right. then we have that can cause oblique
38:31 . All right. So, just can move our eyes because there are
38:36 attach to the outside of the Those are the extrinsic muscles. They
38:40 attached to the fibers tunic to this , the whites of your eye.
38:45 right. So, if you look that fibers tunic, there's two parts
38:52 it. All right. We have clara. That's the white of the
38:55 in the cornea. That's the bump the front of the eye. The
38:59 thing, that's transparent. That allows like to enter into the eye.
39:05 , So, the purpose of these the square is primarily connective tissue,
39:12 what it does is it provides I it protects the eye and allows for
39:17 to be attached to. So, , it's where the muscles can attach
39:21 . Now, if you were to it, you'd see that actually is
39:24 with the dura. So, if follow the optic nerve, there's dura
39:29 on the outside of that. And it just kind of forms the outside
39:33 then ultimately forms a square the cornea what we're actually interested in. There
39:38 actual living epithelium. There's no dead here. This is a very living
39:43 . But you don't want vasculature there that would get in the way of
39:47 coming into your eye and interfere with seeing things. So there's no
39:52 You have to get your nutrients from surrounding environments from the fluids that are
39:57 on either side. Now, what does, It basically allows light to
40:02 into the area into the interior the where the neurons are and the cells
40:07 the receptors are located. So those located in that inner layer. The
40:12 thing that does, it bends light . This is the whole physics
40:17 Um And no medical school and dental require Physics. I don't know about
40:22 school. Does it require Physics? , optometry school is going to require
40:27 at some point. Physics two deals two subjects. Everyone hates physics
40:33 Everyone likes Physics one because it's like all it's easy. I throw to
40:36 . It goes up and here comes . You know, I can hit
40:38 deer or whatever it is. Physics two is circuits which can be
40:45 confusing and it's optics which can be confusing. Alright. And part of
40:49 optics things is how do I bend ? That's if you ever wondered why
40:53 I take physics to if I'm going medical school. So, you understand
40:57 the eye works? All right. , we're bending light and what we're
41:03 to do. We're trying to bend in such a way that it gets
41:05 a specific point in the back of eye. Alright, vascular tunic.
41:14 outer tunic real simple helps maintain the of the eye protective allows light to
41:18 in, highly highly vascular lies. the name. All right. This
41:23 where all the blood vessels are gonna located. All right. This is
41:26 the intrinsic muscles of the I. . Remember extrinsic allows the eyes to
41:31 the intrinsic muscles of the I allow to adjust how much light is getting
41:36 the eye. So, the three include the core. Oid the silly
41:39 in the iris. The iris is where the smooth muscles are located to
41:44 the amount of light that's coming Those aren't the only intrinsic We'll get
41:48 the others here in just a There. They are right there.
41:51 , the chloride. That's the easiest . So, you can see here's
41:54 is all over the place. It all the way around, basically wraps
41:58 about two thirds of the eye. is all the blood vessels.
42:02 so this is how you provide the to the I uh there's also melanocytes
42:07 there. So that absorbs light. the idea is I can't shine light
42:11 MySQL Ara and see it because the and the pigmented layer in the next
42:16 are sitting there absorbing the light. light only really has one path into
42:21 eye, through the cornea. now, the silly everybody's It's this
42:30 right here. It's an extension of core oid, right? So,
42:33 can see it on either side. ? There's two parts to the silly
42:37 . There's the Salieri muscles and the process. The Salieri muscles are attached
42:42 a ligament are a series of ligaments called the suspense three ligaments. You
42:47 see them being represented here, Those are supposed to be the suspense
42:52 ligaments. And what they're doing is attached to the lens of the
42:57 All right. The lens you guys work with cameras other than ones on
43:01 phones. All right. You have lens and what you try to do
43:05 you're playing with the lens, you're . All right. So, what
43:10 gonna do is ancillary muscles play a in changing the shape of the lens
43:15 tugging on these ligaments, and it the lens to change shape so that
43:19 can focus near or far. All , So, that's an intrinsic eye
43:25 . The sill area process is responsible producing a quiz humor. All
43:31 Which is a fluid that contains all of stuff. We'll get to that
43:34 just a moment. So the fluid makes up the acquis humor is made
43:38 the celery process last is the iris you look at somebody and say,
43:43 goodness, your eyes are beautiful. someone's ever said that to you.
43:48 they're talking about is they're talking about iris, right? That's that muscle
43:53 colored all right. And basically, two groups of smooth muscles.
43:58 one that causes dilation, One that contraction. And so that changes the
44:04 of the hole that's found uh in midst of it, which is called
44:08 pupil. All right. Now, you're looking at it behind your thinking
44:11 , what does it look like? pupil is the dark dot in the
44:14 of your eye. All right. why is it dark? Well,
44:18 that is actually the back of your . You're looking into somebody's eye.
44:22 you say, I'm looking deep into eyes. You literally are looking deep
44:26 their eye. The thing is, light goes in, it doesn't come
44:30 out. And so you can't see . Is like looking into a dark
44:34 . All right. There's nothing there see because it's all dark lights being
44:38 , Right? But the muscle that that whole that is your iris.
44:45 . And so that's the thing that's to change in terms of size.
44:48 here we are with the eye here the pupil. Again, there's a
44:51 time pupil basically you're looking into the . It's not black because of anything
44:56 other than lights bouncing back at All right. The two muscles that
45:00 up the iris are the sphincter The dilated pupils. The sphincter papillae
45:06 the circle circular one. It contracts makes the pupil smaller. This is
45:12 parasympathetic innovation. The dilator is is round muscle, and it causes the
45:21 become larger. It's when that's the . This is under sympathetic innovation.
45:27 do I remember this? All When you are under sympathetic, the
45:33 response, so fight or flight. you're doing is you want to be
45:38 aware of your surroundings. And so happens is you dilate some more light
45:42 in so you can see better. ? You're more aware. It's a
45:47 response, and that's the way I it. Not the best way to
45:51 it, but, okay, so you go. So two Types of
45:58 muscle. one is in the silly . Right, Pulling on the lens
46:05 me to look deep in or near far. I think we'll go into
46:09 a little bit more detail. And we have the irish which allows the
46:12 of light into my eyes, I where we are. Good lens.
46:18 right, So, the lens is transparent structure. It's living tissue.
46:24 right. Even though it's not vascular , they have surrounding acquis humor,
46:29 shape of it determines the degree of of lights. That's refraction. That's
46:34 bending of light. And so the this works is those silly the muscles
46:39 the suspense three ligaments. Now, is a little bit difficult. All
46:44 . Think of a round structure. right. We have muscles that are
46:48 of wrapped around this around structures? the muscle relaxes, What it does
46:55 it relaxes goes ah and it pulls . All right. When the muscle
47:00 it moves further in. Okay. kind of see that. Oh,
47:06 reason that you need to kind of , that's because what's going on here
47:09 my muscle relaxes, it pulls it pulls on the ligaments.
47:13 So the muscles relaxing ligaments are the lenses stretched so it gets
47:18 What this allows me to do allows to see further, gives me far
47:23 , right? When my muscles what happens is they move forward,
47:28 ligaments relax and then the lens gets so I can see near. How
47:34 I remember this when you're reading? a lot of hard work, isn't
47:38 ? Right. Have you noticed that reading? You're like, it's
47:44 All right. When you're bored or , what do you do? Your
47:48 Rachel, aka? And your eyes out of focus. You're looking far
47:53 into the distance. That's how I it. Right? So, when
47:59 muscles relaxed, I have to see when the muscles contracted, I'm seeing
48:03 . But what it's doing is it's how much it's tugging on the
48:07 remember? It's see the look on face this way? Yeah,
48:16 So. Mhm. Yeah. So happened to the question is what about
48:24 now? You're getting into areas that complex. All right. So,
48:28 I want to show here just I think Well, I guess I
48:31 I mean it's we're dealing with the of refraction here. Let me just
48:34 the process of changing your lens shape called accommodation. So when you hear
48:38 word, so what you're doing is not accommodating correctly. That's why you
48:43 glasses. So, what you're doing you're bending the light appropriately so that
48:47 hits the right spot. Alright? what again what you're trying to do
48:50 you're trying to get the light to on a spot that's down here on
48:54 back of the eye. All And to do that, you have
48:58 bend the light appropriately. So, the lens isn't really it's not the
49:02 in the lens. It's actually the in the shape of the eye.
49:06 right. All right. Now, got to tell my horrible story.
49:09 right. You guys going into health ? Pay attention. I was a
49:14 man six years ago. Okay. was I mean, it's by by
49:20 very nature. So, you can tell this story is true. All
49:24 . I was having a heart problem the backs of my kids pills,
49:28 ? You know, it's like I see this like this six point
49:32 I can't read it anymore? I have glasses, optometry school said,
49:37 , free eye exams because they do roughly every year and I'm like,
49:40 right, I'm taking advantage because I'm spending money on my eyes. So
49:44 go in there and I go, know, go and get the eye
49:46 and stuff like that and I want keep your mind is going to miss
49:49 of you guys off who are young glasses In my entire life. I've
49:53 had 2010 vision. So here I , I'm going in there. So
49:56 a point of pride for me this kind of a, you know,
50:00 don't mean I got good eyes My my brother is legally blind,
50:05 ? Yeah, coke bottle glasses since was like eight. Alright. So
50:10 got all the good vision. He not. All right. I
50:13 I stole that, beat him up it and took his lunch money
50:17 Right? So I go in there they just said, Oh well you
50:20 your eyes are are no longer How did this happen? Well you
50:26 a stigmatism? I said, well does stigmatism when we're old?
50:32 I'm what now? So moral stories you're talking to your patients don't call
50:41 old. Mm. Yeah. it wasn't that bad. All
50:47 So what is refraction basically? It says that light travels at different speeds
50:53 different mediums. All right. And like the air is kind of our
50:57 . So we say it has a index of one. So, like
51:01 travels in a straight line, but it hits some other structure,
51:04 What it does is it bends, changes its speed and it bends and
51:07 that's a reflection refraction. All And we can see this when you
51:12 at a glass of water or something that, you can see it's like
51:14 looks like I've got this really weird or pencil stuck in the light or
51:19 the in the glass. And so purpose of the lenses to bend that
51:23 . But so is the cornea. remember we have fluids in our eyes
51:27 those bend the light. So each these things have a slight bend in
51:31 light. So your eye is modifying on all of these different things.
51:38 , a lens is always going to in the direction of uh well,
51:43 gonna bend based on what type of you're looking at. So concave one
51:47 the middle as to what it does that it bends light towards. I
51:52 this concave right here. It bends from the focal point. So our
51:56 point would be over here is at in our eye. But you can
51:59 here there's a focal point for the . So what is it doing is
52:03 light further away? Obviously our lens not like that are lenses more like
52:06 , You can see the focal points the back. And so what we're
52:09 is we're bending light towards the focal . So where do we want our
52:12 point? Our focal point is gonna in the back of our of our
52:16 . And so we want to do want to bend the light appropriately to
52:19 focal point? All right. So process of refraction is to make sure
52:27 happens now with regard to broken. like mine, right, because I
52:32 a stigmatism because I'm old. I don't feel old. Yeah,
52:40 don't think old. All right. think I can still do stuff that
52:44 guys are scared to do. I'd a bike often roof. Would you
52:52 at me like uh So I did fun. I'm not dead. I'm
53:00 dead yet. That's right. but it's really funny when you sit
53:04 in the when you wake up in morning and your whole body screams at
53:07 . That's when you know you're like, oh, if your body
53:10 already doing that, you need to exercising just saying, all right.
53:14 , um so, I want to kind of show you all the different
53:18 here. So, we have two . All right. Here's the first
53:22 . That's called the anterior cavity. below behind the lens. That's the
53:26 cavity. Alright, so we're really of focusing up here on the anterior
53:29 , posterior cavity has this gelatinous fluid the vitreous humor. All right.
53:36 purpose of this primary to maintain the of the eye to keep it semi
53:40 , basically it holds the retina in against the corduroy because it's not glued
53:44 there properly. Well, that's another one. When you go to the
53:48 , I'm looking at people with Do they look in your eyes and
53:50 make really snarky comments like, oh we gotta start watching that. Have
53:55 , Have they done that? Yeah, you're looking it's like my
54:00 one was you have an eye What? It's an I freckle.
54:05 an I freckle looks like a real but it's in your eye.
54:09 So is it dangerous? No, just have to watch it.
54:16 I have a friend who last year like, I had a wrinkle in
54:20 eye. In other words, the has slightly separated and and there was
54:25 potential for it to actually tear So he wasn't allowed to do
54:30 I'm like, I'm not even allowed drive. But you considered home and
54:36 at things on your computer, It's like yeah. So how is
54:39 any different than anything else? I know. It's just I'm not supposed
54:42 do stuff. I get to go him in two weeks. Sounds like
54:45 scam to me. I don't All right. Anyway, so that's
54:50 does it hold up against the Polaroid apparently not glued on right. And
54:54 the other thing is that it transmits . So you can see it's clear
54:58 so light can pass through it. it's a liquid. So it's going
55:00 bend the light just a little I think of a slide.
55:03 The next one that shows that um so that's posterior cavity. Sorry.
55:07 , in the anterior cavity we have acquis humor. Remember? It's being
55:10 by the silly everybody. So, basically being produced down in here.
55:14 what it does that washes over the here, the posterior chamber, and
55:19 it scoots out into the anterior And if you look carefully, you
55:23 see a little tiny dot right Do you see the dots? That's
55:28 canal of slim. You don't have identify it. It's just such a
55:33 name. I have to say Canal Ashlyn. Alright. And
55:37 Uh for people who have um crap , I'm liking the thank you
55:45 What's happening is that gets blocked And so the proteins and stuff that
55:49 in the uh in the acquis humor basically accumulating. And that's what actually
55:57 starts becoming clouded and becomes a solid . So canal of slim but not
56:05 you can do once canal slim gets up. All right. So,
56:09 is really again, you don't need see these. I mean memorize
56:13 Anyway, I'm just trying to pointing what we're trying to do is we're
56:15 to focus light down here to the centralist. Alright, so we'll see
56:21 word phobia, but it's in the of the phobia is the phobia
56:24 That's where the most cones are actually . But you can see that when
56:28 comes in, it hits these different and each of them cause it to
56:32 a little bit more. And so how we're getting the degree of bin
56:36 we need to because each structure has own refractory index and causes a certain
56:41 of bend. So pretty complex All right. Third layer.
56:49 we had the tunic. Right? mean, the fibers tunic on the
56:54 Vasquez tuna coming inside. Right. now we're going to get to the
56:58 that actually does stuff Well, stuff care about which is the retina,
57:04 innermost tunic. There's two layers to . All right. We have the
57:08 layer over here. All right. here you can see the core oid
57:12 pigmented layers right up against it. is an area that produces vitamin
57:17 And actually we're not produced by it vitamin A. And actually modifies.
57:22 literally takes it and clip clips it and a half. And what you
57:25 up with is a molecule called retinal retinol is the molecule that allows you
57:29 see. All right. So, we talk about vitamin being so good
57:33 your eyes and stuff really. What saying is that it provides the the
57:37 that's used to make the retinol that your eyes to do what it
57:41 All right now, it's a pigmented , meaning there's lots of pigment in
57:44 . And the purpose of pigment is absorb light. And so when light
57:47 in, so this is the direction light moving, right comes in through
57:51 cornea, it hits that retina. right. And if it doesn't hit
57:56 of the receptor cells, it's gonna that pigment layer and that light gets
58:00 . It doesn't bounce back out. hits that and it stops light coming
58:05 this direction. So, just pretend to get in like this. It's
58:08 to hit that pigmented layer. So doesn't come in. You don't see
58:12 that way. The only way light in is through the cornea.
58:16 is that 100% true. Now, I get a light and pressed up
58:20 your square, do you think your are going to detect it?
58:23 but you're not gonna be able to anything. You might see blood
58:26 So, again, people have had when they're sitting there shining that light
58:29 your eyes and you can see all blood vessels and stuff. It's kind
58:32 wicked, right? You know, looks like dried mud is how I
58:37 it looks like all the blood you know? But yes, you
58:41 still see stuff like that, but not actually seen what we're interested in
58:47 the most part is this stuff right . This is the neural layer.
58:50 can see there's different types of cells color coded for us. There's photo
58:54 cells. The photo receptor cells are ones furthest from the light. And
58:58 they're going to do is if they up light, they're going to then
59:02 their signal along a series of neurons then are going to be projected up
59:06 the visual cortex. All right. , there's different layers of cells.
59:11 , what we're gonna do is we're take that light energy and transducer it
59:14 those action potentials. Well, greater than action potentials. Alright,
59:19 these are the cells that were most in. I want to point out
59:22 there's other cells as well. All . So, our starting point is
59:26 photo receptor cell and this is where going to focus most of our
59:30 All right. These are your rods cones are the outermost layer.
59:33 they're the furthest from the light. have to life has to pass through
59:36 the other layers to get to the receptor cells. Their job is to
59:41 that light energy into a signal. right. There are very, very
59:47 cells. They are not large enough produce action potentials. So, everything
59:50 gonna do is gonna be done through greater potential. The next group of
59:54 or the bipolar cells. That's the cell here. Alright, So,
59:58 lie between the photo receptor cell and gang land cell which is going to
60:01 on to the visual cortex. Their job is to take that information
60:09 the photo receptor cell and determine what to be sent forward. Now,
60:14 of the things that we're going to here is there's a convergence of photo
60:18 cells on bipolar cells. What that is is that there's fewer bipolar cells
60:23 there are photo receptor cells. we're doing is we're taking information and
60:28 focusing it inward. And then the layer of cells of gangland cells.
60:33 fewer cells. So, I'm gonna up a number for you.
60:36 We're going to start off with 100 receptor cells. All right. And
60:40 we're going to go say 10 bipolar which then converge under one ganglion cell
60:48 then that one ganglion cell then represents receptive field for all those photo receptor
60:56 . All right. Kind of makes . So, if I stimulate this
61:00 receptor cell over here, this one here, because they're all converging in
61:04 that one gangling. So, it matter which one I activate. I'm
61:08 that one ganglion cell. That kind makes sense. All right.
61:12 what I just told you. Isn't true, but that's our starting
61:15 I want you to do. I want you to understand our starting
61:18 All right. So, the ganglion is the innermost cell. Right?
61:25 the one that's nearest the source of . Its job is to send information
61:29 to the visual cortex and really what axons are. That's a neural
61:34 Right. The axons form the optic . All right. Graded potentials.
61:41 cell, small cell graded potentials. cell that then performs a nerve which
61:48 basically a series of accidents, action in the ganglion cell. The other
61:54 cells, these are the horizontal cells the immigrant cells. So, you
61:57 see here here is the horizontal cell between the photoreceptors bipolar. Here's the
62:02 cream sits between bipolar and ganglion These are cells that modify the
62:06 All right. So, remember how said, the brain doesn't actually get
62:11 raw signal. There's some modification taking . There's a lot of modification in
62:16 eye. And so, what these little cells in between do is they're
62:20 there trying to figure out how to the signals and what they mean.
62:25 so, they're making modifications along the adjusting how that signal is really hit
62:31 hit your brain. So, your is already altered even before it gets
62:35 the brain. That makes sense, of. All right. Now,
62:41 some other cells that your book I just want to mention them to
62:45 . So, remember I said we ganglion cells or ganglion cells there's also
62:49 are called photosensitive ganglion cells. Your who wrote that chapter was really excited
62:54 bring this up because no other textbooks about these. All right. They
62:57 discovered a couple of years ago And mean I teach about them in my
63:00 fist class because I do have students are gonna be optometry and they're really
63:05 . They're a ganglion cell that actually detect light. All right. So
63:09 was one of the reasons why they really excited when they discovered these
63:13 You've probably I'm not gonna remember the of the disease state. It's blind
63:19 . That's I'm not going to know it's called. But basically even if
63:24 blind and you can't see light, have these ganglion cells that can detect
63:30 . And so what happens is is actual body is dependent upon the light
63:35 it actually reflects on. We were a little bit ago about Seattle and
63:39 people in Seattle you know, has highest rate of depression around the
63:44 All right. It's like twice you it was twice the U.
63:48 Right? And the reason for that because Seattle's always overcast and no one
63:51 gets any sunlight and everyone's miserable all time. And so life sucks.
63:55 get down here into the deep There's lots and lots of sun so
63:59 sun that we stay indoors all the . Right? But we're mostly happy
64:04 mostly right go down even further You've heard the song by jimmy Buffett
64:10 in attitudes because of changes in latitudes north you go the more depression lower
64:16 the lower in the country go toward equator. Better. The attitude that
64:20 has to do with the amount of you get. These cells are the
64:24 that detect sunlight. All right. what they do is they communicate with
64:29 Peniel gland and are responsible for setting circadian rhythms. All right, That's
64:36 of cool. And so, you how if you if you you start
64:41 with your circadian rhythm, you know you go to sleep and when you
64:44 up and stuff like that, you noticing that your behavior changes,
64:48 It's because of the amount of light you're getting your body's awake. It's
64:52 wait a second, I'm not getting the sunlight. What do I do
64:54 this? All right. So that's the photo receptor ganglion cells do.
64:58 have their own photo responsive pigment and they respond to the sunlight and you
65:04 need to be able to see to these cells do what they do.
65:09 so there's a condition among blind people their days kind of start getting off
65:15 because while they're not seeing the their bodies detecting light and they and
65:19 body is trying to respond to the of light that they're detecting. All
65:24 . So basically act on the penny land. All right. And then
65:28 other one I said is the retinal epithelial cells. They basically contain that
65:33 . And so that's the one I describing just a moment ago. They
65:36 light and that's why you see that in the back. Yes. So
65:43 got like oh I don't know like minutes here. I'm probably not gonna
65:46 through everything here. That's okay because gonna talk about a little bit
65:50 But I want to this is where want to spend our real time is
65:53 in the rods and the cones. now, rods we have one type
65:57 rod in our body. It's called rod. All right. You can
66:00 why is it colorado shaped like a And then you can see the other
66:04 of cells. These are photo receptor . Both of them are cone
66:08 There's three types. All right. have special names form. We typically
66:12 them for the peak at which they're stimulated by what wavelength of light.
66:17 we refer to as either red, or blue, but that's not what
66:21 detect. They don't just detect They don't just detect green. Just
66:24 blue. That's their maximum stimulation in particular wavelengths. Some textbooks refer to
66:29 as S. M. And That refers to the length of the
66:33 small, medium or large. And so I don't even think I
66:36 do that with you guys. I when I maybe later, you
66:40 But I'm never going to ask you are the wavelength and stuff. I
66:43 want to understand. They detect a of light and they're maximally stimulated at
66:48 that range someplace. And that's where get their name. The cones are
66:52 for color vision, whereas the rods most of their role in vision in
66:59 dark. Okay, so this is like a night vision now where we
67:04 them are very, very different. , well you can see structurally they're
67:07 . They have these structural, you see there's a series of like pancake
67:11 structures in there. These are little membrane bound discs. But in the
67:16 you don't have them. It's actually membrane is actually folded on itself over
67:20 over and over again. So it's of like a cone that's been weirdly
67:24 . Alright. The artist didn't do good job here. All right.
67:28 um what we have here is where look at them. If you take
67:32 retina, remember we said the retina basically wrapped around the eye. On
67:35 inside. It covers about two thirds the eye. You don't have them
67:38 the front. Could that be And so what you do is like
67:41 ? But if you were to flatten out and say, where do I
67:43 rods? Rods are primarily found on periphery. Alright. Whereas cones are
67:49 localized at the back of the at the phobia. All right.
67:53 specifically at the phobias and Charles and have a slide on the next one
67:57 will show this in kind of a representation. Right? So if this
68:03 is responsible for seeing color, we see color best when there's lots of
68:09 around. And so this is primarily day vision. This is primarily for
68:14 vision. They're very, very sensitive low levels of light, but they
68:18 provide a lot of acuity. All . To just kind of understand what
68:22 means. Think about when you wake in the night to go to the
68:25 . I know many of you don't that, but just imagine that you
68:27 right, Right. You don't turn the light, right? What do
68:30 do? I mean, you're laughing it's like you're looking at the old
68:33 who gets up in the middle of night, right. If you look
68:35 the room, can you see anything it's dark? Can you You can
68:40 kind of shapes right over in the over there. That's where all that
68:44 is that you've been piling up Or might be a monster. You don't
68:49 . It's it's just crouching over You have you have to turn on
68:52 light so that you can see. you you're like, well, that's
68:55 I put the laundry. You know all the furniture is because you can
68:58 their shapes roughly. Right? But can't see the details of everything.
69:03 , that's the example of what rods is they allow you to see,
69:07 know, in low levels of some general structure, but they don't
69:12 you details. The cones on the hand, you need lots of
69:18 but when they get stimulated, you see detailed very, very well.
69:21 right. Now, The last thing wanna point is convergence. Alright,
69:26 I mentioned the conversion. I said you have 100 cells going down to
69:29 going down to one. Really, I was describing their what rod cells
69:33 they have a high degree of You can have lots and lots and
69:37 of rod cells and they converge on bipolar cells, which converge on like
69:42 ganglion cell. All right, cones Cones are like a 1-1-1 ratio.
69:50 ? So, if you stimulate one , you're stimulating one bipolar cell.
69:55 gonna see here. That's even It actually could be to bipolar cells
69:58 then what you're doing is you're going to one ganglion cell or to ganglion
70:04 . All right. So, there's low convergence and all these things have
70:09 meanings. This is what all these couple slides really are trying to do
70:12 trying to describe what each of those mean. So, here, this
70:15 trying to show you the density. , if you look at the back
70:19 the eye. All right. There's region called the optic disc. You
70:23 . You probably played with this when probably in fourth grade or fifth
70:26 Get the piece of paper. Put dot on there about three inches
70:30 You put another dot, you focus one dot and then you move the
70:32 of paper back and forth and the dot disappears. Alright. You found
70:38 blind spot. That's where the optic is, basically that's where there are
70:42 photo receptor cells. That's where all accents of the gangland are going
70:45 And so they don't have a photo sitting over that because it's jam packed
70:51 of axons. So that's that's the disc. That's the blind spot.
70:56 right. So it's immediately located. can see you're looking at the back
70:58 the eye. You can see there's optic disc can see blood vessels coming
71:02 of the same spot where the optic is? Alright, that's easy.
71:05 that's just a little tiny spot. that's okay. We can fill it
71:08 because have you noticed that when you around? You don't see like this
71:10 space over here? That's always Right? It's your brain kind of
71:14 in this What what expects to be ? Uh huh. We have this
71:21 . Yeah. Don't we wish we the macular Lutetia. All right,
71:27 Atiyah is basically just the area directly the pupil. So, if you
71:31 to take a line and go straight through the cornea, through the back
71:35 the pupil, you'd go and hit macular Lutetia. All right. That's
71:39 the light is all being focused. your focal point sort of because there's
71:43 spot inside that that's even more And that's the the the phobia central
71:50 . Alright, how do I look this? Or think about this?
71:52 about a bull's eye. All Think about a dartboard. You've got
71:56 dartboard. Here's your retina, flatten out. Now. You've got a
71:59 board in the middle of the dart . You have the bull's eye and
72:02 you have in the center of the eye. A no, no one
72:06 play darts, guys are in Come on, get out. You
72:12 the double bull's eye. All If you've learned how to play
72:20 Sure. All right. May have do a field trip over to pinks
72:25 something. I don't know. All . Anyway, so the bulls
72:30 you have the double bull's eye and the middle of the bullseye there's another
72:33 circle. That's the double bull's All right. So think of the
72:38 tia as your bulls, I think the phobia centralist as the double bull's
72:42 . And with this little map on bottom is trying to show you like
72:45 all these photo receptor cells. little blue ones represent the rods,
72:49 big green ones here represent the If you were to flatten out the
72:53 , you see there's lots and lots rods, very few cones. But
72:57 you move into the phobia centralist, you have are cones. Okay.
73:05 this kind of makes sense in terms how you see stuff when you look
73:09 something, Is it nice and Even when you have glasses on?
73:12 and clear? Yeah. All Here's a trick for some of you
73:16 take a look at your piece of or something that's in front of
73:19 All right, for that. You've put stuff away, you're gonna be
73:22 . No, look at it, look at something and focus on
73:26 Look at it very, very You see it clearly without moving your
73:29 . Look at the rest of the . Is it blurry? Do you
73:32 to move your eyes around to try see what that blurriness is?
73:36 what you're doing is you're eyes are saying um I want to look at
73:40 now and I want to make it . I can kind of generally see
73:42 this page for example, that there's right, but I can't read the
73:46 words, I know what's there, if I want to see what the
73:49 words are, I've got to focus and so I'm gonna move my eye
73:54 that the light is pushing right back the focus and trials where all my
73:58 are located. So the focus in is the focal center of the
74:04 And when we come back we'll deal dark adaptation. I like that
74:09 I should talk like that more All right. We will see you
74:14 Tuesday. Have a great day. , sir, he was
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