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BIOL 2301 Human Anatomy & Physiology I - BIOL2301_lecture20_1107
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00:00 10 test outstanding. So I don't numbers for you this morning, but
00:03 everything you need to know about um, about your grades.
00:08 I sent in that, uh, , announcement last night. So,
00:12 , if you haven't read the if you just read like a third
00:15 it, go through the whole Um, it's basically the advice I'd
00:18 you if you came in and sat front of me. So,
00:22 you know, willing to talk to about your grades, willing to talk
00:25 you about, uh, decisions you to make. If you have decisions
00:28 need to make. Um, but would like you to actually come informed
00:31 you come and talk to me. , uh, with that we have
00:35 classes left. Yeah, some of should be really excited about that.
00:40 think all of you should be really about that. I'm excited about
00:43 That means Christmas is coming. Thanksgiving around the corner. Food is to
00:48 eaten and stuff like that. And we're gonna do for the rest of
00:52 semester is we're spending most of our , if not all of our time
00:55 the peripheral nervous system. And what gonna be doing is we're gonna be
00:59 at how signals are being sent up sent down how we're receiving specific types
01:04 signals. And so our starting point is really to kind of talk about
01:07 big picture right? To give you idea of what receptors, what do
01:11 do and how do they work. then from there, we're gonna start
01:15 into the special senses and special senses the sense of sight, the sense
01:19 smell, the sense of taste, sense of hearing, the sense of
01:23 . And then after that, what do is we go into the
01:25 Uh I think we go in the systems. In other words, how
01:28 send signals back down through the peripheral system. And then finally, we
01:32 up with um the autonomic nervous system . I think that's how it works
01:35 . There might be a flip flop there someplace. And so this is
01:39 of our starting point, right is is a sensory receptor? What are
01:43 ? What are receptors? What is stimuli? These are terms that you're
01:46 hear over and over again and simply a sensation is a conscious awareness.
01:52 we go. Conscious awareness of incoming sensory input. So this room is
01:56 light, you know, I I can declare that it's kind of
02:00 in here. And so that would an example of its sensation, it's
02:04 awareness of what's going on around me being perceiving or understanding it.
02:09 right. So this can only happen that information finds its way to the
02:14 cortex. And then that information is pushed on to other parts of the
02:19 cortex, like the frontal lobe. that sense of I am, I
02:23 therefore, I am. So that's we're talking about here. All
02:27 a receptor simply is that thing which to a specific stimulus and in initiates
02:33 sensory response. All right. And these receptors have varying degrees of complexity
02:40 them. So you'll hear the term in multiple ways, it can refer
02:45 a molecule. So we can talk a receptor on a cell,
02:49 Or we can talk about the cell as being a receptor cell. And
02:53 we'll just call it a receptor, ? Because we're lazy and that's just
02:56 we use our language. And then have more complex receptors like your eye
03:01 a bunch of cells that work together you to detect light. And so
03:05 might refer to the eye as a . So any type of of something
03:10 receives some sort of stimulus, whether be a single molecule or as large
03:14 an actual organ counts as a All right. But you'll usually be
03:20 to know based on context. All . That's really how it is.
03:24 right. And finally, what is stimulus? That's simply the change in
03:26 sensory information that our receptors are Now, you're sitting there, if
03:30 look up and you look at this and you're saying we're not seeing any
03:33 in the light, it's always But what you're doing is those light
03:38 are hidden that receptor and activating And so it's that activation is the
03:42 that you're detecting. So that's what referring to. And I'm just using
03:46 as an example here. All So with that in mind, what
03:51 receptors doing well, receptors are changing energy form into something your brain
03:57 And let me just see if I make you understand this in a
03:59 really simple way. If I cut hole in your head, let's just
04:03 it right back here in the occipital . And let's put a flashlight in
04:07 back of that hole pointing at your . Will your brain know that light
04:11 shining on it? No. Well, one you don't have receptors
04:17 your brain to detect light, But the other problem is is that
04:21 is a form of Electromatic electromagnetic It is a form of energy that
04:27 brain does not use as a form language or communication. What language does
04:33 brain use? Mhm Nerve signals, potentials. That's what we're looking
04:41 And so what, what all these in your body are doing? Are
04:45 one form of energy into a different of energy. In other words,
04:49 turning light energy into electrical impulses. taking these chemical stimulants and turning them
04:55 electrical impulses. So it's this that receptors are responsible for. So
05:03 brain cannot perceive until that language is is converted into the language of the
05:09 or the central nervous system, So we refer to them as being
05:14 . Now, I have a pure chemical energy because really what you're doing
05:18 when you're talking about a a basically it's electrical and then it releases
05:22 chemical at the end. All So technically, there is a chemical
05:26 , but we're just kind of going blah blah and just say it's colored
05:29 . All right. Second thing receptors establish and maintain a resting membrane
05:36 You're like, oh my goodness. we coming back to this again,
05:39 whole resting potential stuff? Yes. how I said, this is foundational
05:45 everything that we're moving forward, everything the nervous system, everything about the
05:49 , cells have to have a resting potential. So you establish that resting
05:54 potential and then you move away from . And when you move away,
05:57 when you get the signal that moves . All right. So the receptors
06:02 a certain modality that they detect. right. And so modality is a
06:08 word for they detect something we're going see different modalities in here in just
06:11 moment. And so what we have modality gated channels. Now, we've
06:15 about different modality gated channels already. you think of one type of modality
06:20 channel that we've discussed at least once the class, if not 1000 times
06:27 receptor. But which type? So think about the action potential, there
06:30 two types of gated channels on One was voltage, what was the
06:34 one Lagan or chemically gated would be . So the voltage and the chemical
06:42 be a modality. All right. it's a different mode. It's just
06:47 I'm detecting something. All right. we're gonna have specific types of modality
06:51 channels in the plasma membrane depending upon types of cells and the type of
06:54 that we're dealing with. All So we have receptors are gonna be
07:00 down into different groups and we're gonna different types of groups being used here
07:04 describe the different types of receptors. have the general senses and we have
07:07 special senses. So the general sense is very, very simple in
07:13 We refer to them as either being sensory or visceral sensory. All
07:17 So notice we're not talking about we're talking about sensory. So we're
07:21 information in, we're detecting around So, somatosensory is gonna be de
07:26 things that are occurring at the level the skin or things that are occurring
07:29 the muscles. All right. So what SOMA refers to. All
07:34 So skin and when we're talking about , we're talking about tactile.
07:38 since touch, that's pretty simple. then the other one, if it's
07:42 the muscles, what are we We're looking at stretch and movement.
07:44 am I putting my arm in the place? Am I putting my leg
07:47 the right place? All right. I sitting upright and holding my body
07:51 the position that I want to be in? So those were those Golgi
07:55 uh receptors, for example, would an example of that. All
08:00 the visceral, on the other is gonna be in the walls of
08:04 viscera, which we said it already your guts, right? So your
08:08 and so these are gonna be looking say things like temperature, chemicals,
08:12 pain, so on and so All right. So that's what we're
08:16 of focusing today is gonna be on things right here and these things up
08:20 , the special senses. On the hand, these are very, very
08:23 sense organs. All right. So talking about and I've already mentioned them
08:28 , I don't know if I said sense of smell. So uh we
08:31 Gus Station that's a sense of all right, olfaction, sense of
08:37 , audition, sense of hearing, , sense of sight. And then
08:42 weird one that sits over on the is equilibrium. That is your
08:46 your ability to detect the position of body in space, the position of
08:50 body and in general during movement, on and so forth. So the
08:55 that you're sitting upright is a function your equilibrium. All right. So
09:00 is what two or three lectures are actually, I think it's three or
09:03 , you know, three lectures I is on this. So this what
09:06 is all about? So we can receptor. Is it a uh special
09:13 or is it a general sense? then what we can do is
09:16 all right. Well, um where this sensation come from? What are
09:20 detecting? Are we detecting things from the body? Are we detecting things
09:24 the side of the body? And where these names come from?
09:27 that's external surface. So we're talking tactile receptors on the skin. Uh
09:32 also includes your mucus membranes because remember cavities that enter into the uh through
09:38 open spaces of your body. Um those are on the surface, they
09:43 don't appear to be on the They're just hidden inside you. So
09:46 mouth, the nasal cavity, uh urethra, the vagina, the
09:51 these are all openings into the ear canals. You might have,
09:56 don't have mucus membranes, but the ones have mucus membranes. All
09:59 So those are detecting things on the surface exteroceptor interceptors. On the other
10:07 , are gonna be internal organs so we, we're going again back to
10:11 and somatic sensory. So notice when say here, we're talking about
10:16 When we're talking somatic, notice the is up here and then when we're
10:20 about visceral, that's just your guts . All right. So these are
10:23 words to help you understand where I'm , right. So if you're
10:28 oh, we're looking in interoceptor, , you should immediately think,
10:31 I'm talking about things inside my That's a, that's all this
10:36 And then finally, here are some . Now, this is not a
10:39 list. These are the most common of, of, of receptors based
10:45 modality. All right. So we thermo acceptors. We're gonna talk about
10:49 in a little bit here. These the things that are sensitive to changes
10:51 temperature. All right. It's not heat, it's just changes in temperature
10:56 acceptors. That's an easy one. detect chemicals. All right. We
11:01 meccano receptors. Mechanoreceptor are simply those that respond to changes in the shape
11:06 the cell that has those particular types receptors. So we're talking about touch
11:11 pressure and vibration and stretch, You ever been pinched is pinching
11:20 We'll see how long it takes you to answer that question. No.
11:23 . No, it's not fun. hurts. All right. It gives
11:26 a sense of pain, right? it's one of those cute ones on
11:30 butt. And you're like, all , see, now we'll get,
11:34 we got a different sensation going All right. But the idea here
11:38 that, that pinch is actually I'm a cell and I'm stretching it and
11:42 sending that signal. That's would be example, mechanoreceptor. But there are
11:46 types of mecano receptors. Barrow receptors with pressure Osma receptors, which is
11:52 weird because it deals with the uh difference in concentration of, of so
11:57 solution. So it's looking at How much salt do you have?
12:01 much uh is typically what it's looking salt? All right. Um
12:07 this is the position of your body space so that you know, so
12:09 can already start seeing if I think the special senses, equilibrium uses what
12:14 of receptors it uses propio receptors, are specifically mecano receptors. All
12:21 And so one of the things we're ask is how does it do
12:24 You know, if you're talking about the shape of cells, how do
12:27 , do you change the shape of cell to determine whether or not I'm
12:30 upright? OK. And then we no C seor if you see this
12:34 and you're like, I have no what the root of that is.
12:36 the same root that gives us right? So something that's stinky,
12:41 your nose wrinkle, that would be . Noxious smell, so nosy,
12:47 , noxious receptors and no c acceptors with painful stimuli. And so there's
12:53 lot of different things that give rise pain and what is pain? Let
12:56 just ask real quick. What is ? Anyone know? Yeah. Is
13:00 weakness leaving your body? Some people said that people who are athletes have
13:07 heard that at least once in their . Right. No pain, no
13:11 right now. Pain is basically your telling you stop doing that or you're
13:15 cause harm to it. Don't tell to your coaches because you'll find out
13:20 that they'll see where the limit of pain is. All right. So
13:25 we're looking at is, hey, damage. Think it's something chemical that
13:29 cause harm to your body that causes . Anyone here can think of something
13:34 you may, might eat that causes . Anyone here likes spicy food.
13:42 , here's some, some of. . Uh huh. Yeah. Done
13:45 ghost pepper challenge. No, Trinidad . Mm. I'm not talking a
13:54 bug. I'm talking a little tiny . All right. When you eat
13:59 food, what is the sensation? get spicy food? I should say
14:04 get a sense of burning, And what do you say it
14:09 My mouth is on fire, So that would be an example of
14:14 , but that's a chemical that's not , but you can also have
14:20 right? If I put my hand a hot stove. Does it
14:24 Let's do something more realistic because we're three year olds. Have you ever
14:28 on a Houston sidewalk in the middle the summer without shoes? Right.
14:32 first three steps. And then all a sudden it's like, nope,
14:34 , nope, nope, nope. . Yeah. Pain. Ok.
14:37 , and then mechanical damage, we've talked about pinching. So, these
14:40 just examples. Right. And we probably come up with about 1000 other
14:44 . All right. So we can based on modality. We're gonna tell
14:49 a receptor based on which direction it's . Is it detecting the inside of
14:53 body or is it detecting things from outside of my body? Is it
14:56 special sense? Is a general And lastly, we're gonna look at
14:58 terms of structure. All right. this is where anatomists get all excited
15:02 like, oh, something of So what do I have? I've
15:05 encapsulated versus un encapsulated. So something is wrapped up and something that's not
15:10 up. That's what it really means . All right. So over here
15:14 an example of an un encapsulated You can see those are the receiving
15:19 of the of the receptor cells. that would be the dendrites. Notice
15:22 dendrites come together form a long process then the cell body is sitting over
15:27 on the side. All right. this is a very common feature because
15:32 we're talking about sensory receptors, we about the dorsal root ganglia and the
15:36 bodies being located in there. And why because there are these uh pseudo
15:40 polar. But what you can see is all these little dendrites are converging
15:45 forming that process, but they're they're detecting different parts of the environment
15:50 which they're located. So that would an example of an un encapsulated sitting
15:55 to it. This would be an of an encapsulated. The dendrites are
15:59 up or the dendrites singular. It be either or are wrapped up and
16:04 in some sort of connective tissue or sort of structure. Now, the
16:09 for this is multifold and really what boils down to is that it makes
16:13 larger receptive field. So I can a larger area. All right.
16:20 other thing that we can do is can do some kind of weird
16:23 We can have a sensory cell associated the sensory neuron. So the neuron
16:29 is not the receptor, the receptor a different type of cell sitting off
16:33 the side. And so the cell the one that detects the change and
16:36 sends a signal to the sensory which then sends a signal upward.
16:41 right. So this would be a or sensory cell coupled type of
16:46 Whereas another is, well, here have my uh uh dendrites, there's
16:52 cell body, this is one long . And so this is different than
16:56 you see here. Um It's a type of structure. So we have
17:02 varying different types of sensory cells and they look at. And so when
17:06 look at these different systems, you to keep in mind kind of like
17:10 am I looking at? But in most simple form, we're gonna see
17:15 versus that. When we start getting special senses, we're gonna start seeing
17:20 over here. Another thing you can is you can look at a receptor
17:27 ask the question, is it a receptor or is it a phasic
17:31 Now, this gets a little bit complicated. And what you're asking is
17:34 when I stimulate the cell, how it respond? That's, that's the
17:40 . All right. So a tonic is constantly responding to a stimulus and
17:45 constantly responding at a, at a rate. All right. So what
17:50 saying is that no matter how often stimulate this thing, it's always producing
17:55 result. Now, an example of would be the receptors that are found
17:59 the muscle of your back to maintain posture, right? They are constantly
18:04 the degree of stretch in the muscles they're constantly sending signals up to the
18:08 to tell the brain how much stretch occurring so that you stay in an
18:12 position. All right. So it's a constant signal. Just I'm just
18:17 sending information never stops. It's like , it's just constantly sending the
18:22 All right, a phasic receptor. the other hand, is one where
18:27 undergoes a very rapid adaptation. All . And what a rapid adaptation means
18:33 that it only signals when changes occur the stimulus. All right.
18:39 I'm gonna, I'm gonna give the here, but I'm gonna point out
18:43 in giving the example. All So just watch. All right.
18:47 the example would be the fact that feel you don't feel your clothes touching
18:52 body until the clothes are not touching body. Now, once I said
18:57 , touching your body, you can feel your clothes touching your body.
18:59 up until that moment, you didn't your clothes because your brain said,
19:04 um this morning I put on my , I felt me putting on the
19:08 and instead of my brain getting the all day long saying clothes you're touching
19:12 , clothes are touching you, clothes touching you. That was unnecessary,
19:16 ? What was happening instead was your said OK, clothes are touching my
19:20 . And so now I can go my day until something untoward happens.
19:24 let's say you're walking and you snag shirt on a branch and the branch
19:28 your shirt off and all of a like clothes are not touching my body
19:31 would be something that your body probably to know. Right. That's the
19:36 . So that's the example of a receptor. Basically, it rapidly changes
19:43 that the stimulus doesn't cause uh a in the cell. Instead you detect
19:51 when the changes have occurred. So would be like an on, I
19:54 lots of really quick signals and then the change is off, that's when
20:00 get a lot of quick signals and that's it. No, nothing in
20:04 . All right. And this doesn't show that here, but we're gonna
20:08 a picture. I think uh I have one. I don't have a
20:12 one. I thought I had one you guys. Maybe I'll do it
20:17 way. Let's see if the black here. All right. So the
20:20 you look at one of these if you're sitting there going, I
20:22 understand what the hell I'm looking That's fine. All right. So
20:25 top basically is this, so you think about this as being off that's
20:30 on. This is a time. ? That's how you look at
20:35 So what it's saying is nothing's going and then stimulus occurs and now the
20:39 is being maintained and then it turns and now nothing's going on. That's
20:43 you'd read that. So it's binary versus on. All right. The
20:48 thing it's saying is look, if have a rapidly or if I have
20:52 non responsive or a tonic or what is in terms of action potentials,
20:57 see action potentials. That would be this the entire time till it turns
21:01 and then off, it goes So this is an example of tonic
21:06 on the other hand, would look this. All right. So only
21:15 I've turned it on and only when turned it off, would you see
21:18 , would you see the response? . So that's probably the easier way
21:23 see it other than the picture that showing up here. So these are
21:32 different ways that we manage signals going to the brain because you can imagine
21:37 have hundreds of thousands, if not of receptors throughout your body and your
21:43 has to process anything that's sent to , right? It has to decide
21:48 or not a signal is even important not. So there's me mechanations,
21:52 processes that are there to kind of through and make sure that only the
21:58 important signals are being the ones that processed. And this is one of
22:03 is having receptors, sending signals only it's necessary. Now, I used
22:10 word a little bit ago. It's a receptive field. A receptive field
22:14 simply the area in which the stimulus detected. So I'm going to use
22:19 , for example. So you can here, here's my uh long
22:22 there's all my dendrites and So wherever dendrites are, they are detecting within
22:27 area. So anything within that area that receptive field? Now, this
22:32 the picture of touch, every type system that we're looking at that has
22:36 sort of sense has a receptive All right, it's, it's just
22:41 the area in which I detect. for example, in your eyes,
22:44 gonna look at individual cells and each those cells detect light coming from a
22:48 location in your eye field. And we refer to that as being part
22:53 that receptive field. All right, sense of smell is detecting chemicals within
22:58 specific range. That would be the field. All right. Now,
23:03 regard to the sense of touch, is a possibility of things overlapping.
23:09 what you can do is if you to discern fine touch between crude
23:14 what you're gonna want to do is gonna wanna have more and more receptive
23:18 that are smaller and smaller. All . Now, this is kind of
23:22 cool little thing that you can do home. All right, you can
23:25 a P two pins really and take look at the edge. Uh,
23:29 tip of your pin. Is it of sharp? Is it kind of
23:34 ? Yeah, kind of trying to mine out here. I'm just
23:38 So you can get one of you get two of them, go
23:41 a friend who's willing for you to them. All right. All
23:45 You're gonna do this. OK? . So what you do is you
23:48 one pin and you put it at point and then you take the other
23:51 , put it at the other point then have that person not with the
23:53 and then walk that pin up and they feel only one sensation cause what
23:59 do, if you feel two you're in two receptive fields.
24:02 Does that make sense? And then you move that pin up, what's
24:05 to happen is eventually you're moving the into the first receptive field. So
24:09 going to only feel one thing, ? Now, on the arm and
24:14 the leg, you have very large fields because it's not particularly important to
24:18 what's kind of going on as long you know that like the arm is
24:21 touched and the leg is being that's probably good enough, right?
24:25 on your fingers and on your I mean, would you say that
24:30 things are how you touch stuff for most part? You don't use your
24:33 to touch people. Maybe you I don't know, see everyone's gonna
24:38 doing this. Now, this this is a lot of fun,
24:40 it on the back of their do it on their arm, do
24:43 on their neck. And what you'll is that there are different areas that
24:48 different size, receptive fields, the and the bottoms of the feet,
24:51 example, have very, very small fields. That's why you're able to
24:56 things. Like if you touch a ball, you can feel that it
24:59 not only round, but it is and all the unique characteristics that it
25:05 . All right, the larger the field, the less accurate the information
25:12 gonna be about that thing. All , you'll not notice things that are
25:16 bit more crude in terms of their . So, receptive fields are one
25:21 the ways that we detect or to the brain where things are happening and
25:25 the features of that are. But smaller the receptive field, the better
25:30 details you can get. Yeah. here's a fancy word that you already
25:37 the definition to. You just don't it. You'll see a word like
25:42 potential. A receptor PP A receptor is simply the greatest potential in a
25:48 cell. That's it. So it the ep SPS that are being produced
25:53 the receptor. That's it. Why do we call it a receptor
25:59 ? Because we like to torture freshman when they enter into college. What
26:03 you think? No, it's just saying, hey, I want you
26:08 know I'm talking about a receptor cell what's going on here. So when
26:12 receptor receives a signal? All So here's our receptor cell,
26:16 There is our fiber going up to nervous system. All right. So
26:21 stimulus comes along, activates the That cell is gonna release neurotransmitter to
26:27 the corresponding cell, the corresponding the epsp that's produced in that neuron
26:34 that neurotransmitter is the receptor potential. that receptor potential, that great potential
26:40 not strong enough to produce an action , then the signal doesn't move forward
26:45 your brain doesn't perceive the stimulation. if the signal is strong enough,
26:52 a strong enough receptor potential, you're get an action potential in the sensory
26:56 that then goes up. And your says, oh, I got stimulated
26:59 this particular point. So all that is simply the greater potential that's being
27:06 . Now, there's some other things are going on here that I'm trying
27:08 describe right transduction. So what did do? I took the stimulus,
27:11 converted it into a chemical signal that then gets converted into electrical signal.
27:16 that would be the process of Um Anything else up here that's might
27:22 of interest, not really. So potential is gonna be taking place in
27:26 sensory neuron pointed out there because we're information upward. So that's all there
27:31 to this. And lastly, and don't know why I use the same
27:35 here. Basically, I guess it's of the adaptation is that receptors can
27:39 adaptation. All right. And I describe this in the storytelling of when
27:44 used to first start um uh studying how neurons worked and stuff like
27:51 Um So adaptation simply is, is a receptor will become uh less sensitive
27:57 the presence of continued stimulation. the model system, they used to
28:04 neurons initially back in the sixties and the fifties were giant sea
28:09 All right. So, you they're about this big, they're easy
28:13 work with because they're very, very and docile. They got massive
28:18 So you can just kind of cut open and you can do stuff with
28:22 . All right. Both things about is they have I stocks, you
28:26 , an I stock is that thing sticks out and they have their little
28:30 on the top and that's how they their environment and they kinda look like
28:33 and one of the things that they do to test adaptation was they'd take
28:37 little tiny, um, uh, , which would have been like a
28:41 tiny stick and they'd have their little moving around and then they'd whack it
28:44 the eye stock. And what do think that slug did with its eye
28:49 ? Yeah. Just pulled it all . And then after a couple of
28:53 , what would that see slug Put it back out and then you
28:58 in and whack it again and you it right back in and it would
29:02 it out and it would whack it . And each time he did
29:04 it would be less effort trying to it. And eventually it just kind
29:09 said, oh, ok. this is my life now. And
29:12 it just kind of walked around or around and you just kept whacking it
29:16 the I stock and he just sat and said, yup. Ok.
29:18 is what's going on. All That's an example of adaptation,
29:23 Is when the stimulation no longer causes receptor to respond. Because the receptor
29:31 basically said, yeah, I'm constantly stimulated. So I'm going to reduce
29:36 response. And there's different ways that reduce response. We can reduce the
29:39 of receptors, we can reduce the of neurotransmitter, we release, there's
29:44 variety of different ways. But adaptation is simply that reduced response in
29:48 receptor. All right. So this occur at the level of cell.
29:53 can also occur at the level of central nervous system where the central nervous
29:58 says I keep getting signals from this over here. And I'm just going
30:02 ignore that for a while. All . In other words, I'm not
30:05 , I'm, I'm basically reducing the of receptors that I'm receiving or I
30:09 to receive the signals from you. that would be how that works.
30:18 right. So I kind of run a whole bunch of things really,
30:20 quickly here. Are there any questions any of the things I've mentioned so
30:24 ? Because we're now gonna kind of and kind of do a deeper dive
30:28 little bit in terms of intensity. right. Um If I came up
30:39 you and poked you, it would like, OK, you poke me
30:44 stop doing that. But if I up and smacked you in the
30:48 you know, same spot that I you, you would kind of notice
30:53 difference between the two right, same , right. The can of receptors
30:58 detecting me doing that. Your brain , oh I know the difference between
31:03 two things. You know the difference these two things, but it's the
31:07 receptor. How do we code this of information? You know the differences
31:13 magnitude? All right. This is uh describing up here, look a
31:21 potential. We talked about long time said look greater potentials have uh varying
31:28 . So varying strengths and they have durations and that magnitude and duration is
31:32 upon the magnitude and the duration of stimulus that is producing that graded
31:38 All right. So if I do little tiny poke, that's gonna result
31:42 a small graded potential which results in small release of neurotransmitter. But if
31:48 come and hit you really, really , that's gonna result in a lot
31:52 a very strong or powerful grad which release releases or results in a
31:57 of neurotransmitter being released. So you a big response to that, lots
32:02 neurotransmitter. All right. So this what this little thing is trying to
32:07 you is here. I am looking the receiving cell. So that would
32:11 the thing that's receiving the neurotransmitter. in this particular model, what am
32:15 doing? I got very little neurotransmitter on the cell. I have more
32:21 then I have the most so so good. And again, it's
32:25 same sort of thing, think of as on and off. So I'm
32:28 on the stimulation and it's lasting this and then I turn it off over
32:31 , I'm turning it on, but adding more and then I'm turning it
32:35 and then lastly even more. what's the result? Well, remember
32:40 here on what I'm doing is I'm the, what the potential is.
32:44 this is again, the greater potential from I'm, I'm measuring the
32:49 So here I get a very small . Here, I get a larger
32:55 . Here, I get the largest . All right. And what they're
32:59 is comparing it to thresholds. So what we're doing is we're measuring the
33:03 potentials further down the road. We measure action potentials there as well.
33:07 in the model, he's ju they're trying to show you like, what
33:10 you, what we expect would All right. Well, in this
33:14 , I got a lot, a EPSP or series of EP SPS and
33:19 wasn't enough to bring me up to . So I didn't get any action
33:22 . So I got no action That means I'm not re leasing any
33:26 of neurotransmitter. So does my brain the stimulus here? No second
33:34 stronger stimulus, stronger EP SPS. bring myself up to threshold. I
33:40 a series of action potentials. So boom, boom, boom,
33:42 boom, those action potentials once you an a potential are maintained, so
33:46 those keep going. So I release . Do I perceive the stimulus
33:52 Does the brain get the information? . All right now. So this
33:57 here would be me poking you. would be me coming up and barely
34:01 you. All right. And here's punching you in the arm,
34:05 Strong intensity, very strong epsp being in the receiving cell, the receptor
34:14 , which results in what? Relatively here we have. How many action
34:21 ? See if you can count How many do you have there?
34:26 ? See that's better. That's a answer. Lots. So what we're
34:30 here is that the strength of the results in an increase in the number
34:37 action potentials. Does it result in action potentials? Why all or
34:43 Thank you. So, an action is or it isn't. And what
34:50 showing here is that when I increase intensity. All I do is I
34:55 the number of action potentials. Remember talked about the uh refractory periods.
35:01 that. So in between here is refractory period. In a rest,
35:05 is actually a long rest in between . But as we get those things
35:09 and closer and closer, they're getting and closer so that they're almost pushing
35:12 against the refractory period, but not much that we're not still getting a
35:17 . So I get a big signal results in a lot of neurotransmitter being
35:23 . So my brain receiving that much neurotransmitter would say, oh, the
35:29 that was just received from this particular is a more powerful signal. Does
35:36 make sense? So the bigger the , the bigger the number or the
35:41 the number of action potentials being the more action potentials pre being produced
35:46 in a stronger signal to the central system. And it's in that code
35:53 more action potentials that the brain perceives stimulation? Ok. Does that make
36:02 ? Need at least one person on head? Ok. See when I
36:05 one, I got eight. That's . Yes, sir. Yeah.
36:10 when there is a bigger stimulation, , a bigger stimulus, my brain
36:16 that greater stimulus through the number of potentials that are being produced,
36:22 So it's the number of action not the, not the strength or
36:27 size of the action potential because they're the same size, right? That's
36:35 the only. Yes. Go I can say it one more
36:39 That's OK. Yeah, it's We all haven't had our caffeine
36:43 All right. The bigger the All right. So the bigger
36:51 the thing that the receptor is detecting larger the response and the larger response
36:57 through the number of action potentials right? Which results in more
37:03 So the brain perceives bigger stimulation or stimuli via the number of action
37:11 All right. So it's this right , the number of action potentials that
37:18 . All right. But you can think about it this way. All
37:24 . Well, no, I'm not go there yet. I'm not.
37:27 right. There's a limit though to number of potentials that a cell can
37:34 . All right. So the example gave you is poke versus punch,
37:40 ? So is there a large difference the Pope versus a punch?
37:46 If if not a big deal, can't even poke you hard. But
37:51 I punch you tell the difference, ? The other thing that happens is
37:58 as a signal becomes bigger and bigger bigger, it starts overlapping into other
38:05 fields and other sensory receptors start Ok. So it's not just the
38:13 of action potentials, it's also the of receptor cells that are being
38:17 All right. So how do we at this graph? We got 12341234
38:23 the four different cells in our little here. OK. So here's cell
38:28 one, it's being stimulated, it's more and more action potentials because the
38:32 is getting stronger and stronger. But at this point right here,
38:37 that's when number two gets recruited. so it starts producing action potentials and
38:42 keep producing more and more action And at this point, now I'm
38:47 in a third cell to produce action . So my brain is not only
38:53 more actions from one cell, it's getting a second cell and a third
38:58 and each of those cells are producing action potentials. And so instead of
39:01 just being one cell saying big it's two cells and three cells and
39:07 cells because there's a maximum number of potentials that a single cell can
39:14 So if I have a really big I'm gonna have in more cells and
39:17 going to produce as many action potentials as they're capable of producing in that
39:22 area. Does that kind of make ? All right, I can do
39:28 way just as a stupid example. want a stupid example? OK.
39:32 . All right. So I can quietly or I can talk loud,
39:38 ? But can I produce an incredibly sound by myself? No. So
39:45 if I recruited somebody else to make loud sound with me. So I
39:50 off low and then I get louder louder and louder. And as I'm
39:53 upward, one of you joins in makes the loud sound with me.
39:57 don't have to do it because I that's embarrassing. All right. And
40:00 as the two of us get louder louder and louder, the third voice
40:05 in and gets louder and louder and . And then the fourth voice until
40:08 all at the top of our lungs a louder sound than just one
40:14 Does that make sense? That's what is trying to describe. This is
40:18 recruitment is. It's basically saying that sort of signal as it grows,
40:23 not going to be just a single , it's gonna be multiple receptors that
40:27 gonna be recruited in because the stimulation going to be over into other
40:33 OK. And then our brain wants know some very specific information. And
40:42 is a really, really cool little or mechanism that cells use to magnify
40:50 amplify a signal without actually amplifying the . All right. So this is
40:55 you can think about it. All . So here you again, take
40:59 writing instrument that you have in your and just poke your skin and look
41:02 how it indents. All right. not like just at that single
41:06 you can actually see that there's a that's being formed, right? So
41:10 can kind of see it there. me see if I can draw it
41:13 this black, right? So if take a point and stick it into
41:19 skin, this is where it's t the skin is indented like.
41:23 right? So that would be the of the skin. So you can
41:27 I have a receptor here. I've a receptor in this location. I
41:30 a receptor in this location. This is getting the strongest stimulation,
41:34 Just like in recruitment. What we , this would be the, the
41:37 one. And then over here on sides, these are equal equidistance
41:41 So they're being equally stimulated but not strong as this one, right?
41:45 far. Are you with me? . So what's happening now is I
41:50 to perceive where that sensation is coming , from the in the brain.
41:56 getting a strong signal, I'm getting weak signals on the sides. And
42:01 the signal my brain would receive would pretty muddy. All right. It
42:06 be like taking your pointy instrument that holding in your hand instead of poking
42:11 like this. What you're doing now you're poking yourself at the flat end
42:15 your brain kind of goes OK? kind of that general area. All
42:19 . But that's not what the brain , it wants spec specificity. And
42:23 what happens is is that as that is moving downward. So here in
42:28 secondary neuron, we can see that have collaterals. Remember, collateral is
42:32 a branch of an axon and these are interacting with the nearby neurons that
42:40 downstream of the primaries. And what do is release a uh neurotransmitter that
42:47 an inhibitory neurotransmitter. And what we're is we're doing what is called presynaptic
42:52 . We talked about that we're inhibiting signal from being released from those outer
42:59 . So the only signal going forward the one where the stimulation is actually
43:03 place. In other words, in words, the big neuron or the
43:07 signal neuron is telling the other your information is not important enough to
43:11 up to the brain. So stop it and the surrounding weaker signals go
43:16 right, because they're ba basically being to be suppressed. And so now
43:22 brain only gets a signal from that neuron. And so instead of it
43:27 like this to the brain, it looks something like that, it's
43:34 . And so the brain goes, , that's where the stimulation is coming
43:40 . That's what lateral innovation is. inhibiting the neurons that are, are
43:45 located to the one that's actually being so that I perceive or receive a
43:51 that's much greater than it actually Now, this is done all over
43:56 place we're gonna see. Uh we won't see it all that much.
44:00 w um cause I'm, I'm gonna to keep it simple for you
44:02 But the eyes, for example, Have you ever done those optical illusions
44:07 it's like black and white? And can't tell the difference between the two
44:11 and white. They both look kind gray. No, just look up
44:15 illusions and you'll, that it's like of the first ones you'll ever
44:18 Basically, it's like a checker board they have like uh an object on
44:21 checkerboard and it's casting a shadow over black and white. And so it's
44:26 , is there a difference in the and the white? And you look
44:29 another course area because your brain is saying, I expect this pattern.
44:33 this pattern looks like this and they're the two blacks and the whites are
44:39 the same color, but your brain perceiving. Otherwise it's functional this right
44:45 , lateral inhibition. All right. the purpose is to increase contrast to
44:52 your brain know where stimulus stimulation is place. All right. So what
45:00 just covered here are some generic or mechanisms. First off, we said
45:06 , a bunch of different ways that can classify receptors. So that's a
45:10 way to kind of do this versus , right? Then the second thing
45:15 did was how do these receptors What do they, what are these
45:18 potentials? And how do they send signals forward? What is this
45:23 versus tonic? Stuff. All And now what we're doing is we're
45:26 walk through some basic receptors. All . So we're gonna talk about the
45:31 ones. These are the easiest we've seen these when we talked about the
45:35 . Did we talk about these Yes, we did. Are we
45:39 back and having to be tested on again? Yes, we are.
45:42 . Sorry. I know. But gonna keep this simple. All
45:47 So first off tactile receptors, why talk about them? The most numerous
45:50 , they're uh fairly well classified. are all mechanical receptors. All
45:57 we're talking about changing the shape of receptor. They're located specifically in the
46:02 and the sub Q layers. All , they can be either simple or
46:07 can be complex. So again, is using that language of encapsulated versus
46:12 encapsulated. So when we look at sensation, what are we talking
46:17 We're talking about touch, pressure and . All right, touch simply provides
46:22 about where, where that uh stimulus occurring. What is the texture,
46:26 size shape and or movement of that . So those are all the things
46:30 we're trying to determine in that sense touch. What is pressure?
46:36 pressure is give you a sense of how much or how strong or
46:41 big something is. So the the deeper it goes, the more
46:45 it's producing. And so that's an of like size and, and uh
46:50 and then finally vibrations, these are rapid, repetitive sensory signals. This
46:55 primarily with a sense of, of grip, how you're holding stuff
47:00 you can do this across the run your fingers across the table like
47:03 . You can feel the fingers right. You, you lack grip
47:07 that's happening, right? And what doing is you're getting fluttering vibrations that
47:12 not very, very deep when that's . All right. So the first
47:19 are the un encapsulated. All So here we have dendritic ends that
47:24 a protective coat, which means that encapsulated must have some sort of protective
47:29 around them. There are three basic . These are the free nerve
47:32 which you'll see up here, the hair plexus, which we talked
47:35 which is basically a free nerve ending well, but it's just wrapped around
47:38 hair. And then we have the disc, um which is this structure
47:42 here. The merkel cell is the . That's the, it's actually located
47:48 the epidermis, but the sensory neuron which it is attached or affiliated is
47:53 within the dermis itself. So, they've located primarily met thelium primary connective
48:01 , these are unmyelinated if you're what type of signals are you sending
48:05 or slow, slow? So, these really, really important signals?
48:10 particularly? Ok. So the free ending in the hair plexus or root
48:16 plexus least complex. They're what we slow adapting. So, these would
48:22 phasic receptors. Ok. They project to the CNS uh through a variety
48:30 different types of fibers which we're gonna about later. Um close to the
48:36 uh polymodal. All right. polymodal means they can detect some,
48:41 temperatures, some detect, touch, detect pressure. So they are capable
48:45 detecting all sorts of different things. right, that's why you're able to
48:51 or kind of understand. I'm being by X the Merkel cell. On
48:57 other hand, is a tonic OK. So the Merkel cell remembers
49:03 up in the epidermis, it's in uh stratum Bisoli uh the neuron to
49:08 it's associated is inside the dermis. These you're gonna find in the tips
49:12 your fingers and also in the Why do we want a lot of
49:16 in the lips? We already talked this. Why you wanna watch what
49:21 putting in your mouth, right? it hurts the lips, it's gonna
49:24 things internally. All right. So what we're doing is we're texturing textures
49:30 the shapes of objects. All then we get down to these
49:38 All right. Now, the I think I've already shown you how
49:42 can separate them out, right? of them are found in Globus
49:47 So that's basically all the skin in body like on the surface. And
49:50 one is found in mucous membranes. so you just swap one out
49:54 All right. So um the Meisner ruins and the Pinion, those are
50:01 in Globus skin Krauss uh replaces pinion mucous membranes. All right, almost
50:09 of these again, are Mecano And so here we can kind of
50:13 a little bit uh more closely at . So the dendrites are wrapped up
50:17 these uh lamella, lamella just are to layers. And so what you
50:22 is the dendrites go back and forth so, and what this does is
50:26 says, hey, um I'm I'm the connective tissue to increase the surface
50:33 so that I can get a signal any direction to activate this particular
50:38 All right, these are phasic, right, the things that they detect
50:44 their nearest surface is light, touch light vibrations. Again, fingertips,
50:54 ruin, these are deeper down. what you have is you have um
50:59 uh piece of collagen uh which gets around by the dendrites and then you
51:05 that up in connective tissue. And now what you do is if you're
51:08 to twist or manipulate that connective tissue the outside, that means you're manipulating
51:13 collagen on the inside, which is detected by those dendrites. So,
51:18 you're doing is you're detecting the change shape. All right. So this
51:23 us grab things, this helps us hold things. So we can actually
51:27 , am I actually touching? Am , am I going deep? So
51:30 is about midway in through, through the epidermis. These are
51:34 they do not exhibit any sort of adaptation. Krauss is the weird
51:41 . I said this is the one found in the mucous membranes. Um
51:45 usually deeper. So I don't know I have light pressure here, but
51:49 just go with what it says up And then temperature is another thing that
51:53 actually detects. All right. But key thing here is mucus uh
52:01 Um oh And let me just show so you can see here the
52:04 And so it's there's that capsule and uh pinion is basically you have the
52:09 and you just wrap it in successive of connective tissue which amplifies the receptive
52:15 . This is in the uh hairless or glo skin. Um So,
52:21 , rapidly adapting versus uh this one versus the tonic. So this is
52:27 , much deeper. What we're dealing here is deep pressure and deep
52:32 All right. So it's going it penetrates down deep. Um So
52:42 this point, I think all I'm in is just understanding is it fast
52:46 where it's located? What is it of what if it detects? But
52:50 it, you know, if you think about it is deep, it's
52:52 pressure. If it's up near the , it's light pressure. All
52:57 Thermo receptors. These are cool. here likes mint, like York peppermint
53:03 , I mean. Yeah. You get that cool sensation when you
53:07 York peppermint Pattie. Ok. And we talked about hot food,
53:10 food. Yeah. Ok. these are thermoreceptor that are capable of
53:19 temperatures and the reason I mentioned those is because they also detect specific
53:26 All right, that's what this is to show you here. You don't
53:29 to know which one to do, that's, this is just a picture
53:32 it's interesting. All right. So thing that's interesting or most interesting is
53:37 we have more cold receptors than we warm receptor or heat receptors. And
53:41 so that, you know, um is the a is not the absence
53:45 heat. It's just a very, low level of heat because you just
53:50 it's a scale. And for we just, we find a level
53:53 comfort that's between say 100 degrees and 70 degrees. And that's Fahrenheit,
53:59 Celsius because 100 °C would suck. , anyway, the thing is they
54:06 detect temperatures below like 10 degrees. , really what they're doing is they're
54:10 for those extremes, those things that dangerous to us, right? So
54:15 about like if you have you ever dry ice? Yeah. Yeah.
54:20 . Ok. Dry when it touches skin, it feels like burning,
54:27 ? Cold feels like burning, So you kind of get the sense
54:32 . What is it doing? These are not like going oh, it's
54:37 , you know, it's like, this is causing damage to cells and
54:41 what the signal is. Um The of receptor is called a TRP receptor
54:46 not so important, but you can there is TPTRPATR pm so on and
54:50 forth. Those are the different different families. Um So again,
54:56 just trying to show too here. I mentioned mint. So mint activates
55:00 one receptor. So there's a chemical mint menthol that is detected. Um
55:07 you like spicy food, we're looking TR PV. So those chilies,
55:11 I don't know why they spelled it . That's not how you spell
55:14 That's that right there is what we in Texas without beans. Uh You
55:20 , chili is spelled with an So when we're talking about the ghost
55:24 , jalapenos, you know, green , we're talking about the molecule within
55:29 structure which is cap cape capsaicin. . Um And that's what gives you
55:35 sensation of heat. And the thing is if you don't have the
55:40 you don't detect it. So, right, I'm gonna, I'm gonna
55:45 cruel for a moment. If you take a, a jalapeno, you
55:49 , a little jalapeno slice and feed to one of those cute little squirrels
55:52 there. God, yeah, that's what will happen is it will freak
55:59 and it will not beg food from for quite some time. Ok.
56:04 reason for that is that capsaicin receptors located in mammals. We have uh
56:11 have these receptors. I know you . Oh, it's so funny.
56:16 mammals have it. If you have bird feeder, you can buy bird
56:20 that has cayenne pepper mix in. that the squirrels don't eat the bird
56:24 because you don't want the squirrels ring bird seed, right? Birds don't
56:29 that receptor. They can eat this all day long. In fact,
56:32 how chili peppers get their seeds Is the birds eat the little tiny
56:37 back when it wasn't like the varieties we have and then they fly
56:40 they poop out the seed and then seed gets planted because it has the
56:44 around it. And that's when you a new pepper plant. Ok.
56:49 it's a strategy to keep mammals like from eating their food. They are
56:54 their food, but the, the fruits of the chili plant, that's
56:58 , that's the chemical. All But again, these are receptors that
57:05 shape in response to changes in And so they're tuned to a specific
57:13 . They just also happen to bind a chemical that allows you to perceive
57:18 , that sensation. Why mint feels because it's at the coolant, why
57:23 feel hot because they're tuned to that range. No C acceptors, lots
57:34 different types. So we're talking about receptors here. So typically they're gonna
57:41 concentrated in areas that are more prone injury. So let's think of areas
57:45 were prone to injure a lot, , toes, bottoms of your
57:52 hands, right, face, All right. So these adapt very
58:02 . So if they adapt slowly, means they are tonic, right?
58:07 they're gonna respond to all sorts of . So, cellular damage, noxious
58:13 , cellular signals. So there's things cells, when they start perceiving
58:18 we will send out signals to amplify response. So these are examples of
58:24 . Again, you don't need to these, there's different types of
58:31 And so I've already told you pain a protective mechanism. So let's say
58:36 running along on our wonderfully flat Hu sidewalks and you twist your ankle.
58:42 know, what do you do? is your body telling you when you
58:45 that pain? Stop, quit doing ? All right. Don't keep doing
58:52 or you're gonna continue to damage the . That's the idea of what pain
58:56 . All right. Fast pain, pain is simply, it's felt
59:00 very quickly, it's very sharp, could be localized. So if you
59:04 poked by a needle, that would an example of sharp pain or fast
59:07 , slow pain, these are the uh dull or unpleasant ones. It's
59:12 . It's not easy to locate. like when you have that pain in
59:16 gut and you're like, oh I just don't feel it hurts this
59:21 . All right. That would be slow pain. All right. So
59:23 increase of over time acute is said versus chronic, which is persistent and
59:29 visceral pain is simply one that originates the gut. So it's abdominal typically
59:35 poorly localized because visceral receptors are just of like, well, someplace around
59:44 referred pain. If you have a attack, what do you grab?
59:51 arm, left arm, you see doing this, you know, grabbing
59:57 , they may be having an especially if it's an older person like
60:03 . Ok, you had appendicitis. had the joy of appendicitis besides
60:11 No. How far we have one ? All right, I saw
60:15 you don't, you don't have to it. You, you just
60:17 hide down, hunker down. All . Appendicitis sucks a lot. All
60:22 . I was up at summer camp appendicitis. All right. It was
60:27 . It started off as a stomachache it just amplified and stayed there and
60:31 was just indistinct again. That was abdominal pain. And then they finally
60:36 after three or four days that maybe wasn't gonna go away and it was
60:39 something worse. And so they took to the hospital, the er,
60:42 the physician comes in. First thing does is presses right here. Presents
60:46 here and it's just like I shot and like, ok, we're gonna
60:49 to take that bad boy out. I was lucky because mine ruptured about
60:53 hour before they took it out. they got to keep me open
60:57 like, four days. Yeah. , that's not a good thing.
61:01 is gross. Yeah. You irrigate wound. I had to pack the
61:05 myself and, you know how, how I got an interest in
61:10 It's like, you know, stuff that. So what referred pain
61:15 is simply the perception of a visceral that is being perceived on the surface
61:22 the body. All right. And I describe one that's the most
61:26 which is the heart attack. Like said, it's gonna be the left
61:29 you can see here it's being shown kind of how it is, but
61:34 can see other things. It's like , we use these as as instruments
61:37 as tools in in the medical field kind of identify where areas might be
61:43 damaged or having some sort of And so you can kind of see
61:48 here's the appendix, right? The sits there, but the pain isn't
61:53 deep in the abdomen, it's on surface. I mean, you are
61:56 sensitive to that sense of touch on surface. All right. It's a
62:02 sense of origin. And again, can just kind of pick stuff.
62:06 is a fun one liver and gallbladder here in the neck. What?
62:10 , I know it's liver is over , gallbladders underneath it. So why
62:15 , that's just where perce uh All right. But the reason we
62:20 this happens is because of a shared tract. And so what this means
62:26 is that you can imagine there are coming from those organ or organs and
62:30 traveling alongside other, back into the nervous system. And because they're using
62:35 same tract as these other sensory the that information is sent in
62:41 into a special location. It goes the same place into the thalamus and
62:45 sensory cortex. So the brain perceives pain occurring in this location even though
62:51 not there, that's probably why it's . We don't really know. But
62:55 what the this idea is. So . Pain is simply a perception of
63:04 . That is a false origin that's for medical um diagnosis. Now,
63:10 pain pathway, this is our first to a path. All right.
63:14 I'm gonna, I'm gonna put a caution up here at the front end
63:17 very often these pathways have these horrible to them and they are like these
63:21 $10 word names and, and really the, all the name is is
63:26 where it starts and where it OK. Now this one doesn't have
63:29 , this is just I'm calling it pain pathway. Oop, I just
63:33 . Just give me a sec that of year to change the battery
63:46 Mhm And so when you look at pathways, the first thing I'd say
63:57 one, don't panic when you see name because it's just telling you
63:59 the two and the from or the and the two. And then the
64:03 thing is that typically there'll be three two neurons in the pathway. So
64:07 looking at this one, how many are in the pathway? Three,
64:12 ? It's first order, second And then finally, here's your third
64:17 going up there. So you just , here's the first, there's a
64:21 and then the third is that All right. So typically they're gonna
64:25 three, but in some cases, see two and again, we'll point
64:29 which one's which. All right. in this particular case, we're looking
64:32 three. All right. And so you just do is you just ask
64:35 question, right? First order neuron always the one that starts the
64:39 Second one's in the middle and third is where it's finally ending up.
64:42 right. So here the first order , what we're gonna do is we're
64:45 take the information from wherever the receptor . So either that cell itself is
64:50 receptor or it has a receptor cell associated with it. So the thing
64:56 we just described a couple of slides . So in this case, we're
65:00 at a tack, we're going to uh the uh Sleeping Beauty with that
65:04 . We're gonna sit there and put finger on it. You guys saw
65:09 Beauty, right? OK. Touch spindle. OK. Same sort of
65:14 . Don't touch the sharp thing. to sleep forever. All right,
65:19 gos up, goes up through the order neuron. Notice where the cell
65:23 is located, dorsal root ganglia goes the gray matter. You can see
65:28 here is an inter neuron because really you'd expect is also you'd expect one
65:32 back out to tell that you to your finger up. So that would
65:35 the reflex. But notice whenever there's reflex, I also have a perception
65:39 the pain too, right? That's we're dealing with is the perception
65:43 So here, what we do is terminate on the second order neuron.
65:47 second order neuron crosses in this that's called a degustation and then it
65:53 up through a specific pathway. This gonna be the spino thalamic track.
66:01 come back to that later. But I said $5 words, $10
66:04 spinothalamic track without knowing anything else. does it start spine? Where does
66:10 end up thalamus, spinal thalamic This is how difficult this track stuff
66:15 . All right. So spinal thalamic . So here we are in the
66:19 and now here the thalamus takes that and it's gonna send it to different
66:24 . Now, in our little cartoon , the third order neuron that they're
66:26 going up to the Savanah century Somatosensory cortex is responsible for telling you
66:33 something is happening, right? Remember map that Monus we looked at.
66:37 it's basically saying, oh, you're touched on the finger. So I
66:40 know where that sensation is occurring All right. What about the insular
66:47 ? All right. Well, that's place that this particular pathway is going
66:51 . Do you remember insular cortex if looking at, I don't know what
66:53 words mean. Did we learn about structure called the insular? So we're
66:59 talking about the cortex of that And here this is where we're distinguishing
67:04 particular stimulus from one other type of and the other types of stimulus that
67:08 might be getting. So, in case, it's an itch versus pain
67:12 nausea versus. So in this what would we be perceiving pain?
67:16 so the insula says, ah that's that you're perceiving, send it up
67:23 the anterior cingulate cortex again, that looking at those words going what
67:27 All right, remember when we talked the limbic system and we talked about
67:30 singular Gyrus. This is where we . We're in that cingulate gyrus.
67:35 here we're talking about what do we with this pain? If I poke
67:40 finger, what do I wanna do that? I mean, I'm gonna
67:44 my finger. That'd be a But what am I gonna do
67:51 Maybe curse a little bit, maybe angry. I'm not gonna be happy
67:56 it. Right. So this is we're talking about when the information is
68:00 distributed by the thalamus, it sends to different areas so that you process
68:05 and you decide what needs to be with it. All right. So
68:09 this particular case, probably pain, , maybe a little bit of cursing
68:14 sort of thing. Now, relative to the sense of touch.
68:20 you think it's more important to know pain is occurring than just being
68:24 Ok. So we're gonna use we're gonna speed things up. And
68:29 again, here's a chart. You need to know the chart. You
68:31 see that there's different nerve types. listed three out here and I'm using
68:35 three to kind of give you a generic sense of what's going
68:39 So we have really, really fast slower. All right. So notice
68:44 are both myelinated. So all the are myelinated, so they're particularly
68:50 but alphas are thick, these are , so thick versus thin, the
68:55 the fiber, the faster the so thick myelinated are always faster.
68:59 I throw a baseball at your it hits you in the head.
69:02 do you feel a sharp pain? ? That would be an a alpha
69:09 OK. That would be an example that. Sure, localized pain.
69:14 right. Alpha delta, these are diffuse, these will be like the
69:18 pains. All right. So in particular case, alpha deltas or a
69:24 would be the pain that you perceive you've been hit with the baseball.
69:30 right, sharp pain. And then do you have is that throb
69:35 won, won, won as the D or A Deltas. C fibers
69:41 a different type. They're much, slower. C they're thin, they're
69:45 . And so these will be detecting types of stimuli. And so this
69:49 like mechanical damage, chemical damage, and cold stimuli. So this would
69:53 like what you'd see in a All right, this is the stuff
69:57 the leftovers, right? So if have inflammation, oh, I've got
70:03 perception of heat, right? That be ac fiber doing that. We've
70:12 done this, haven't we? Nothing more joyful than stepping on a
70:19 lego. Have you never done Just counted them on your blessings?
70:25 right. I spilled on myself Pain fibers themselves are gonna be producing
70:40 signals and inhibitory signals. They're gonna things to do stuff and they're gonna
70:46 things not to do stuff. So you're talking about the things moving up
70:50 spinal fibers, those are gonna be . So let me go back.
70:54 these things coming up, there's gonna fibers coming down that are gonna modulate
71:00 and determine whether or not a signal to move forward or, or
71:05 So again, think about eating spicy . When the first time you ate
71:10 food, it was hot and you're , uh uh I ain't doing that
71:14 , but then something happened, you of felt good. You notice
71:22 So you're like, no, I like the spicy food. All
71:25 the people who eat spicy food, eat it because it brings us
71:29 A sense of well being. All . And the reason for that is
71:35 our bodies don't like pain. as we said, is a signal
71:42 say, stop it. But what happen is if we stopped every time
71:46 occurred, then we never move ever . And so our body sends signals
71:51 reduce the pain to give us a of mm basically to serve as a
71:59 or an anesthetic to that pain. these terms have a specific meaning and
72:04 modifies a perception of pain. That not mean the receptor doesn't work.
72:08 means the receptor is trying to send signal. But what you're doing is
72:12 saying, yeah, you know what don't release the neurotransmitter. All
72:16 That would be an example. So not perceiving it. The information doesn't
72:20 up at the brain. All Well, what about an anesthetic?
72:24 , here what we're doing is we're the generation of the action potentials.
72:28 an analgesic while like this is like aspirin is basically saying, yeah,
72:32 pains, uh the cells are still . They're still trying to send
72:36 I'm preventing the signal from going forward with the anesthetic. We are basically
72:41 the cell is not able to produce nonresponding. OK. And then the
72:50 part is, well, you, produce pain. So I wanna
72:54 I want to respond. I want make life a little bit better.
72:57 I'm gonna produce opiates. We call endogenous opiates because they're made inside our
73:03 . But there are also exogenous opiates naturally occurring opiates. So an endogenous
73:10 would be like an endorsement, You got who here likes to
73:15 I mean, just likes it like can't wait to get up in the
73:18 and do it, right? Why? Uh I mean, I'm
73:24 saying that like, why is it , are you crazy? Although part
73:27 my brain is, but part of is like you get what is called
73:32 runner's high? What is the runner's ? It's basically your body experiencing the
73:40 . And then it says, I don't want to care about this
73:45 anymore. I want it to go . So you release the endorphins and
73:49 like I can keep going. This why we eat the spicy food because
73:56 time I put that ghost pepper in mouth, oh, that's hot.
74:00 then my brain goes. Uh, , don't worry about that. I
74:02 your back. The endorphin. All . So there's a whole bunch of
74:08 types of opiates. The endorphins are most obvious ones, but they have
74:11 cephalon, the dynorphin. Just whenever say one, you'll get all three
74:15 them, you know. But the here is I am presynaptic inhibiting.
74:21 it's just like that lateral inhibition. not letting that cell release its
74:26 So the cell is still responding and , oh, bad things are
74:29 But what I'm doing is I'm blocking signal. I'm inhibiting the signal from
74:33 forward. And that basically says, , not gonna happen. There are
74:40 ones that you can do. These the exogenous ones. So morphine,
74:44 the chemicals they give you, uh you know, to stop pain.
74:49 would be uh I mean, anything comes from Poppy, tho those are
74:53 opiates. Those are the ones. right guys. Well, it is
74:58 . Obviously, you guys are running of here. If you want to
75:01 talk to me, I am but please read that email first.
75:06 welcome.
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