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BIOL 2301 Human Anatomy & Physiology I - BIOL2301_lecture06_0613
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00:00 Um, and I'll actually record this just so that everyone knows.
00:05 um, we have one person needs take the test today because unfortunately when
00:10 took the test, there was a alarm in the middle of the
00:12 And so is that you? Ok. Um, and so
00:17 you know, close the center you know, have to retake the
00:21 . So, um, so we talk about the test until tomorrow and
00:25 I say talk about the test, , I may not even bring it
00:27 class. I may just post like curve and what grades mean and everything
00:31 that. Um, you guys, got a couple of emails,
00:34 about, I can't see my I, you know, I can't
00:37 this, that and the other look now canvas is one of those things
00:41 it's a moving target for us. right, your grades are safe.
00:44 , they're there where you wanna So if you, if you're wondering
00:46 your top a grades are, go top hat. Um, I spent
00:50 of the day yesterday, emailing back forth very slowly. It was like
00:54 motion. Emailing, whereas like they email me and I'd respond and then
00:58 three hours later they would respond So with their customer service trying to
01:02 out why is it not syncing? they're like, trying to put it
01:05 me. And I'm like, it could be me, but I
01:08 all your suggestions and it still doesn't . So I think it's your
01:13 Um, but anyway, so if looking at trying to figure out
01:16 you can pull top hat off of hat and kind of figure out where
01:20 are. It's real simple. Look your percentile score if you're like scoring
01:24 the 90th percentile better, just that's points right towards your final grade.
01:27 real simple to do it that Um, because it's just 10% of
01:31 grade. Um your test, if wanna see your test score and
01:35 you haven't been able to find Go to that Casa button, click
01:38 Casa button and there's something that it you to see the score right.
01:42 Later today you can go there and at your exam, right? I
01:47 to release it first. It's set like a seven day timer, but
01:50 can speed it up apparently. So gonna try the thing they told me
01:54 work. We'll see. All So I'll let you know when I
01:57 that, I'll just email you guys you go and look at your
02:00 Um So we have an extra credit and that should become available uh later
02:07 . I think. All right, of the extra credit, you
02:09 you could go and do it without at your exam. But the point
02:12 it is to look at your figure out why you didn't grade,
02:15 the grade you wanted or to figure why you got the grade you
02:18 right? You know, and then , oh, ok. I can
02:21 why I miss these types of All right. So I'm gonna make
02:26 to how I prepare myself on the . So I don't miss questions the
02:30 way in the future. All that's the whole point of going through
02:34 extra credit exercise. So the first credit was, see, were you
02:37 for the exam? Did you do the things you thought you were necessary
02:40 get the grade you wanted? And now you know what grade you
02:43 Now you go back and reassess did strategy work and that's all it's doing
02:48 it should take you like what, minutes? How, what was the
02:50 extra credit? Like two minutes? . So it's kind of the same
02:53 . That's three points. So um till the exam opens and then do
02:57 . But if you have to get point, you know, points are
03:00 most important thing about this class for , then go do it right.
03:03 would recommend that it's not the most thing that you're doing in this
03:07 I would say this stuff that we're here is all right. Um,
03:12 see. What else is there anything I wanna talk about? Uh,
03:15 remember we have a three day weekend week. Uh Monday is Emancipation
03:19 The university is closed. Your exam on Tuesday. Ok. If,
03:24 some reason I don't think anyone signed for exam two yet. It's,
03:28 available. You can actually sign up . Yeah, just don't do
03:32 This, I guess you could do this second if you have to.
03:36 , but do not sign up for 19th because the university is closed,
03:40 closed. Everything is closed. If a date for the 19th, don't
03:44 that. June 20th is the day we're doing our exam, right?
03:48 if you sign up for the it only shows you the 20th.
03:54 . No, no, no, closed. Yeah. You, you
03:57 here, I'm not gonna be I'm gonna be sleeping in. I
04:00 you all to sleep in as well then I expect you to go out
04:03 Party Emancipation Day. All right. right. Uh What we're doing is
04:10 feel really, really thick in terms the amount of material that we're covering
04:15 it's like five chapters of material. really isn't that much. It,
04:22 feels like it because it's just so every day. We're gonna basically be
04:26 something else. But some of the that we're covering in this unit is
04:29 of the easiest stuff and that's not make you think. Oh,
04:31 I don't wanna have to do Like learning joints are, are
04:35 It's just, we name them and see how they move and that's pretty
04:38 stuff. Ok. So, while seems like there is a lot of
04:43 here, it's more like a bulk than a difficulty thing. All
04:49 And what we're gonna do today is going to talk about the skin.
04:53 , I'm gonna approach this very differently just so that you can see
04:57 All right. So at the beginning every class, what I'm trying to
05:00 is I'm trying to tell you what gonna cover. All right. So
05:02 gives you a sense of what is ? I'm trying to learn,
05:05 And remember what I said at the of every class, what are you
05:07 to do to yourself? What are supposed to ask? What did I
05:11 today? What was it? I supposed to learn? And that should
05:14 your, that should be an approach you do a after every class,
05:17 just my class, every class you . If you're in CALC today,
05:20 learned how to do this type of , right? And it helps you
05:25 kind of keep focused on what's gonna on the exam because there's nothing I'm
05:28 ask you on the exam that we cover. All right, I'm not
05:32 there trying to go through the book figure out what's the most difficult thing
05:35 find. I'm literally asking you these the things you learned. Did you
05:40 them? All right. So what are we learning about? We're
05:44 about the skin and its derivatives. actually up here on the slide right
05:49 . Like I said, we're gonna a little bit different. The other
05:51 we're gonna do because it's a summer . We're gonna do a little bit
05:53 bones at the very beginning or at end of class, right? So
05:57 little bit of understanding how bones So we have kind of a big
06:01 which is gonna be the integument and there's a little bit of things over
06:04 on the end, the intent is skin and its derivative. So what
06:08 , what is skin and what is derivative? Well, skin, you
06:10 , that's the stuff. The derivatives hair and nails, you like fingernails
06:17 toenails and uh the glands like your glands. All right. So at
06:24 end of this class, you're gonna out of here knowing in theory what
06:28 skin is, structure and function, the hair is, structure and
06:34 what nails are structure and function, the glands are, structure and
06:43 And then we're going to get to bones and the bones is going to
06:45 more like, what's the definition of bone, that sort of thing?
06:48 right. So with that in everything that you needed to learn is
06:53 be based on that, right? if you had to go home today
06:56 explain to mom, dad, the , the girlfriend, the dog,
07:00 it is that you talk to, you get home, the roommate,
07:03 would be able to explain in theory it is that we just learned.
07:08 so our starting point is here, is the skin? Skin has two
07:12 regions? When I was in grade , we had a little joke.
07:16 , your epidermis is showing and people look down, you know, like
07:21 the epidermis? It's the outer layer the skin, right? And everyone
07:26 and kindergarten was great and fun. then, you know, we'd get
07:29 juice boxes. Actually, they didn't us juice boxes. There were no
07:33 boxes back in the day. All , we drink sugar straight from the
07:37 bottle. All right. So we the epidermis and in our cartoon up
07:43 , the epidermis is the pink right? And you can see what
07:46 it do. It comes down and , right? So that's the epidermis
07:50 then underlying that is the dermis. skin exists really in two major
07:57 Now, some textbooks are gonna point a third region, right? And
08:02 this thing down here, which is to as the subcutaneous layer or the
08:07 . And again, you can look the terminology epi above dermis would be
08:11 the center area. The thing that's of focused on and the thing underneath
08:14 dermis is the hypodermis. So, , and hypo are those prefixes that
08:18 use. The epidermis is a vascular its job is to serve as a
08:24 layer. So, what do you it's made up of? Carrot is
08:29 be in there? Yes. But type of cells it starts? The
08:34 ? Say it again. Epithelio, cells. Yeah. And then the
08:39 itself has all the vasculature, all nerves you can see here, the
08:42 penetrate down into it. And so consisting primarily of connective tissue. All
08:50 . And there's some smooth muscle that be associated with it. So you
08:53 see here is a, a little showing some of the smooth muscle.
08:57 and then under lying that that's where gonna see that hypodermis. If they're
09:02 , if, if we define it's basically this is where you're gonna
09:05 the adipose tissue. Um It's not part of the skin, but it's
09:10 part of the underlying stuff as It kind of sits as a layer
09:13 connective tissue that's separate from it, it's just easier to include it.
09:17 right. And what we're doing is is what anchors the skin sorry,
09:22 , if this is the skin, is what anchors the skin to the
09:26 structures. Now, I use this an example and it's not a best
09:31 because not everyone in here hunts. anyone here hunt? It's OK to
09:36 that you hunt. No. All . Have you ever had to skin
09:40 like if you buy skin chicken and don't want that nasty skin on the
09:45 , what do you do? You of go in there and take it
09:47 and then underlying the skin as you're off that stuff, there's this layer
09:52 connective tissue holding the skin on. the hypodermis. All right. And
09:57 with all the fat in there and it serves as a great layer of
10:02 . It serves as a great shock . Like I said, when I
10:06 young, I got pows, we call them pow, pow. We
10:09 them swats or get your butt in because I know you're the one who
10:12 this, you know, and you right on the butt, right?
10:17 why do we do the butt? we have a lot of fat there
10:22 it's easy to take swats there. right. So what is the function
10:33 these things? Well, the epidermis multiple functions. We just like to
10:38 of it as a barrier. It's protective barrier. And so in terms
10:41 the barrier, you can see there's , physical, biological temperature, even
10:46 . All right. We don't think U V light as being radiation,
10:49 anything on that light spectrum on the spectrum is radiation. Right. We
10:56 the word radiation. We think bad . But it's basically, it's energy
10:59 being propelled and that's what that spectrum . So, radiation is absorbed in
11:05 layer. Some radiation. Right. prevents us from losing water.
11:11 we're a water resistant organism. Water go in water doesn't come out through
11:14 skin. We basically have this waxy . We're not like a duck,
11:18 we do that as well. A of people don't realize this, but
11:21 a lot of metabolic activity taking place the skin. I tell this story
11:26 every class because I like to point how stupid people can be sometimes.
11:30 , it's not really stupid. I to work in a lab long before
11:34 got into graduate school and it was summer thing. So, like right
11:38 when it's nice and hot, it summer. This is when I'd work
11:41 a lab. And um I would these experiments where it's like you'd set
11:47 up and then you'd go away for little while. And I, this
11:50 at, so this is in El and our building was like six stories
11:54 and there was actually two buildings and have like this breezeway that kind of
11:58 through them, you know, like between the two buildings. And at
12:00 top was kind of this outdoor sitting on top of the two breezeways.
12:05 between the labs that I was working the experiments, I'd go and hang
12:08 up there and what I do, just sit out there and, you
12:11 , catch some rays, man. there was a guy that worked in
12:13 lab and he was not a very person and he was like a puppy
12:17 . He wanted to learn everything. so I'd go and do my experiments
12:19 I'd say, hey, man, gonna go and I'm gonna go uh
12:22 some vitamin D and he was I wanna come watch and I'd be
12:29 , OK, come on. So went upstairs and I sat out there
12:32 I sitting there just kind of kicking , just enjoying the sun. And
12:35 like, when are we gonna go the vitamin D, dude, we're
12:38 it right now because that's what the does. It absorbs U V
12:43 We'll talk about this in a second it converts it into vitamin D.
12:45 takes cholesterol that you've made and converts into vitamin D. So skin is
12:50 just a protective barrier. It has activity that's important for your survival.
12:56 that fact that we sit inside all time and stay on our phones actually
13:00 counterproductive to our body's function. We sunlight, right? Um There's some
13:09 minor metabolic stuff that we're not going talk about uh it secretes uh metabolic
13:13 . Um And it's also selectively We talked about lotion going into the
13:17 . That's meaning if you're fat you can penetrate through the skin.
13:22 Many, many parts of the immune are found in the skin. You
13:26 secrete all sorts of fun little things kill microorganisms through the skin and then
13:32 you get to the dermis. So that outer layer, that protective
13:36 the, the the layer that isn't protection. If you go down in
13:40 dermis, this is where we're gonna temperature regulation. So this is where
13:44 blood vessels are. So your sweat are found there. So this is
13:48 when our body temperature rises, what gonna do is we're gonna vasodilate,
13:52 that hot water up near the surface then we're going to secrete fluids onto
13:58 surface. And then that heat is from the, the, the water
14:02 the blood to the water on the of our bodies and it evaporates and
14:05 it goes. And that's how you yourself down. All right, we
14:10 have adipose tissue there. That would the hypodermis that we're saying it kind
14:15 counts, but it doesn't. And this is where all the sensory receptors
14:19 located in the body on the surface your body. So it has a
14:24 in uh detecting touch or pressure or pain. That's also no c
14:29 Um, no. Uh, if see this word, it looks like
14:33 don't know what it is. No is, has the same root as
14:37 . So, think of something that noxious and irritating. That's pain.
14:41 right. No. All right. also thermoreceptor. So that's when,
14:46 know, when I touch a hot to move my hand away type of
14:49 . All right. So we got and we have these two structures.
14:55 what we're gonna do now is we're dive deeper, that's enough to get
14:58 through the first. Probably. right? But obviously, that's not
15:03 that's there. If you're dealing with , that means there are cells that
15:06 there. So which cells are part the epidermis? And there's two major
15:11 . The first group are called the sites. They're the ones that are
15:14 . These are the most abundant So, in this picture, when
15:17 looking at, at the epidermis, that's above that line, which is
15:22 is basically Carroo site except for a of them. All right, the
15:27 sites produce carrot, that's where they their name from. And so they're
15:31 ones that give or create that toughness these cells. All right. And
15:35 all gonna be connected to each other those desmosome. You're sitting there
15:39 well, why do I have to all these stupid names for all these
15:41 types of connections? Because we're gonna them all over the place. So
15:46 desmosome make these tight junctions and these these tight attachments. And so this
15:51 what gives the strength to the Now embedded in between the carno sites
15:59 and there are going to be the melanocytes penetrate in between the
16:05 They have these little tiny spindly arms kind of push in between the
16:10 And what the melanocytes do is they a pigment called melanin in response to
16:14 presence of UV light. Right? different types of melanin, which we'll
16:19 about in a moment. But when get exposed to melanin that uh when
16:24 get exposed to U V light, U V light can damage the DNA
16:29 the cells. And so these melanocytes responsible for protecting the carino sites here
16:35 that they do not become damaged. they release their melanin and then that
16:41 gets absorbed by the Carroo sites. the Carides take that melanin and protect
16:48 nuclei with it. All right. that's the idea behind these two major
16:54 of cells. And so they're really of easy and there's another cell in
16:58 that we haven't talked about and I think we might get to it in
17:00 little bit here, but it's it's an immunocyte. Um It's a
17:07 now, the epidermis has five All right. So there's all carino
17:17 . But what we're looking at here different characteristics. And so whenever something
17:21 named differently, I think we've already this before. That means there's something
17:26 about it. So when you see different name, that might be a
17:29 for you to say, oh I to know a difference here. Why
17:32 this one different than all the other ? Why is this one different than
17:36 other proteins? Why is this All right. So here if you
17:41 at the layers, so this is actual micrograph. And so you can
17:45 here and then there's two tiny layers then there's another one, there's a
17:49 one. All right. And what have is if you look at these
17:53 , if you work from the basement , the lowest layer and work your
17:57 up. The first three layers are that are still in the living
18:02 In other words, they are are active and they're, they're considered to
18:08 alive. But then what happens is over as they move further and further
18:12 . So as even though these are as they move further away, they
18:16 shedding portions of their cell and then eventually die because they're too far from
18:21 nutrients. Because remember the nutrients for cells come from the blood and the
18:28 has no vasculature, all the vascular is down here in the dermis.
18:34 so the further you get away from dermis, the less nutrients you're gonna
18:38 . So you end up dying It's part of their life cycle,
18:42 instead of them dying and disappearing, maturing and becoming a unique type of
18:48 cell that serves as this outer protective . Ok. So on the surface
18:54 your skin are thick, thick layers dead cells overlying a couple of layers
19:01 living cells. Now the five all right in the Latin because you
19:08 took your Latin, right? me neither. But stratum. So
19:13 would be layer, right? And their name Bali, what do you
19:18 ? Basil? Right? Bottom What do you think? Spiny
19:27 granular, right? Lucidum, clear light, you know, they're clear
19:35 then finally, corneum. This is weird one. It's actually not different
19:41 this, but it would be All right. All right. Now
19:49 sitting on, I don't know what is. Think about. Have you
19:53 heard of someone who has corns on bottom of their feet? Right?
19:58 . So if you wear shoes with pointy ends for a long time,
20:02 gonna end up with corns, It's these hard callous knobs that protect
20:07 joints because of the constant rubbing. right. There's corn. Basically,
20:12 a hard callus area. All And so they have this corny,
20:16 hard callus appearance. That's where all these names come from.
20:20 this one doesn't. That is because the basil layer. It's the bottom
20:23 . That's where it got its but every single one of them,
20:25 the spiny layer, the granular the uh the clear layer and then
20:29 corny layer, that's where the names from. So it's not as,
20:34 complicated other than remembering which comes All right, you got five numbers
20:40 comes first, the lowest or the depending on which way you're ordering
20:44 So you just learn the order in they show up. So start with
20:47 bottom layer, work your way So what characteristics, what makes these
20:53 different from each other? That's the that you asked. All right.
20:57 , the basal layer is a deep . This is the one that is
21:01 nearest to the dermis, right? a layer, a single layer of
21:07 and this is the actively dividing This is the one that is producing
21:11 the other cells. So it's kind like I'm gonna use the word,
21:15 it doesn't mean what I'm gonna It's like the stem cell layer of
21:19 skin. OK. So as long you have these cells, they're sitting
21:24 producing more and more of these carno . All right. Now, in
21:31 of their shape, they're uh cuboidal they might even be like a low
21:36 . Now, this is a stratified . Do you see how it's stratified
21:40 layers? But we would refer to stratified epithelium as a stratified. And
21:47 look at that top layer, what of layer is that squamous? So
21:52 a stratified squamous. We don't care what the shape is. Now,
21:56 of the features you can see see how it goes up and it
21:59 down and it goes up and goes . These are referred to as epidermal
22:03 and those epidermal ridges determine the shape what's going out here, which gives
22:08 to the epidermal ridges on the surface the skin which you know as your
22:14 , right? And this allows you grip stuff, right? If it
22:18 smooth, things would slip. But have these ridges that help you grip
22:24 well. So primarily carino sites in basal layer every now and then you
22:31 find a melanocyte which has penetrated its upwards so that the Carroo sites can
22:37 their uh car or sorry, their . The next layer up is a
22:43 layer. So I'm just gonna start here. So if this is the
22:46 layer, then all this stuff up there, that is spinosa, all
22:51 . So many, many layers of . Now here, the basal layer
22:57 we said are dividing, they're the that are multiplying and creating more and
23:00 cells, the cells in the spinosa to differentiate. So the term differentiate
23:06 to change characteristics, right. So clearly becoming a different type of cell
23:12 . All right. And so they're a nondividing cell they're differentiating. So
23:18 they're no longer multiplying, instead they're their metabolic activity. Now, the
23:25 they're called the spinosa is because the here between them begin to tighten
23:32 And so the cells actually become differentially as well. They start looking more
23:37 in nature. Now, the cartoonist do a good job and unless you're
23:42 at a really good slide, you're going to see this. All
23:44 And I'm not going to sit there try to say, hey, notice
23:47 they're spiny. It's just, that's it's called. All right. So
23:51 kind of a spiky looking or spiny cell because all these desmond are being
23:57 from different directions. So it gives more of this sharp appearance. So
24:03 as you're moving further and further and away, what's going to happen
24:07 is you're going through this process of and you're starting to be deprived of
24:13 fuel that keeps you living. All . And so when you are getting
24:17 and less fuel, this is a for the cell to differentiate even
24:22 So the carino sites start producing a type of carrot called the cartoon
24:30 All right. So it's just a carrot. All right. So if
24:33 can't remember the name, just it's not just Carrot, it has
24:36 longer name to it. All And these are now visible because they're
24:41 stored up inside vesicles. And these are stained differently inside the cell.
24:48 when you do a section through the and you stain it and you look
24:51 a microscope, they have little tiny in them. They have the
24:55 So that's why it's called the granular . Now, at this point,
25:00 you start producing the car to you're no longer really kind of in
25:05 state of living, you're really kind shifting over to the, I'm ready
25:09 be dead state. And so you're get rid of the organelles you don't
25:13 . So, since you're not dividing , you don't need a nucleus.
25:17 right, and the organelles that you are gonna cease to be functional.
25:21 you might as well just get rid those too. And so you start
25:25 them and removing them so that you become the cell that you're destined to
25:32 . So the cells begin to but they have a whole bunch of
25:35 in there and they're being pushed further further away by the dividing cells and
25:39 spinosa that are pushing them up. right. And then this whole process
25:46 not be complete until you finally get that upper layer. That corneum
25:52 Now, the weird layer is the and the reason it's a weird layer
25:58 it's only found in thick skin, ? It's not found in thin
26:04 All right. Now, we're gonna to this in just a second.
26:07 just so that, you know, the palms of your hands and on
26:11 bottoms of your feet, that's thick on the rest of your body.
26:19 back of the hands, your that is thin skin. OK?
26:24 you are running and you fall and land on your hands like this,
26:29 you gonna scrape your hands really, badly? No, you might,
26:34 know, take a couple of layers and you'll be like, oh,
26:36 hurt, right? But it's, tougher. But if you were to
26:42 , say on your elbows or you , cross your uh forearms, are
26:48 gonna rip that up pretty well? . So thick skin a little bit
26:54 . And the reason it's tougher is it has this lucidum. All
26:58 it is a layer of cells that underlying the outermost layer, that
27:05 right? So what you'd be doing you'd be advancing through. Now,
27:08 you're thin skin, this doesn't So you just advance up to that
27:11 layer. And here what you're doing you're producing another type of carrot.
27:16 is a weird type of carrot called . So it's formed by that
27:20 car. All right. So just that it's a weird carrot that begins
27:25 the letter E. All right. what this does is actually serves as
27:31 thick barrier for protection, but it protects against U V light opposed to
27:39 melanin. So it's not just melanin protects against U V light. It's
27:42 lucidum. All right. Now is purpose to protect against U V
27:46 No, it just happens to do . Its job is to be the
27:49 beer, right? Protect against that . Now, you want to see
27:54 , the darker your skin, the it is to see. Like if
27:57 , I mean, it's right. , I'm, yeah, but the
28:01 skin look at the palms of your are the palms of your hands brighter
28:05 lighter than the back, right? of what? A little bit
28:10 Yeah, that's because of that lucidum the bottom of your feet are the
28:14 thing, right? It's because when V hits that it gets absorbed and
28:19 can't make it down to the lower where the melanocytes are. And so
28:25 there are no melanocytes or since the aren't being stimulated, they're not releasing
28:29 same amount of melanin that they would release. All right. So it's
28:34 another barrier to the U V in case. All right. So the
28:39 is the clear layer because you light absorbs the U V light, but
28:42 a protective bar lastly is the corneum superficial, there's about 15 to 30
28:49 of dead cells here. Um You're slowly remove the outermost layer. You
28:58 try really hard, you could sit and do this and you might get
29:01 cell or two off there, But this is a really really tough
29:05 . And part of the reason for is because of the way that these
29:08 have been dying. All right. remember what a cell is, it's
29:12 plasma membrane with stuff on the right? And so you've killed off
29:17 the organelles, you've been making So what you're left with is basically
29:21 layer of fat and a bunch of on the inside. And what they
29:26 is you squeeze out all the water now basically what you have is you
29:29 a layer of fat with protein and kind of serves like a layer of
29:33 . And so what you're doing is you're gluing cells on top of cells
29:36 they're all being held together by these desmosome. So everything is tough and
29:42 and basically being held closely closely you're waterproof because of the fat and
29:51 glycoprotein that are located within it. this is why it serves as its
29:58 barriers because of the arrangement of those . So you can do all sorts
30:04 stuff to your body, right. could pour Ebola on the surface of
30:09 skin and you'd be fine. When when do when does Ebola become problematic
30:14 it gets inside you? Right, . Disease and stuff is dangerous when
30:21 gets past the protective barriers that your has put up in front of
30:26 right? Chemical assault, physical biological assault. This is what this
30:33 layer serves as. So all this here is leading to creating this pancaked
30:41 layer that serves to protect you. five layers pretty straightforward, right?
30:49 this just kind of shows you thick versus thin. Um the the
30:53 difference between them five layers versus four . This one doesn't have the
30:58 This one is found all over your . This is on the palms of
31:00 hands and the uh bottoms of your . So the soles of your
31:05 there are sweat glands in these If you ever had to give a
31:09 . Right? And you got What do you feel is you feel
31:12 hands get sweaty, right? Or wanna hear, not like going on
31:16 coasters and your friends drag you on . See, it's really hard now
31:21 don't have Astro World here anymore. so, you know, it would
31:26 an easy question. I used to able to ask like, oh
31:27 you know, go all the time you have to go all the way
31:30 San Antonio to go hit a good coaster or I guess you can go
31:34 to Chema, right? But you that nervous stomach gets all mod and
31:38 hands start sweating right before competition. you start sweating? Not really.
31:45 , I know. It's hard to . Yeah. All right. But
31:48 mean, that's, that's kind of idea, I guess ma'am not
32:01 So itches are weird. It's, , it's a combination of stimulation.
32:06 it can be physical like a mechanoreceptor well as a chemical receptor.
32:11 and basically telling you that there is that needs to come off and so
32:15 itch is that. So, you , like, think about the easy
32:19 to think about, think about a bite. All right, mosquito
32:21 You basically mosquitoes, put in a bunch of anesthetics so that you don't
32:26 them bite you, but it sticks for a while. And so that
32:29 chemical receptors that basically say um there's wrong here. And so that's when
32:34 want to scratch it, don't scratch . Mhm Right. Because again,
32:42 , it's a perception as opposed to actual thing. That's the weird
32:47 So that type of stimulation is mostly your head than it is an actual
32:57 . Yeah. Well, so first that the itch actually exists in the
33:00 place is a perception really, it's a combination of touch and
33:03 a combination of chemical, right? to blow your mind on this because
33:08 get to it. Uh there is receptor in your body that says you
33:12 wet, right? But it's a of pressure receptors, touch receptors,
33:18 receptors. And so it's a combination those receptors being stimulated, say,
33:21 my body is wet, right? so that's kind of what an itch
33:25 . There is no itch receptor. a combination of different types of stimuli
33:30 along and saying this event is taking and you perceive the itching,
33:37 Don't scratch it. It's just gonna it worse. Um, what I
33:44 to point out here is you don't hair growing on your palms. You
33:47 have hair growing on your bottom of feet, right? So there's no
33:50 follicles, there's no sebaceous glands. , uh, in thin skin,
33:54 have those. Ok. So if have your own, just like,
33:59 know, you do have your own sheets, you may not think about
34:02 , but you have a cheat When you go in the exam,
34:05 it's OK to just kind of look and look at your body and
34:10 I learned this, right. It's be really fun, especially when we
34:14 getting to the joints because one of things I'm gonna encourage you to do
34:18 get in front of a mirror and the movements. And so if you
34:21 in the exam, you're sitting there , that's fine, right? I
34:27 , you are cheat, cheat, can do that, just don't bring
34:31 extra. And that's the idea. right. So epidermis, we said
34:39 , it protects, it protects against invasion. So first off, it
34:43 a dry surface, dry surfaces are to microorganisms. All right, located
34:50 the spinosa, you are going to a type of cells, it's sometimes
34:54 to as the ginger cell because people trying to get rid of the names
34:57 the people who discovered it, it to be called a Lager cell.
35:00 in essence, what this is is is the macrophage that is resonant to
35:04 skin. So if you wanna call epidermal dendritic, I will have both
35:08 names on an exam, right? I'm used to the old one,
35:11 lager itself. So they kind of out and when something somehow magically works
35:18 way down into it, or let's you get a cut, the lager
35:21 are stimulated to activate against any sort pathogen or damaged tissue. And so
35:26 the ones that stimulate the immunological So for example, if you notice
35:30 you get a cut, you get around that site that is because of
35:35 lager cells. Um I don't talk this all that much anymore. Um
35:43 you know, there's a lot of and wrong thinking about skin color.
35:48 so I just want to kind of it out where skin color comes
35:50 It's pigment. So the primary pigment responsible for this is melanin, but
35:56 are other pigments. So for carrot, you know what carrot
36:00 where does it come from? Yeah. Yeah. Um Also if
36:05 go get, go out and to go to CV S or something and
36:08 the tanning um lotions, you know color lotions, they, what they're
36:14 is they're providing you Kero, And so because it's a pigment and
36:18 , they're using a fat, it's fat soluble. So it goes into
36:21 skin layer. And so if you to look like, what was your
36:24 ? Suki, I can't remember. was in the New Jersey show,
36:28 . But it's a yellow pigment, pigment and basically can uh accumulate in
36:32 stratum corneum and it gives you that of darkness, that glow, but
36:36 more of an orange than anything So if you go to get a
36:39 on tan, that's what they're spraying with is the care team. All
36:43 . But with regard to melamin because know, it can become a major
36:48 uh in some areas and, and truth is is this and this is
36:52 of weird is we all produce the amount of melanin. We have the
36:56 number of melanocytes. The difference is in the pigment itself. So the
37:04 we have can be what is called and pheo melanin. The U melanin
37:08 more of a black or brown pigment the me is more of a
37:12 yellow pigment. And so we also varieties of that. But the easy
37:16 to see this is look at your colors. I mean, how many
37:19 types of hair colors do we I mean, just keeping it
37:22 we have blonde, we have ginger red, we have brown and all
37:30 variations, we have auburn and all variation and we have black hair,
37:34 is in all of its variations. right, hair is a, is
37:37 derivative of skin, right? And it's the same pigments. And so
37:42 can imagine how do I get blonde ? Well, melanin, how do
37:45 get ginger hair? Well, it's different type of melanin. It leans
37:49 different way. How do I get hair? Well, I may have
37:52 melanin but it's primarily melamin. How I get black hair? It's primary
37:56 and it's on that blacker scale. not just two pigments there, these
38:00 groups of pigments. All right. we have the same relative number and
38:04 should have said it's not the amount pigment we produce. It's,
38:08 we do produce more or less depending all sorts of encoding, right?
38:15 it doesn't matter if you're dark skinned light skin, you have the same
38:17 of melanocytes and then as you expose to more and more light, you're
38:22 get your or more U V you're gonna produce more and more of
38:26 melon in itself, depending upon much of melon you produce. So if
38:30 spend all my time in the am I going to be a pale
38:33 or whatever color color we want to this? Huh? It's a little
38:40 . Thank you. Yeah. So want you to imagine me and my
38:44 . So many, many pounds. I had awesome California blonde hair.
38:54 was just waiting for someone to I really did. I mean,
38:56 was awesome. Right. And I've these blue eyes. I mean,
39:00 go to the pool all summer man. I look like a surfer
39:06 . My hair wasn't flowing though yeah, because we talked about how
39:10 my hair already was. All So that darkness is a function of
39:17 the melons. So here's your melanocytes producing it. And then what they
39:21 is the carino sites pick that stuff and they create kind of this
39:26 So if you can imagine the they take that and they accumulate the
39:31 over the nucleus so that the light that pigment, the U V light
39:35 absorbed so that the nucleus doesn't get by the U V light and cause
39:40 damage, which is bad. That's whole function. All right,
39:46 If you got freckles, if you pigmented moles, those are the same
39:50 . The difference is that the melamin accumulating in a single spot,
39:54 Rather than spreading out throughout the entire . And you got plenty of these
39:59 produce enough to protect your skin. cool with this skin color where it
40:07 from. So where did it come ? Pigments? What kind of pigments
40:12 we produce stuff we can absorb Team being the big one. All
40:18 . Well, one of the things your skin does is it can detect
40:21 environment around it. And so there receptors of different types of various types
40:28 are associated with the epidermis, but not directly part of the epidermis.
40:33 . In other words, the nerve themselves, you will get some that
40:36 through, but for the most they're associated with the dermis. All
40:40 . So the, the big the key one to understand is what
40:43 called the tactile disc or the Merkel is what it's what it's called.
40:49 again, they don't show a really job. But in essence what it
40:51 , if I went down to the layer here, you might see a
40:55 cell that is called a tactile This is not what I'm just pointing
40:58 this cell to make pretend, let's this is a tactile cell. Well
41:02 with that tactile cell is a nerve that would come up right to it
41:06 be associated with that tactile cell. so it's a tactile cell that detects
41:11 change in the environment. So it's mechanoreceptor and what it does is any
41:18 of manipulation of the skin is going be detected in that cell and then
41:20 sent along that fiber. So what saying here is see those little bumps
41:25 the end notice they're in the But the little dot which is supposed
41:29 be pointing to them that's actually where tactile cell, it's in the
41:32 Tactile cell is in the strata. nerve is, excuse me is in
41:37 dermis. It deals with the question fine touch and uh very, very
41:43 simple pressure. So not deep but light pressure. We also might
41:49 free nerve endings, these may penetrate . So these would be pain,
41:52 touch, tickling is a form of just so, you know, um
41:57 then itching, that would be the stimuli. So that's in the no
42:01 . Um those would be associated with epidermis, the rest of them and
42:06 will get to them in a little are going to be found in the
42:10 layers, the dermis. Now, you've been paying attention, have you
42:16 that we just kind of walk through functions of the epidermis on that one
42:22 ? You remember if you go back look at that one slide, you'll
42:24 , oh, here are the function now actually just going into the details
42:26 each of those things. And so we said that one of the things
42:30 the epidermis does, it has metabolic , it's responsible for producing vitamin
42:35 So how do we produce vitamin D put, there's cholesterol that's found in
42:39 layers. U V light comes along a change in the shape of the
42:45 . So what we do is we that cholesterol, we create what is
42:48 vitamin D three. So, when take those vitamins, right? And
42:52 have vitamin D in it, this what you're taking. Is this
42:55 uh colier the Calciferol now can be through the body. And what it
43:02 is it goes to the liver and gets modified, then goes to the
43:05 gets modified once again and it gets into its active form. So we
43:09 vitamin D at this point, uh , right? So it's just a
43:16 of this. So it starts up the skin, start with cholesterol,
43:21 modify it. And then all those . And now what it does,
43:24 helps us to absorb calcium from our to make our bones stronger. Does
43:33 surprise you that we put it in ? Right? You know, your
43:40 is fortified fortified with two vitamins, A and vitamin D, right?
43:45 are fat soluble vitamins. We put A in so that you can have
43:50 vision because you'll learn a little bit . The molecule that helps you with
43:55 , it's called retinol. And if take a vitamin A molecule cut it
43:58 half directly, you end up with retinol. All right. Vitamin A
44:02 care? Vitamin D allows you to calcium, makes your bones strong.
44:08 you remember the commercials watching when you younger? Right? The little kid
44:12 up to the cute woman or the girl talking to the, the bow
44:15 . Do you remember those commercials. , when you consume calcium, vitamin
44:22 helps you absorb the calcium milk has in it might as well give you
44:27 D right there. So you can start doing the work milk does a
44:32 good. So that's everything you need know about the epidermis. But we're
44:40 to ask how many layers five do of them have unique characteristics? Should
44:47 know them probably right? Functions pretty types of cells, how many
44:58 two major cells? And then we that weird cell. So that leads
45:03 into the dermis. All right. the epidermis is this outer layer,
45:08 ? So here's your epidermis. You see the epidermal ridges really, really
45:12 there being associated with those ups and the epidermal ridges that are near the
45:19 . But really what we also refer these as on the other side.
45:23 if this is the epidermal ridge on opposite side, you have a dermal
45:28 , what is a paille? It's a finger, right? And
45:32 you can imagine here is that you this layer that's so this this layer
45:37 epithelium that's sitting on top of this tissue layer. And these fingers are
45:41 are interlocked like. So we're looking in two dimensions. So we only
45:46 where we've made that cut. But can imagine it's not just this
45:50 it's also this way. And so think of those egg carton mattresses.
45:55 you familiar with the egg carton mattresses all those things that are poking up
46:00 your back and it just covers the mattress. That's kind of what it
46:05 like all the way through here. so if you interlocking both those
46:08 this stuff just doesn't move. So, like, like this,
46:15 ? And then like that all the around. So we have two different
46:21 to the dermis. There's gonna be lot of vasculature, there's gonna be
46:25 lot of lymphatics. We'll learn about and A MP two. But
46:29 it's like the vasculature, all And this is where the nerves are
46:34 be lo located as well are down in the dermal layer. And I
46:38 this artist kind of does it good . And this, I think it's
46:41 artist. This might actually be a AAA scan uh you know, in
46:46 micro histological thing, but you can of see here, there's this little
46:51 , right? That's kind of So everything above that where the fingers
46:57 , that's called the papillary layer. associate the pail and everything below that
47:03 the reticular layer. So this is all the network and the meshing is
47:06 . So what we do is when look at this, we kind of
47:08 it up into these two different areas the pap layer, right? We're
47:14 have a connective tissue. All This is where if we're up in
47:20 , this is where you're going to the capillary loops. You'll see the
47:22 nerve endings work up there. So is where you're going to see pain
47:25 touch receptors. And these are how kind of describe they're interlocked or inter
47:31 . So that the two layers, epidermis and the dermis are interlinked and
47:39 . You can't tear away the skin causing a great deal of damage to
47:43 dermis itself underlying that is the reticular . All right. So here we're
47:51 have dense irregular connective tissue. All . So we have a on the
47:57 , which is what we, when think of it connective tissue, that's
47:59 of what we think of. But we're getting into this dense irregular.
48:02 we have a lot of collagen and kind of running in a specific direction
48:07 gives rise to what are called cleavage . All right. So a cleavage
48:12 is kind of what you're seeing All right, if you know,
48:17 this is kind of showing you the in which the direction collagen normally
48:22 And these are really, really beneficial a cleavage line um allows the doctor
48:28 physician when, when you are having . If I cut along the cleavage
48:32 , what's gonna happen is is that wound is regulat. In other
48:36 I can open and close it and do a lot of damage to the
48:40 . But if I cut opposite the line. So for example, if
48:43 cut this way, the the the collagen pulls and kind of causes
48:48 wound to open up even further. , kind of the same thing with
48:52 body. If you wound yourself, want to kind of wounded and hopefully
48:57 with the cleavage line, you don't it to go the opposite direction because
49:00 a real nasty thing to kind of right now. This is cartoon kind
49:05 gives you a better sense. So you can see here's the blood vessels
49:09 then here's the capillary as they move and then they get right up in
49:12 and near the pap pap region, ? So here in the pail,
49:17 , you can see and here's free endings um up in those deep
49:21 But then down here, you can there's still vasculature, right? They're
49:26 vessels that are providing nutrients to the environment and and allowing that stuff to
49:32 through you have nerves and different types receptors located deep within the the dermis
49:40 . And these blood vessels allow us like I said to move temperature around
49:47 bodies, right. When we're we move water near the surface.
49:51 it's going to come into this capillary and we're going to bring the heat
49:55 the surface so that it can be from our body. And when we're
49:59 , we constrict those vessels and it the fluid away from the surface.
50:03 the heat doesn't escape from our bodies we bring blood close to the
50:08 What does your skin do? I , in terms of a physical appearance
50:15 red, right? When you're right? Or if you're running or
50:21 that flushing of the skin is those in this layer, vasodilator. So
50:28 brought the blood near the surface and why your skin is turning that reddish
50:36 . The other thing that we have in the particular layer. So different
50:40 the cleavage line is a flexure all right. And this are folds
50:45 the dermis that basically are are pushing and then connect to deeper structures in
50:50 body. So this is a picture the palm of someone's hand and you
50:54 see those those are easy to right? But you got flexure lines
50:57 over the place, right? I , here's a flexure line right
51:01 And this allows me to move without skin doing weird things, it holds
51:05 skin in place so that I can whatever the function of that of,
51:10 that part is, right? And can look all over the back of
51:14 knees, the bottom of your feet all your digits, right? And
51:20 the older you get, you get lines around your mouth, you
51:24 can make a lot of expressions. mean here it's flexure line right
51:27 I'm just trying to think of things you probably don't think about,
51:30 So it's deep in the dermis and just folds to allow the skin to
51:35 without bunching up and creating weird uh skin that gets in the way
51:41 of functionality. Now, I'm not pretend this part right here is
51:47 It's just memorization. So you have memorize this stuff. OK? Um
51:53 we're looking at here are different types receptors of the dermis. All
51:57 And again, they're named differently, discovered by different people. And that's
52:01 the names come from. And so will see on the exam, I
52:04 give you the, the, the long term name as well as
52:07 current name, right? Because I they're trying to get rid of,
52:11 epi nomenclature. But in essence, I wanna do here is that there's
52:17 three different types of receptors and we're come back to them again. So
52:20 get tested once and then a little on in the semester, you'll get
52:23 again. But what I wanna do I wanna just show these to you
52:27 these types of receptors that are found the dermis. And the reason I
52:30 this is not fun because I hate stuff. It's like my, the
52:33 of my existence. And so you memorize these and you move on.
52:37 right. So Mesner, uh uh sorry Meisner core puzzles is going to
52:44 found up here in the dermal So you can see right up
52:48 So these are really, really near surface. So if you're near the
52:52 , what are you trying to Well, you're detecting a light
52:56 you're detecting a light pressure and you're vibrations in those outer layers.
53:02 what do you mean vibrations when you that? Well, when you're grabbing
53:06 and holding on to stuff, if run your fingers to cross a
53:09 you feel that movement because there's this vibration that's taking place. All
53:15 And so that's what Mesner core puzzles responsible for, right? Moving further
53:24 , we're gonna see ruin's core All right. So ruin's uh core
53:30 down here. These are bunches of . So what happens is, is
53:34 type of receptor has collagen in it then the fibers are wrapped around it
53:37 then you wrap more layers of collagen it. And so what this does
53:41 it detects pressure and skin distortion in middle layers. All right. So
53:48 , think about like, you the Indian burns and all the horrible
53:51 that your siblings used to torture you or maybe you tortured somebody with,
53:56 ? The idea of manipulating the skin be felt deep, right? It's
54:02 the deepest but midway through. And it's the stretching of the collagen is
54:06 you're detecting with. Ruffin's core All right. So that's that middle
54:11 and then you go furthest down and the lowest layers in the deepest parts
54:17 the dermis. This is where the corpuscles are all right. And so
54:22 uh structurally, they're different than what see here in Mesner. Now,
54:26 cartoon is not going to show this basically what it is you have a
54:29 and then what you do is you wrapping layers and layers and layers of
54:33 tissue around this structure. And so this is the deep pressure and the
54:39 vibrations that you'd feel. So, other words, you know, if
54:42 comes along and digs their finger into skin, that that deep feeling of
54:48 is detected beyond the ners, the , stop noticing it. And now
54:53 start noticing that pressure, deep So this is like, you
54:58 when we're sitting well, I'm gonna the example. So if you notice
55:02 been doing a lot of construction over next to my building, right?
55:06 you can feel them jack hammering in building that deep, right? Or
55:12 you're driving along and a car that , boom, comes by the
55:15 boom, boom and you're gonna feel in your bones. You know,
55:18 tell you, I feel it in , that's Pacinian core puzzles. That's
55:21 feeling that deep vibration. All So, you know, it's not
55:28 but it's still something you have to . So the good news is that
55:34 makes sense, right? Light light pressure, you know,
55:41 deeper manipulation. And then finally down , the deep touch, the deep
55:46 . Ok. That kind of, makes sense. Sort of.
55:55 that's everything you need to know about for right now. I mean,
55:59 when you go on, someone's gonna you learn something else. Any questions
56:03 the skin? Really? OK. wanna talk about here, we were
56:15 about here earlier. All right, is basically strands of dead crain
56:25 So it is the same thing that is, it's just differently organized.
56:30 has a different carrot in it. what we refer to as a harder
56:34 . So if you feel your hair if you pull out a hair uh
56:37 start playing with it, you'll notice it has kind of a, a
56:40 to it. It's really hard to actually a relative to the strength that
56:46 had that it is or the So the other thing is the way
56:51 the cells are arranged are overlapping like . And you can kind of see
56:55 this picture here, they're kind of scales on top of scales or shingles
56:59 . So let see if I do this way. So you have one
57:02 then the next cell is like on of it like this and the next
57:05 is on top of it like so on and so forth. So
57:08 can't just pull a cell off with skin where the cells are like
57:12 And so the scale a hair or cell can flake off here. It's
57:16 , much more difficult for that to . I love this next slide because
57:25 is the purpose of hair? All , hair has a protective function.
57:31 right. First off, it prevents and injury. Um That would be
57:36 the surface of your head. This where I get to tell you that
57:38 went to a concert once in the of the desert in El Paso over
57:42 summer, it was one of Stevie last concerts. So if you know
57:46 Stevie Rayvon is, um the concert supposed to be like at four
57:49 me and my buddies, we go in our truck, uh One of
57:53 friend's trucks. We bought a whole of beer and we started drinking,
57:56 around, oh, I don't seven or eight o'clock in the morning
57:59 we drank and drank and drank and became horribly dehydrated. So about two
58:04 is when we ran out of our and we're like, all right,
58:07 gotta get to the concert. We showed up to the concert, you
58:10 , go in there. I'm like there at the front of the stage
58:14 he comes out and starts performing and a uh a biker gang fight breaks
58:18 and people are getting pressed up against thing and they're actually passing people over
58:23 , the gate. I'm like, done with this. I go back
58:26 the very end of the back of stadium. Watch the rest of the
58:29 . Ok. I'm good to go we get back to the car,
58:32 home, dehydrated, sun, tired, exhausted. It was a
58:37 day, but it was a good . But one of the things I
58:41 because we've been sitting out in the bed of a truck all day,
58:45 scalp was burned, the tops of ears were burned. So this serves
58:51 a good protective area. Have you sunburn on your head? I
58:54 you spend some time outside. Have been sunburn on your head? Not
58:56 much though. Right. Yeah. . Spend a couple hours outside.
59:01 gonna feel that sun, it's gonna its way through that here. But
59:04 the most part, it does a good job of preventing that from
59:10 The older you get, the worse hairs get, you have hairs growing
59:15 your nasal cavity. You have hairs in your ear. The purpose of
59:18 is to trap particles. Those hairs pointing outward. They're like big giant
59:22 , you know, like in the timey forth where they have the stakes
59:25 out to prevent the people from coming the walls. That's kind of what
59:28 hairs do, they point outward and prevents small organisms from getting into those
59:33 and small organisms include spiders and If you go on youtube enough you'll
59:37 able to find a video of someone has a cricket stuck in their ear
59:40 spider living in their ear. horrible stuff. Yeah. Um,
59:44 we live in a first world, a third world. And that's usually
59:47 you see that stuff happening. this is cool. Um, your
59:52 , you have hair above your everyone here has hair above your
59:54 Yeah, that's your natural sweat Have you noticed that? Go and
59:58 at, you know, go and at your eyes in the mirror.
60:01 right, and look at these eyebrows look at how they're shaped. Notice
60:05 the shape of the eyebrow is to inward towards the nose and then back
60:10 towards the eyes. So when you , right, that hits that
60:14 those hairs push that fluid, that inward away from your eyes and outward
60:20 from your eyes so that the sweat go rolling into your eyes. All
60:25 . The other thing that we do we have little eyelashes, we can
60:28 a whole bunch of time talking but it basically sits there and those
60:31 serve his fans to brush and prevent from going into your eyes. And
60:36 easy way to test this is take finger and start poking someone towards the
60:39 and watch how quickly their eyes slam because those little hairs, the moment
60:43 feel any sort of, of pressure cause your eyes to close this one
60:49 using for fun. You guys know this guy is? Phil Specter.
60:55 Specter was the guy who was the of many of the Beatles albums.
61:01 uh he was in Hollywood and he he was God. Uh like everybody
61:05 Hollywood thinks they are that they can away with anything. And so,
61:09 I my recollection is that he was tried for attempted murder at the time
61:17 , I may be wrong. But essence, what happened was he had
61:21 model over at his house and basically sex and she said no. And
61:26 he put a gun in her mouth threatened to kill her or something like
61:29 . And so he was put on for that and he showed up with
61:32 hair like this. Now it wasn't big. It was actually like
61:36 someone photoshopped it to make him look . But basically his, his defense
61:40 , it wasn't my fault. I crazy and with hair like that,
61:44 course. Right. But if you hair like that, would you retain
61:50 ? Yeah. So think about bears cats and dogs and all your pets
61:54 stuff like that. And in the time, what does their hair
61:57 It gets thicker and when they get , they poo their hair out and
62:01 you get cold, you poop your out. Have you ever gotten
62:03 And you get goose bumps and your stick up on end. You just
62:07 have a lot of hair, but body is trying to do what all
62:09 mammals do, which is basically trap near the surface of the body under
62:14 layer of hair. Ok. we use it for sense of
62:19 Ever have an animal like a spider on your body and you feel
62:22 you know, that's because this is other part where I tell. So
62:25 grew up, I, I hesitate tell you how old I am.
62:28 grew up a long time ago back they had shag carpets. You
62:33 shag carpet is, if you go your grandma's house, she may have
62:37 carpet still. I don't know. are these horrible, terrible ideas from
62:42 seventies. Anyway, I was over this girl's house, her watching
62:45 show I'm up on, you she's up on the sofa, I'm
62:47 the ground and I grew up like . I grew up in El Paso
62:50 I'm sitting there like on the, the ground, my elbows on the
62:54 , I'm watching whatever the movie is I feel something on my arm and
62:57 kind of brush off, you I'm sitting there and I feel it
62:59 my arm again. I brushed off . Finally, third time. What
63:02 on my arm. It was a trying to cut up on my
63:06 How do I know it was Well, it was because the hairs
63:09 my arm were detecting as it was to find its way on.
63:14 we caught it and put in the or not in the trash in
63:17 in the toilet and flushed it. , we use it as visible,
63:21 identification. First thing you did when , when you saw me was what
63:25 asked me, did you get a ? Because your mental image of who
63:29 was is defined by my hairstyle. one of the very first things we
63:34 . So the moment someone gets a , it's like I have to recalibrate
63:37 way that I look at you because no longer the way that I
63:40 If you see someone from behind, like, oh, I'm looking at
63:44 back of their head. How do know who they are? I know
63:46 by their hair. We also use as a way to determine age as
63:50 as sex
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