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BIOL 2301 Human Anatomy & Physiology I - BIOL2301_lecture16_1019
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00:05 All right, good morning y'all. today we begin, we begin
00:11 our journey through the nervous system. So, uh from here on out
00:18 the end of the semester, everything do is nervous system. Uh What
00:22 gonna do today is we're going to ourselves to uh just a couple of
00:28 of concepts. We're gonna look of nervous system. Uh We're gonna look
00:33 little bit, we're gonna just, and then look at how uh are
00:40 arteries uh that provide blood to the and we're just gonna keep. So
00:46 gonna be a little bit of Actually, there'll be a lot of
00:49 , but uh the front end is more of a, let's try to
00:53 how we uh organize the system. , there we go. That's what
00:58 looking for. All right. So we talk about the nervous system,
01:02 say there's basically two parts to We have the central nervous system and
01:06 peripheral nervous system. Now, everything going to talk about when we talk
01:09 organization is just to make it easier us to understand this, uh this
01:15 this whole system together, all Um As humans, we like to
01:20 things in boxes, like we like label things and say this is what
01:23 is. And so we just do and that's really what's going on here
01:27 that we were learning and discovering different of the or the different, the
01:33 uh functionality of the different parts of nervous system. It was like,
01:37 , there is a hierarchy, there's organization. So that's kind of what
01:41 first level is is saying, we have portion that is responsible for
01:45 information. And so that's the central system. All right. And the
01:49 nervous system is your brain and your cord and it keeps it nice and
01:53 . So anything outside of the brain spinal cord is not central, it
01:58 peripheral. Now the peripheral nervous system nervous systems or sends information. So
02:06 idea is that I can detect things environment or from my internal environment in
02:12 process of that would be the peripheral system doing that job. It takes
02:16 information, send it up to the system processes. Did it have to
02:21 the brain to process information based on that slide says? No. So
02:29 the spinal cord? OK. Now information, once it's processed is gonna
02:35 a response back out to some sort structure to create a response. I'm
02:40 give a real simple one. All . So if I step on t
02:43 am I gonna do with my I'm gonna pick it up. All
02:46 . So me stepping up, that be peripheral, that information up to
02:52 spinal cord, there's a, it lift your foot up. And so
02:58 message that would be again through the nervous system. So the processing,
03:05 , peripheral nervous system, sending or information. All right. So in
03:13 peripheral nervous system, the structures that gonna be seeing are what are called
03:17 and ganglia. Now this is gonna like a statement or uh something that
03:22 on as a trick question. Are nerves in the central nervous system?
03:28 at the slide, will it say , there are no nerves in the
03:32 nervous system. Nerves are simply structures are passing between two points.
03:39 We will get to this in more , but I want to make that
03:42 right now is that you do not nerves in the central nervous system.
03:46 fact, nerves are characteristic of nervous . All right. And we get
03:51 gangly, we'll deal with gangly. right. So there is a certain
03:57 principle to the central nervous system. , if you're like me, uh
04:02 like to start organizing things, you'll like the drawer, you'll start putting
04:05 in nice and neat. And after 30 seconds you get bored, you
04:08 shove everything in there. That's good . All right. Sound like does
04:12 sound. OK. All right. central nervous system, peripheral nervous system
04:16 highly organized. It is not like Wayne is. All right. So
04:21 we're going to see is there's going be a hierarchy of organization. That
04:25 there are what we refer to as order structures and order structures, lower
04:30 structures, send information, higher order where further processing is done. All
04:35 , an example here would be, example, when I said I stepped
04:39 on that tack and I lifted my up, that would be lower order
04:43 because that's a reflex, right? don't have to think about lifting up
04:46 foot. It just happens. But I step on a tack, how
04:50 I proclaim that I've stepped on a , which is one of the things
04:54 would say. So I perceive the , I vocalize the pain, all
05:01 upper level stuff is perceiving and and vocalizing. All right. So the
05:08 would be lower level at the level the spinal cord, but information is
05:11 up further for further processing. So is a larger responsiveness to it.
05:17 , it's not always going to be case. Sometimes things just stay at
05:19 lower. But if you're thinking about that's higher order, OK. Second
05:26 there is a structural and functional pattern organization and what that literally means in
05:32 is that are of like things or similar functions are grouped together so that
05:38 work together. That seems stupid to , but sometimes we have to say
05:42 plus one equals two. All So the idea here is that when
05:46 are looking at the nervous system and looking at its start noticing is,
05:51 , this is an area that processes skills or motor activity. This is
05:56 area that process sound, this is area that is responsible for speech.
06:01 idea is again, it's not like everything in the central nervous system that
06:09 that yeah, and that and carries so that there is a topographical
06:18 Now, if you don't know the topographical means it means that there is
06:21 map that is preserved of the body the brain. OK. Now we're
06:28 maps would go to the special senses the. So that's gonna be unit
06:32 . But for example, I want to think of like a keyboard for
06:35 piano. You guys could picture that if you ever to play the
06:39 can you picture the keyboard on one of the keyboard? We have high
06:43 on the other side of the we have low notes and I might
06:45 had those two switch because I don't the keyboards, all right. But
06:49 the auditory cortex, for example, is organized along that organizational path because
06:58 ear is organized along that sound path high notes versus low notes. That
07:05 of sound interesting. Your brain, activity being processed. In other
07:11 the signals that go out and tell where to move your arms and legs
07:14 stuff is organized app that follows your more or less that you would basically
07:22 if you map it. I was , oh, it kind of looks
07:24 a body because the hands are over this side, the feet are on
07:28 side and you can just map it the line. Now, we'll see
07:32 in greater detail. But I wanted to understand there is a organization to
07:36 . It's not just random fibers moving uh random parts of the brain with
07:41 hopes that something's gonna work. The thing is that the central nervous system
07:47 plastic. Now, when you hear , remember what we said, plastic
07:52 that it's changeable. All right. so what you'll see is as you
07:57 skills, as you process information, you uh as you work, things
08:03 when you're studying, when you experience new, your brain reorganizes the interactions
08:10 individual neurons that are found in the nervous system. And so it organize
08:16 and reorganizes itself over and over and again to ensure that things.
08:24 there was a movie a long time when I say a long time
08:27 probably within your lifespan, but probably you were little kids. All
08:31 it was called and I'm never gonna the name right, because I always
08:34 up. But it's like something of spotless mind sunshine of the spotless
08:38 Jim Carrey. Here's the principle of movie guy to girl break up,
08:43 wants to forget that she ever uh dating this guy. And so she
08:46 to a company that is able to memories. All right. Very interesting
08:51 . But the idea is, is the memory is trying to hide itself
08:55 the brain. And so it's like around. And so the principle here
08:59 that, oh I can go to specific neuron and zap it and you
09:02 a memory. That's not how the works. A memory. An idea
09:06 process anything that you do is a of neurons firing pattern. And when
09:12 repeat that pattern, that memory, skill, whatever is repeated. All
09:17 . And so what I'm saying here that in order to get that pattern
09:21 have to create pattern and then you the pattern. And that is how
09:26 say it's plastic, your brain is because it continually reorganized itself to ensure
09:31 the patterns are being preserved. All . Now, I see a couple
09:35 people not here go. This is very, very deep concept. We'll
09:38 to it later, right? But idea is OK. The the brain
09:42 not, you're not born and it's and it doesn't ever change, it
09:46 all the time is the key thing walk away from here. All
09:52 So the first thing anatomically speaking is want to look at the central nervous
09:58 and most of the stuff we're gonna with today is central nervous system.
10:01 right. In fact, I think of it is the first thing I
10:05 you to understand is that when you at the central nervous system, you're
10:08 two different areas that look different from other. And when they first started
10:13 looking at things they said, here's an area that's dark and here's
10:16 area that's light. We're gonna call the gray material, we're gonna call
10:20 other the white material. All So it's gray matter and white
10:24 All right. Now, what these are, are areas of different concentration
10:30 material that represent different parts of neurons are located in these specific areas.
10:36 because they're the different parts of the , that means there's different activity that's
10:40 in these areas, the gray And so we're looking at over here
10:44 the left side, we have up is the cerebrum. So that would
10:47 what you think of as the And then we're going to look at
10:49 parts and, and you can see the little tiny picture showing the whole
10:53 , you can see where the slices . So the gray matter is found
10:58 all of the central nervous system as the white matter. And So you
11:02 see down here at the very bottom spinal cord and very, very top
11:05 would be the higher order cerebrum. . So what is gray matter,
11:10 matter is where you're gonna find the bodies of neurons. So if you
11:15 of a neuron as being the cell and the dendrites and the axon,
11:19 you're talking about gray ma matter, talking about those cell bodies plus the
11:23 around them. All right, white . On the other hand represents the
11:29 . All right. And so what looking at here is gray matters where
11:34 is being processed. White matter is where you're sending information between two parts
11:40 the brain. And if you look the central nervous system, you'll see
11:44 the most part, there's a specific to it. We're gonna start down
11:49 and we're gonna work our way a bit upward here. All right.
11:53 if you look here the spinal the way that the organization works is
11:58 the outside is mostly white matter and on the inside, that's where you
12:02 gray matter. And when we talk the spinal cord, we'll go into
12:04 depth here, but it kind of like a butterfly, right? I
12:07 , you can see it kind of like a butterfly kind of, I
12:10 you have to squint maybe you make blurry. OK. So here center
12:16 that, you'll see a little tiny , which is trying to show the
12:20 canal. All right. But as move up, you're gonna get more
12:24 more processing. And so when you arriving in the structures that make up
12:28 brain. So for example, in brain stem and then further on uh
12:34 , there's not enough space internally for matter. So what we do is
12:37 put on the outside. So spinal , we have gray matter surrounded by
12:44 matter in the cerebrum, we have matter surrounded by white matter, surrounded
12:50 by gray matter. So there's the . All right, the way you
12:54 think about it is the cerebrum is an Oreo, it's dark light
12:57 OK? So there's a lot of takes place in the cerebral. We're
13:02 figure out later, most of your is done up there. OK?
13:07 part about the nervous system, your system is thinking about it. So
13:12 is that it precedes it cool. right. Now in the cerebrum,
13:27 ? You have these internal areas of matter and we have a special name
13:32 them. All right. So on outside, I'm gonna, I'm gonna
13:36 say we refer to the outside of as a cortex. So when you
13:40 cerebral cortex or cerebellar cortex, it's referring to the gray matter on the
13:45 . All right. But when you down deep, there is no medulla
13:48 instead, what we do is we to the gray matter as being
13:52 Now don't confuse nuclei in this context the the little tiny dot inside of
13:57 cell, right, that central processing inside a cell, we're talking about
14:02 and bunches of cells grouped together, ? So that's what a nucleus is
14:07 the context of the nervous system. right. So when you hear basal
14:12 , it's specifically pointing out a group gray matter that's found in the
14:18 And again, we'll get to that when we start talking in more depth
14:22 these things in the uh let's what else did I want to point
14:28 ? Oh Yeah. Um No, was actually it. Uh so gray
14:32 versus white matter, gray matter and information, white matter, I'm sending
14:36 between points of gray matter is really that boils down to. Uh The
14:41 thing I would say, white the easy way to remember that is
14:44 represents my Ellen. That's, that's it's white because it's my own
14:50 My Ellen is primarily fat. So you think about what is fat,
14:54 about a rock that is white. that's an easy way to remember
15:01 So, structurally, what we want do is we ask the question.
15:04 right, the central system is pretty for you just to exist. And
15:10 things that are important, would you with that? I mean, your
15:16 protected. Right. Right. We structure protect uh uh development and growth
15:24 , of a pregnant that would be hips, right? And then we
15:28 protection for our brains, right? it's not just the hard stuff that
15:33 be like the first layer of we have four different layers of
15:37 That's really what the majority of this is gonna be today is what,
15:40 do we protect this structure, this nervous system? So the first part
15:45 gonna be bony. So case of brain, it's gonna be the
15:49 And when we talk about the spinal , it's gonna be the vertebrae.
15:51 right. So that's, that's uh first level of protection. And you
15:55 see in our little cartoon, that's we're trying to show here here is
15:58 we're gonna ignore the skin and the uh the subcutaneous layers. So there's
16:03 , there's your bone right there. then once you get down beneath the
16:07 , have some other things that are kind of important. The first thing
16:11 we're gonna have a series of They're called collectively the meninges. Similar
16:17 meninx. Meninx. All right. there's gonna be three different meninges that
16:23 that underlie the bone and are overlaying uh uh nervous tissue of the central
16:31 system. And then also within those , we're gonna see a protective barrier
16:37 made up of fluid. This is fluid, all right. And it's
16:43 layer. All right, water is incompressible and label, but it also
16:48 move materials around. And so these anatomical structures. And then the third
16:53 is anatomical and physio or the fourth is anatomical and physiological. And this
16:58 is what we call the blood brain , usually abbreviated DB B. All
17:03 . Now, the blood brain barrier a physical barrier. So it's anatomical
17:08 we'll describe this, but it's also and what prevents materials that shouldn't be
17:13 to the brain from going to the and keep the brain from leaving the
17:20 . So if you want to right , the carriers allow that to
17:26 So it is a limiting uh uh barrier. And we're gonna go through
17:33 of these and our starting point because already talked the bone. So you
17:36 about the cranium and the vertebrae. what I do is I want to
17:39 here with the meninges. All Now, these three layers,
17:44 what we do when we look at is we're gonna go from the outside
17:47 the inside because that makes sense, ? If you're cutting into something,
17:50 gonna work out right way in. so if you're working outward,
17:55 we have the dura matter, we the arachnoid matter and then the last
18:01 , the nearest one to the surface the skin or sorry, the surface
18:05 tissues. I have sort me, flip it around, I have P
18:17 so I have a protective and so how I remember it. OK.
18:22 I'm doing opposite. So I We're gonna go from the inside
18:26 Is that OK? All right. starting with the pia matter. Now
18:35 , here we are in our This right here represents nervous tissue.
18:38 , you can see the cerebral this is the white matter underlying it
18:42 right up next to the surface that down and up and down and up
18:49 down and is adhered very, very to the surface. This would be
18:53 pia matter, it is very thin it is closely adhered to the
18:58 All right, it's like you shrunk this really thin membrane against the surface
19:04 the of the brain. Now, this structure, it is highly,
19:09 vascularized, meaning that there are lots lots of that are found within the
19:16 matter and then penetrating down into applying blood to the tissue underlying it.
19:25 the pia matter and vascularized closely adhered upward, we have another structure.
19:35 if this is the pia matter, bluish layer that they're trying to show
19:40 the cartoon would represent the arachnoid Now, when you hear arachnoid,
19:45 do you think of spiders? So that's what I think of too
19:51 now, just underneath the arachnoid It's not right next to the
19:56 there's a, there's a space underneath arachnoid layer. So you have the
20:01 matter you have the pia matter and you have the subarachnoid space and if
20:05 look in it, what you see you see a lot of connective tissue
20:10 , what are called tra if you in there, the spider web,
20:15 ? And so that's where it got name from. And I just like
20:18 remember the subarachnoid space is where the spiders live. Yeah. Writers and
20:24 like in the room and you're I don't know why I'm here.
20:28 . OK. That's because the brain attacked and stop trying. What's actually
20:36 the sub arachnoid space is cerebral spinal . So we said that within the
20:41 of the, we're going to see fluid. So if you have the
20:44 matter adhered right next to the brain you have this arachnoid matter that's creating
20:50 space in that space. Is that of fluid that is cerebral spinal
20:55 All right, we're gonna talk about it gets there and so on.
21:00 one of uh that penetrate the sub . I'm just going to see if
21:05 can find a picture. Yes, do right there. All right.
21:08 jumping up ahead just to show you picture of what Arachnoid Villa. So
21:12 here. It's labeled as a There are two different times what's big
21:16 . Small Avila is small. A is big but they're the same
21:20 It basically is a structure of the matter that penetrates upward and into or
21:26 the dura. OK. So when see them, this is what you
21:30 be visualizing. So the, the me with that color, what is
21:34 turquoise? You're gonna call that OK. We're good with turquoise.
21:37 right. So where the turquoise that would be the subarachnoid space,
21:42 black line that is the boundary between turquoise and the dark blue. That
21:46 be the arachnoid matter and there would dura there as well. And what
21:50 doing is that, that villa or is a bubble that pushes up through
21:55 brings that um that uh subarachnoid space through the dura so that the fluid
22:04 then leave and join up with the in the venous portion of the nervous
22:10 . All right. So going back the slide, it penetrates through the
22:15 and projects into the structures called the sinuses, which is part of the
22:20 system. All right. And for one have a picture so that you
22:24 see it. The purpose here is gonna take the fluid that is cerebral
22:29 fluid and we're gonna make it from blood. In other words, we're
22:32 take materials from the blood and we're talk about that in a moment and
22:35 after we've uh space it and so we borrow we were back to the
22:42 shortly thereafter. All right. And through these Arachnoid vili and ar granulation
22:48 gonna take place. Now, you have blood vessels, we said
22:53 is highly vascularized. So what we're see is we're gonna see blood vessels
22:57 are gonna be larger and they're gonna working through the arachnoid matter. And
23:02 what they do is they pass down the subarachnoid space and they get smaller
23:06 smaller and then that's when they pass into the PM matter so that they
23:10 then go into the nervous tissue. right. So it's highly vascularized.
23:15 ? Because I'm trying to send blood our normal circulation into the nervous
23:20 And this is one of the paths it has to take. Ok.
23:24 big vessels are becoming smaller in the location. All right. Last one
23:32 the dura mater. All right. now we're outward and so the dura
23:36 sits right up next to the All right. So it's a thicker
23:40 . Uh The way that you can about it is uh if you've ever
23:44 a Ziploc bag, like one of freezer bags, not one of the
23:49 in. But if you get one those thick uh freezer bags that is
23:53 thick of the der matter, and two layers to it, there are
23:58 two layers that are very closely adhered each other in most places. And
24:01 the layer that's nearest the bone is the osteo where the osseous and the
24:08 that's next to the men, the layer, right? So you have
24:14 dura and they're basically lying side by next to each other, except in
24:19 couple of places where those two layers apart and create this little tiny
24:25 And that little tiny space in between two layers is called a dural
24:31 And the dural sinus behaves like in . So blood leaving the heart will
24:39 in a dural sinus before leaving the c nervous system. Ok. So
24:47 , we haven't talked about veins, are how you deliver blood to a
24:51 . Veins are how blood leaves a . And so a sinus is a
24:56 pond for blood before it actually joins and becomes a vein specifically for the
25:04 . Ok? Now what? the sinus is important because this is
25:16 we're gonna get cerebrospinal fluid back into blood. If we took it from
25:21 blood, we gotta send it Ok? Those are the first major
25:28 we had bone and we these I'm gonna pause here. Are there
25:33 questions about? Yeah, it's not vascular. In other words, you're
25:42 gonna see like if you somebody can crack their skull over that dura is
25:49 blood vessels, but it's not gonna to the extent that you would see
25:53 the Arachnoid and in the P A in order to get in the
25:57 you have to pass through the So there are gonna be big blood
26:00 . But as I mentioned here, with the dural sinus that acts as
26:05 blood vessel. So you don't need have our veins because it is a
26:12 . It's behaving like that. We're to see we're going to large arteries
26:17 penetrate through these structures that are delivering to the different parts of the
26:23 All right, the simple way to about this is I'm just gonna work
26:27 way in. We have our then we have three layers of
26:32 We have the dura, the arachnoid that between the arachnoid and the last
26:36 . That's the pia we have that space and the sub space, what
26:40 have cerebrospinal fluid. All right. those are the way to think about
26:46 . Each one. How are they ? Why Arachnoid? Why is the
26:51 different than the pia? Right? the most closely adhered is the ps
26:56 like someone shrink wrapped it. The ones not so adhered, they're a
27:03 bit more uh spatial. All So what I wanna do is I
27:10 to move away from those physical structures I want to deal with that weird
27:15 structure, what we call cerebral spinal . All right. And what we're
27:20 at in this particular picture are this this this hollow structure that extends all
27:27 way up through the spinal cord and the brain. Now, I'm giving
27:32 this little bit of background. I'm gonna ask you the development of the
27:34 because it's, we're not a development . All right. But if you
27:40 at organism, all vertebrates, all . So, vertebrates include your
27:47 your sharks, right? Amphibians, , birds and mammals. And where
27:54 we on that list? Man? just want to make sure we all
27:58 , but we're all related to each because we're all vertebrates have a way
28:04 development where they start off as a . And when they start off as
28:08 tube, their nervous system starts off a structure. And in the central
28:14 structure is the hollow space that's filled fluid and then over development and whatnot
28:22 the proximal end or the most. uh it's what we call rostral.
28:28 they the front end of this what happened? It's a twist on
28:34 . And so the tube no longer like it looks like a bunch of
28:38 that have been bent. That's what is. It's just that, that
28:43 changed its shape because the the front changed its shape. And that's your
28:48 and brainstem instructors that are involved in , right? So when we looked
28:53 that picture of the spinal cord, could see the tube is a this
28:57 back to in a moment, but is just an, so the ventricles
29:03 the place where cerebral spinal fluid is . And so the ventricles space is
29:09 with cerebrospinal fluid and it's moved fluid through the ventricles and ultimately into that
29:17 space. All right. So the we talk about the ventricle is because
29:21 tells us where we're gonna get the spinal fluid. All right, there
29:26 four ventricles in the brain that you to know. Here's the good
29:32 They're very simple. All right. we start off. So this is
29:36 be the side view. This is be the anterior frontal view. We
29:40 off with the two lateral ventricles. have one on the left and you
29:44 one on your right. Everyone lift your right hand. So
29:49 yeah, it just see, it's if you don't know, remember this
29:53 L for left, right. So your right side, you got a
29:56 ventricle side, you have left a hard right and they're connected with
30:01 other. And the thing that connects is a hole that goes in between
30:07 . So we call it the interventricular Raymon. All right. Now,
30:14 weird when you look at these It kind of looks like they're these
30:18 paths. But the truth is is they're really not, they're basically all
30:22 kind of like a hole in the next to each other. So it
30:26 kind of opens up. And what do through this introvert vent for is
30:31 we open up from the lateral ventricles the, you know, difficultly named
30:36 ventricle, right? So we start with two, we're in third
30:41 so against third ventricle and the third looks like it's really, really big
30:46 the side. But you can see actually really just a thin tube that
30:49 and separates the two hemispheres of which we'll talk about. And you
30:56 actually see there's actually a point of in the middle of it, which
31:00 an important structure in the brain, we'll get to a little bit
31:03 And then from the third ventricle, we're doing is we're connecting to the
31:07 ventricle through a fancy named pathway called roll. I mean, doesn't that
31:13 fancy aqueduct? I mean, isn't what the Romans built? Yes,
31:19 big and they had arches and it's incredible amount of engineering, but we
31:23 them in our brain. So cerebral and then cool open up into that
31:33 space. See, we have these tiny openings, we have the uh
31:39 apertures. So that little point right and that little point right there is
31:42 to be the lateral apertures. And on the back side over here,
31:45 where we'd see the uh the uh aperture, all right, middle
31:51 I think it's middle median, maybe an aperture. And so here
31:57 actually going from this little tube and moving out from the middle of the
32:05 round there. So the would be lateral ventricles through the interventricular for into
32:15 third ventricle through the cerebral aqueduct to fourth ventricle out through the lateral or
32:21 median aperture into the subarachnoid space. the final path is down through that
32:28 canal that will then travel all the down through the spinal cord and go
32:32 the way down through the bottom and up into that subarachnoid space. So
32:37 have this flow and now flow is into the subarachnoid space and then from
32:42 subarachnoid space in these place and sub is gonna be back to the
32:48 which is gonna be through those little arachnoid villa and granulations through that.
32:57 and in matter and it's gonna open and into that dural sinus. And
33:02 where you push that cerebral spinal fluid mixes back with the blood. So
33:07 is kind of showing you that path movement. All right. So it's
33:12 going from here, the lateral to 3rd, 3rd to the fourth and
33:15 out. So you see the little showing, oh look, this is
33:17 go out and what I'm doing is now going out in that subarachnoid space
33:21 that subarachnoid space completely surrounds the structures out. It comes and around and
33:27 I'm going to join back up and leave via the dural sinus. So
33:35 is cerebrospinal fluid then? Now we where it's where it's being made.
33:38 is it? Well, it is , it's liquid. All right,
33:43 . It is mostly water. It material taken from the blood. So
33:48 plasma of the blood that has been through the ependymal cells. Now,
33:54 a couple of things that are important it. First off, it's
33:59 what it does in terms of protection ultimately, its function is to
34:03 provide environmental stability. And I think talk about each of these. All
34:08 sir. First off buoyancy, This is the cool part you need
34:16 have cerebral spinal fluid. So spinal fluid is not up against the
34:20 tissue in this little tiny case. right. So it surrounds the
34:25 If you didn't have this cerebrospinal the brain would then sit right on
34:31 cranium and it has mass and things have mass are going to lower themselves
34:37 much as possible, right? So about when you are lying on the
34:42 , your body kind of flattens itself , doesn't it? Right? Your
34:46 would want to do the same The difference is that the place that
34:49 flatten itself out is that big giant magnet and it would ooze its way
34:53 through that hole and you'd have a that's sitting in the vertebral column and
34:57 not helpful or useful. So what does is it actually serves as a
35:02 on which the brain is actually sitting it cushions the front of the
35:06 And the back of the brain, side of the brain, the top
35:08 the brain. And so I look it in terms of a characteristic,
35:13 would happen is if you removed all barriers between that, if you were
35:17 take a, put it into a of spinal, just set it on
35:21 , sit and float. But if took the brain and pushed your finger
35:25 it and sunk it down into the , it would sit wherever you sunk
35:28 because the brain has the same buoyancy the cerebrospinal fluid. So your brain
35:36 floats on top of the cerebrospinal fluid that's where it's placed right there.
35:42 when you shake your head is a because cerebrospinal fluid is mostly made of
35:48 , water is mostly uncompressed, That's what you find in breaks,
35:54 your shots in your car, so and so forth. And so when
35:57 move it into place, back and without hitting that hard bone, I
36:04 talked to you about this yet and is kind of where we're going.
36:08 Anyone here ever done any sort of dissection of rank like a cat or
36:14 , right? What kind of C A Yeah. So if you
36:19 done cat or something like that in the gross anatomy lab or,
36:23 know, you get it and what's deal that has been soaked in formalin
36:29 some other? Fix it right? , in plain English, you pickled
36:34 structures. Ok. And so if feel any of the structures inside that
36:40 that you're dissecting, they're hard. ? They're, they're there. You
36:45 , if you juice would come uh, like what you find in
36:50 body. All right. They're there that you can manipulate and see.
36:58 . I was fortunate as a grad to pull out brains of little tiny
37:05 , I needed the tissue. I trying to figure out how things
37:08 All right. And you think, , it's just like dissecting a organism
37:13 in an anatomy lab. Everything's going and hard. No brain is like
37:17 butter. All right. So if ever baked, you take the butter
37:22 of the refrigerator and you put it the counter and you let it soften
37:26 and if you pick up the butter hard, it just squeezes you hear
37:32 , right. It's all gross. is what brain is like. It
37:35 not something that you can just pull . So you can imagine right now
37:41 those pretty little skulls of yours is something that's hard. It's something that
37:46 incredibly malleable. And if you went this and there was nothing between your
37:53 and your brain tissue, your brain would flatten like a pancake kind of
38:00 or gross depending on how you wanna at it. Right? So that's
38:04 the cerebrospinal fluid is doing through its is is holding it in place and
38:10 you and wrapped around it, it's the shape of the structure, right
38:21 as protection. We talk, liquid cushion. Um, and you
38:29 , uh, things on the news concussions and stuff really. You're not
38:34 about a concussion when your brain smashes the front of your skull. All
38:38 , it's very hard to do that the first place. Not a
38:42 It's actually, uh more likely uh it's, it's damage caused by the
38:48 whipping around the inside water everywhere in body. Uh But one of the
38:55 that this does is like I it acts as shock. So and
39:01 not going to do this if I to run, you know, would
39:06 of be like, but my brain gonna go smash in the front of
39:12 uh cranial cav because that fluid is , it doesn't move. And so
39:17 brain kind of sits into place. takes a lot of, in terms
39:26 environmental stability is conceptually a little bit difficult to kind of wrap your mind
39:32 . All right. So material that brain needs in order to survive are
39:38 be moved through the blood to the , right? So you need
39:45 you need oxygen. Those things, cells need, that's how that stuff
39:48 delivered. But material doesn't go directly a cell. There's always thing in
39:55 blood and cell. We were learning in the first unit. Do you
39:57 what stuff is called? That's that fluid that surrounds the cell,
40:03 extracellular but plasma is also extracellular. , plasma plus interstitial fluid. All
40:11 . So the brain has its own . All right. The cerebrospinal fluid
40:18 not interstitial fluid. And remember it's its own compartment but it is in
40:24 apposition, it's next to it's only by that pia matter. And so
40:30 can move back and forth between the spinal fluid and the interstitial fluid.
40:37 this is important because if you slightly the bl the interstitial fluid, you
40:43 affect how neurons fire. And so having this cerebrospinal fluid which is in
40:49 and in flow, you can maintain internal environment of that interstitial fluid much
40:55 easily. You ready for a horrible , you wanna hear the horrible
41:01 OK. This will wake you All right now, you guys were
41:04 young when this happened. But you remember when the Wii came out,
41:08 know, it was a big So that was the year the PS
41:11 came out, the Xbox one came and everyone was going bananas and nuts
41:16 those two things were competing with each . And at Christmas time, it
41:19 like this is what everyone wants and Wii was released really quietly. No
41:23 knew about it coming out. And when it was released, all the
41:27 heads, which just went absolutely bananas bought everything was available. And so
41:31 wii was unavailable. I mean, sold out. It was like,
41:34 when I was a kid, it the cabbage patch kids. I
41:36 if you wanted it, just forget , you would not find it.
41:39 mean, there were adults fighting each in stores to get a hold of
41:42 stuff. There were lines and one the things that was going on is
41:46 there was radio stations giving away and in particular, this was occurred
41:50 southern California. So you've heard of types of contests, Mr Beast?
41:56 this all the time? Put your on the truck. Last person who
41:59 a truck gets to keep the You've seen that, right?
42:03 I know. You guys watch Mr . All right. My kids
42:07 I don't get it but whatever. right. So this was the type
42:10 contest. It was slightly different It was a p what, what
42:14 call it. I don't know if had a name for it, but
42:16 thought the P for the We And so what they did was they
42:19 a bunch of guests who are uh fight it out for this.
42:23 We Right? A $200 gaming right? And so they gave everyone
42:28 a certain amount of fluid. I know what it was like a gallon
42:31 water and everyone drank the water. it was the first person I had
42:33 go to the bath. I the last person who, who went
42:35 the bathroom got to keep the That was, that was the gist
42:38 the context. So it sounds pretty right now. Remember what I'm trying
42:43 describe here is showing you how important is to maintain that internal environment.
42:47 right. So one of the contestants a petite woman and they didn't like
42:53 everybody and say, OK, we're give you proportionally the same amount of
42:56 . They just gave her the same of fluid that say a 6 ft
42:58 would have. And after about 20 minutes, she fell over and
43:02 convulsing and then ultimately passed out and . Told you it was a terrible
43:08 right now. Why, why, did this happen? All right.
43:13 , she drank a gallon of water whatever the volume of, let's just
43:16 it a gallon because that's a lot water. You have about five liters
43:19 blood or, or fluid in your . That's blood. You have about
43:22 liters. I think you're about close about nine liters of total fluid in
43:25 body. All right. So what happened was you put the water
43:28 your body the first place it it goes to the digestive system and
43:31 digestive system, it goes down to bloodstream and, and it distributes out
43:34 the whole body that's the purpose of sort of distribution is to make everything
43:39 to everywhere. So that, that entire internal environment is the same.
43:44 right. But when you're adding pure to a system, you're adjusting the
43:49 salt balance. And so what she was too much water neutralized how much
43:55 and potassium she had. And we know how important that is in terms
43:58 action potentials. OK. So when brain got too much water in
44:04 the neurons couldn't fire properly. And the neurons that were responsible for her
44:08 rate and her breathing failed to fire . And so she basically drowned in
44:15 own bodily fluids right now. It that the water filled up her
44:19 it didn't fill up her heart, prevented the brain from firing. So
44:23 is an example of why it's so to maintain and is water dangerous.
44:28 is, yeah, it's clearly But I mean, but if you
44:31 about it like, oh look, a glass of water. No,
44:34 the, put the warning label on dihydroxy. Uh you know,
44:38 no, you don't do that. just it's water, right? But
44:41 can see the massive effect that a change can have on internal or physiological
44:50 . So having cerebral spinal fluid in helps to create an environment where it's
44:56 , oh, we have too much this, but we have an we
44:59 a compartment where we can move and things out before horrible things happen.
45:04 again, a gallon of water is lot of water, a lot of
45:08 very quickly, you know, because has to go someplace. All
45:15 Yeah. Ok. All right. this is a mechanism to remove materials
45:22 you don't want. So, chemical by bulk flow, bulk flow is
45:28 , we don't care what it just move it over here and we'll
45:31 things out. So CS F is in the ventricles and there's specific places
45:39 the ventricles where this is formed. you look at the little cartoons,
45:43 all the little red areas, all , those little red areas represent cood
45:49 . Cood plexus is an area in ventricles where the capillaries of the the
45:56 of blood vessels where exchange can take are, are gathered. So they're
46:01 up, they're very, very close the surface. And there are specific
46:06 called ependymal cells. They are a of glial cell that lie right next
46:11 the surface and they pull material out the blood. So it's water plus
46:15 chemicals out of the blood and they cerebrospinal fluid. And so you can
46:19 is it just in the lateral uh where you see the corro plexus?
46:26 . So it's in the lateral cord . It's in the third chid or
46:30 , third ventricle, lateral ventricles, ventricle, fourth ventricle. So all
46:35 vent or all four ventricles play a in creating cerebral spinal fluid. And
46:41 I'm making fluid. So here's the . And what's gonna happen is is
46:46 as I make fluid, it's gonna to an area of lower pressure.
46:49 that's why we get the flow as going on. Do we need to
46:52 this chart? Of course, not , but it's showing you this is
46:56 plasma is, this is cerebrospinal Does it look very different from each
47:01 ? Not really. I mean, wise, there's a slight difference
47:04 a slight difference there. And so is what they're trying to show you
47:07 like it's mostly plasma, but there's that have been removed or added to
47:12 plasma or concentrated in the plasma that it unique. All right. So
47:19 don't need to know the mechanism, know it comes through the up and
47:22 cells. Um There are other things can find its way into cerebrospinal
47:28 So anything that is fat soluble can its way into the uh cerebrospinal fluid
47:33 in the brain tissue. So for , if you're trying to invent drugs
47:37 work on the brain, you want to be fat-soluble because nothing's gonna stop
47:41 from getting into the brain. Um don't, that's not necessary. So
47:52 , the point being is that we're forming it through the ependymal
47:56 the material is being delivered via the . We're borrowing things from the
48:02 We make the cerebrospinal fluid and then , we return it back to the
48:06 . Now again, you don't need know this volume. This is just
48:09 thing. Um I'm just the Can you lift up your bottle real
48:13 ? Just lift it up high? it? No, I don't wanna
48:15 you, hold it. Do you know how much volume is in that
48:21 ? I heard 16 ounces. But we're scientists, so we have to
48:24 in mils. So how many 500 mils? Thank you very
48:29 All right. Now you can also on the side of the bottle.
48:32 says that's how I know. All . So that's 500 mils. You
48:35 put it down if you guys get sense there, it's 16 ounces.
48:38 mils. You make about 500 mils day. All right. So you're
48:45 that much cerebral spinal fluid per the amount of space you have in
48:51 subarachnoid space and in the ventricles comes to about 100 and 25 to 100
48:55 50 mils. OK. So you do the math right? 500 divided
49:01 1 25 four. All right, can, you can do that and
49:08 can do it's a nice simple number . So you replace your three a
49:14 times. So you're constantly making cerebral fluid, it's constantly pushing it out
49:20 a way and back to the So it's right. We're making it
49:23 way, it goes up and around out, it goes and it just
49:25 and you do this four times All right. But it's, it's
49:29 constant thing. It's not like, , let's fled the system. All
49:33 . So again, how is it ? It's reabsorbed because the subarachnoid space
49:38 through the dura through these granulations and vili and that fluid is being pushed
49:44 the pressure back out in, through , through that uh structure into the
49:49 , which is what that dark blue . That's venous blood. All
49:54 Now, there are a couple of things, ciliary, beating the ependymal
49:57 that are found on the coro are within the coro plexus have cilia and
50:01 purpose of cilia is to move things there and do that. And they're
50:05 saying I'm making the fluid you go way and the fluid goes that
50:09 Right? Second thing, postural factors you stand up, when you sit
50:13 , when you move everything like that pressure inside these structures and that helps
50:18 fluid. Have you guys noticed that you sit around, you kind of
50:21 your legs and you flex and stuff that? It's because your body is
50:26 a build up of pressure inside the vessels. And so what you're doing
50:29 you're actually contracting muscle to squeeze your vessels to push the blood forward.
50:33 would be a postural factor. Kinda . Huh. It's also what we
50:38 to as the skeletal muscle pump. right. So that's kind of the
50:42 thing you moving around, helps move spinal fluid. And lastly, there
50:46 a generic pressure just because I'm making , it's, it's where I'm being
50:52 , there's greater pressure there than when leaving. And so the difference between
50:55 two points is about 10 millimeters of . Um, heard of a spinal
51:01 . There's another name for it. an epidural, right? Have you
51:05 heard of those? All right. really cool. Well, I
51:08 maybe not to get, but to . All right. So what they
51:12 is they find T four and what doing is you're going between two vertebrae
51:15 you take this big long needle. what you do is you poke through
51:19 dura and then you go into the space. And how do you know
51:25 gotten into the right place? you inside the needle is a little
51:30 , um, crap. This is my brain just turned off. That's
51:37 spiders. Um, a catheter is word I'm looking for. I want
51:42 to pull out that catheter and if flows out, you made it
51:47 If fluid doesn't flow out, you it back in and you pull,
51:49 then you just keep trying to find get into that space. All
51:54 How do I, how does the come out. Well, there has
51:56 be a difference in pressure. So zero pressure outside, there's greater pressure
52:00 the inside. So I want to out fluid comes out, create a
52:03 tiny bubble. We got Twitter go start delivering drugs if it's an epidural
52:10 a pregnancy or for giving birth. right, that pressure is this right
52:15 , 10 millimeters of mercury. And that is a driving force from that
52:20 to that point through all of that . And so fluids are gonna move
52:25 because you have a high pressure and pressure. And I'm just gonna put
52:28 little asterisk here whenever you hear about pressure gradient or a chemical gradient or
52:34 remember high versus low, I'm always down to the low. This is
52:39 a big picture. So if the picture didn't help you, you can
52:42 a little bit more clearly. Fourth protection is the blood brain
52:53 All right. Now, with regard the blood brain barrier, what we're
52:57 with is something that is both physical physiological. So you can say anatomical
53:04 physiological. What this does is it the materials actually entering into that interstitial
53:16 surrounding the nervous uh cells, surrounding the neurons. And so what
53:21 doing is we're trying to regulate to horrible things from happening. Like the
53:25 for the wheat water is one of things you can't really regulate,
53:30 What about alcohol? Do you think can regulate alcohol? You can?
53:34 if you drink alcohol, you can how much alcohol actually gets into the
53:38 . So, if you drink like of whiskey, no, no.
53:42 you drink 1/5 of whiskey, you're be paying for it usually by going
53:45 the hospital and, and having your pumped if it doesn't kill you.
53:49 right. Try to avoid drinking full . That sounded weird. All
53:57 alcohol, water fats are physiologically capable passing fat barriers, right? So
54:09 other words, if the barriers created a cell, basically, you have
54:13 , that's in the way. And I can pass back and forth between
54:17 membranes very, very easily. But like ions, things like proteins,
54:23 like sugars, those have to be watery environments. So a membrane gets
54:30 the way and prevents movement. So we're dealing with here is a method
54:37 regulating what goes in and what comes of the nervous tissue. All
54:42 So, anatomical and physiological. All , anatomical. Why is it a
54:47 ? We're over over here. This a capillary. So here's capillary.
54:50 is where the blood is. So can imagine that this is where all
54:53 nutrients are. So this is where sugars are, this is where salts
54:56 , there's gonna be water and other . So things that your brain wants
55:00 things that your brain doesn't want can found in the plasma. All
55:04 So the the first thing that's gonna is that the astrocytes come along and
55:11 are a type of glial cell. what they do is they wrap themselves
55:14 the capillaries and capillaries are interesting All right. Now, generally speaking
55:20 your body, your capillaries are what refer to as being leaky. All
55:25 . So remember how we talked about junctions, tight junctions create a barrier
55:30 two structures. But in capillaries, tight junctions are not very tight,
55:34 leaky. An example of if you imagine that you have a, a
55:39 full of marbles and water. If reached in with both hands and scooped
55:44 the marbles, the water would probably out between your fingers, right?
55:49 big things are stuck inside capillaries just they'd be stuck inside your hand.
55:54 water and other small materials could actually between their fingers. So, with
56:01 to a capillary, they link between cells. All right. So small
56:05 are able to move back and forth the, the inside of a capillary
56:10 the outside of the capillary because of leaky tight junctions. When astrocytes come
56:16 , what they do is they tell capillaries, we don't like your leaky
56:20 . We want you to make your tight junctions tight. So it'd be
56:25 same think of the same situation, your hands in. But before you
56:28 your hands in, you put super your fingers. All right. So
56:32 when you go in, everything stays your hand, right? So nothing
56:38 leave the capillary. They're stuck inside capillary. All right, there is
56:44 leines. So that's number one, two, the astrocytes themselves wrap around
56:50 capillaries and they have tight junctions as . So now you have not only
56:55 epithelium, what we call endothelium, capillaries acting as a barrier, we're
57:00 to have a layer of astrocyte that as a barrier. So we have
57:04 two layers of cells to go through in between the astrocyte and the
57:08 What we have is we have a membrane, this is like a screen
57:12 . So if anything happens to leak way through, if it's too big
57:15 get through that layer of connective tissue that basement membrane, it's not gonna
57:20 through. So it gets trapped and . So we have a physical
57:25 And if I want to get something that, that means there has to
57:28 a carrier molecule located in the wall the capillary, there has to be
57:33 carrier located in the wall of the . And then there has to be
57:37 carrier on the other side of the . So if I want to get
57:42 , two my nervous tissue, I'm have to have that glucose carrier in
57:47 different spots just to get it into space. So that, that astrocyte
57:51 get fed. So you can imagine are lots of glucose carriers located in
57:59 tissue because that's the only way the gonna get food, right. So
58:05 other cells called pericyte, pericyte are uh cells. Um They're a type
58:11 mural cell. Uh basically, they to coordinate all the signals that's going
58:16 now, with regard to the All right, we've already kind of
58:21 about as I mentioned this, but just gonna reiterate it. If you
58:24 water soluble, you wanna stay where is. If you're fat soluble,
58:28 gonna pass through cell membranes just So a glucose molecule is a water
58:34 material. So when it's in the , it cannot pass the membrane.
58:39 anything that's water soluble needs to have carrier. If you're fat soluble,
58:45 don't want to be in the you're looking for any way to get
58:47 of the water. And so what is, is like, oh,
58:49 the way I can go. And you just pass on through. So
58:52 we're regulating here is simply those things are water soluble. So the brain
59:00 , or the astrocytes tell the capilla apes themselves determine what gets to come
59:06 and what gets to go out, is water soluble. So there's like
59:10 , it's like a, a list says, OK, we'll allow
59:13 this and this and so they put right carriers in the place or the
59:16 channels in the place and that's how moves in or out of the
59:22 But there are some things that are soluble like alcohol. So, if
59:25 go drink alcohol, does it affect brain? Oh, yeah. You
59:30 , I say that with a smile my face because fun just don't
59:34 don't drink too much, drink good , not bad, good stuff.
59:39 right. Yeah. But what's good ? We're not gonna talk about that
59:43 now. Yeah. It takes years years of practice and experience to figure
59:49 stuff out and you must wait till 21 unless the state says it's
59:54 So I, when I went to that was the year they changed all
59:58 drinking ages as 21. I was , really? But I went to
60:01 in New Orleans. Do they No. All right. I think
60:08 care now. But back then they not care. All right.
60:14 So where do we see this blood barrier? Well, it's gonna surround
60:19 cerebral blood vessels. All right. we're uh basically creating that barrier to
60:25 things going in and going out at , at the coid plexus. We're
60:31 see it there as well, but in the same extent that we see
60:35 everywhere else. And the reason being because we need to pull things from
60:39 blood. Right. So we have different type. It's, it's regulating
60:45 and then there are some parts of , uh, the brain that doesn't
60:49 a blood brain barrier at all. right, we call these the
60:53 uh, ventricular organs. So, around the ventricles. All right.
60:58 , where are some of the places we don't have all this stuff?
61:01 , the first is gonna be the , hypothalamus is the master endocrine
61:07 It's a master gland is what we it. And basically what it does
61:11 it needs to know what's going on your body. So it could tell
61:14 body what to do through the signaling . In other words, through different
61:18 . So it needs to be able be able to access the blood very
61:23 . Pineal gland is gonna output Anything that's pretty much output hormones.
61:28 right, Coro Plexus needs to have permeability as we mentioned. And this
61:32 the fun one, the vomiting All right. What is the most
61:36 way for you to get a toxin your body? Say again,
61:43 Yeah. Ok. So how are gonna get that poison in your
61:46 What's the most likely way for you do that ingest it? Right?
61:50 mean, do you guys live by five second rule? I think we've
61:54 about this before you drop a It hits the ground, it rolls
61:57 spider webs and stuff and you just , wipe it off and you're
62:00 hm, I'll eat it anyway. you're looking at me like I know
62:04 goes through spider webs. That, , that's, uh, it's an
62:08 . I'm, I'm eating that Ok. The most likely way for
62:14 to put something bad in your body not to be bitten by something or
62:19 be injected in you. It's to it. Right. That is the
62:24 likely way. So, if toxins circulating in your body, the vomiting
62:28 goes, oh, look, here's toxin. Oh How did this get
62:32 ? Well, you probably ate You idiot. I'm gonna throw it
62:35 because if it's in the blood it's still in the stomach and that's how
62:38 doing it. Here's a fun If you get by rattles, get
62:41 by a rattlesnake. What are you do? What's one of the
62:45 I mean, your arm is gonna swelling up. But what do you
62:47 ? You feel nauseous? And you ? Why? Because the brain
62:51 oh, you probably ate something stupid that's why you throw up,
62:57 Notice, get a concussion. I feel good. Bad things are
63:01 What do I do? Throw The odds are the bad thing that
63:05 would not be bashing my head against wall. It was probably because I
63:08 something stupid because cookie rolling across the is on my list of OKS.
63:13 right. Y you again, you think. Not 21st century. You
63:17 think way back in the dawn of , here's a bush. Look,
63:22 berries on it. I wonder what berries do. It looks like food
63:28 like food, tastes like food makes feel funny. All right. There
63:34 go. That's pretty much man's entire . Putting weird things in our mouth
63:39 throwing up, coming down to the . All right. So this is
63:48 trying to show you what this blood barrier looks like. All right.
63:52 we move things. So there's what refer to as lipid mediated transport.
63:56 what is lipid mediated means I can through a membrane, no sweat,
64:00 I can just go right on through would be lipid right there. You
64:05 . So if you have a soluble soluble molecule, it's gonna pass
64:10 freely through that membrane. So these just some examples, oxygen is something
64:15 cannot stop where oxygen is gonna It just goes wherever it wants to
64:18 . Same thing with carbon dioxide, steroids. These are again molecules that
64:23 lipid soluble. They're, they're a of lipid. There are some lipophilic
64:28 . And so when you start learning different drugs, as you move on
64:32 your further careers, you're gonna learn certain drugs that are available for treating
64:37 brain. And it's like, oh is the characteristic? Well, it
64:39 lipid soluble lipophilic, there's carrier Now here what we're dealing with are
64:48 molecules. So like glucose amino nucleotides. And so here what you
64:53 is you pass it from one side the cell, move it through the
64:55 side of the cell and off you . All right. So that would
64:58 carrier mediated. But bigger things carriers work. So you're gonna have to
65:03 receptor media to transport. So here gonna have to have the right
65:07 So you can see now where the comes from. If I don't have
65:10 right carrier, it's not coming If I don't have the right
65:14 it's not being moved across. So need those things. So,
65:18 growth factors, these are things that need, these are much larger,
65:22 proteins or peptides, they need a . So you're gonna use vesicular transport
65:28 do that. All right. So idea here is different molecules use different
65:35 and the blood brain barrier determines what to come across that membrane. So
65:40 a protective barrier. All right, getting down to the end. Doesn't
65:50 feel nice? And when I say and I have three slides left,
65:54 know, I just screwed it It's gonna be 40 minutes of me
65:57 about something. I'm not gonna, gonna just try to finish it off
66:02 . All right. So this is be our first deep dive into the
66:09 of the brain. And what we do is we want to just look
66:11 how great or the blood is delivered the brain. That's what this little
66:16 is trying to show you here. it looks very scary because there's a
66:19 bunch of things that have been labeled and remember, you don't need to
66:22 everything here. It's just the things I've kind of highlighted and what I
66:26 to show you here is that if look at the brain, you can
66:28 it in half. So there's an portion and a posterior portion. And
66:32 if you can divide the brain in way, that helps you kind of
66:35 out what goes on what side? right. Now, one of the
66:39 that is interesting about the brain is there is a structure that has developed
66:44 in everybody. I'm gonna say this because we're go, we talked like
66:48 is like everybody has a circle of and it's not true. It's about
66:51 of the population has a circle of . All right. And what this
66:55 is a pathway that allows us to the front and the back together.
67:01 basically, it's a circle of So if one gets clogged blood flow
67:06 occluded, blood can reach both halves the brain. It's kind of
67:09 but not everybody has that, but pretend like it is true. All
67:15 . So with regard to the anterior , what do we have? All
67:19 , you guys have grown up learning you have an artery in your
67:22 Do you remember what that artery in neck is called carotid? Right?
67:26 that's the one when you go to a slasher movie and they cut the
67:29 and the blood goes squirting out and the person kills over dead. That's
67:32 carotid artery. All right. So carotid arteries are delivering blood up to
67:37 brain. So you have to imagine , this is a two dimensional picture
67:40 to to trying to show you three . And so here's the carotid artery
67:45 what it's doing is it's going So it's going into the screen and
67:51 is going to divide into a whole of different arteries. All right,
67:55 arteries that we're interested in is the cerebral and the middle cerebral. Without
68:00 showing you the picture, where do think the anterior is going to the
68:04 of the brain? What do you the middle cerebral artery is going to
68:07 the middle of the brain? So that big artery going up to
68:12 blood to your brain is going to into a couple of branches. The
68:16 branches we're most interested in is the cerebral and the middle cerebral. In
68:22 little cartoon. Here it is, the anterior cerebral and uh I think
68:27 actually, yeah, I was gonna they mislabeled this there, this is
68:30 anterior cerebral. Here's the middle cerebral off in both directions, the thing
68:35 between them, this is the communicating there. All right. So if
68:39 look at the posterior segment, so you can see the line. So
68:42 is the posterior side. We have arteries. If you had to guess
68:47 vertebral arteries were located, where would have to say that they're located near
68:51 vertebrae? All right. So that's you have here. So you can
68:54 here, here's the vertebral arteries, a pair of them, they're going
68:57 together and they're supplying the brain which is coming out. So you
69:03 see here's the brain stem, it's turn into the spinal cord, it's
69:06 side by side of the brain stem then it has a couple of divisions
69:10 we're interested in. All right, come together and they form the basilar
69:16 . Now, where do you think Basar artery is located relative to the
69:21 ? The basal side, the That would be the best answer.
69:26 this is the basal or artery and what's coming in and joining up to
69:29 circle of Willis. So two vertebral join together form the basal artery.
69:38 , in our little cartoon here we the little tiny spider legs. See
69:41 little tiny spider legs, right? are called the ponte arteries. The
69:47 arteries are next to a structure in brain called the ponds. Do you
69:53 how arteries are named? They're named where they go. All right,
69:57 call them the named arteries because they you exactly what they are.
70:02 the ponte arteries is feeding the ponds that's what the big giant bump is
70:06 you're looking at. All right. have the anterior inferior, what a
70:11 name. But without anything, if see anterior inferior, what are you
70:16 ? Front and below? So the and below cerebellar arteries and so it's
70:24 you the structure, it's gonna be or not inner vascularized in the front
70:28 the bottom of the cerebellum. And then the other one is the
70:34 cerebellar artery. Now, here they're you here's the posterior, inferior,
70:39 inferior, there's paired and then over , the one that's wrapping around the
70:44 of this larger structure, that's this structure is the cerebellum. So that's
70:49 this is. That's the posterior cerebellar . Now, blood is gonna come
70:56 out. We're not doing all the of the brain. We said that
70:59 are dural sinuses and there's a bunch them, but they all converge and
71:03 form your jugular vein. And so jugular is the other one. You
71:10 , when you're playing a, I remember the name. Now. Um
71:16 Combat Street Fighter, what do they ? Go for the jugular? All
71:23 , rip that bad boy out. carotid arteries, jugular vein. So
71:31 we didn't name everything in here. don't want you to know everything in
71:34 . I want you to know the ones and this is kind of a
71:37 way to kind of see what we're with here. I didn't even
71:41 did I name Posterior Cerebral up Oh, I did, but I
71:44 highlight it. So I thought I'd it. So here's the posterior cerebral
71:49 right there. That's the big one uh uh anterior to the superior
71:57 All right. But this is a way to kind of look at
72:00 Just thinking of how do I get to the brain itself? Well,
72:03 had the anterior cerebral, I had middle cerebral and I had the posterior
72:09 . So basically, there's three and named exactly to where they go the
72:14 , the middle and the back. that? OK. Yeah. So
72:21 , coming back, why do we about the circle of Willis?
72:24 this ensures that blood goes both All right. If I clog one
72:30 up, I have a communicating artery allows the left and the right hemisphere
72:34 receive blood. I don't just basically the flow of blood and we're
72:39 All right. It's just a, uh a mutation that has occurred that
72:43 been advantageous to keeping us alive. so that's why that why it still
72:50 . All right, I've already mentioned basilar artery. Basically, it forms
72:56 the vertebral artery and the spinal last little slides and we're done and I
73:02 this here because while we just had time, it could have gone to
73:05 next class. But what I wanna is we're gonna be dealing with two
73:08 of cells. We're dealing with the system. The first is gonna be
73:12 neuron. We've already talked about the . These are excitable cells,
73:16 Their job is to transmit electrical signals we start class. Um On Tuesday
73:21 , we're gonna talk about the supporting . But what I want to show
73:25 here is we've already learned about this . All right. And we spent
73:29 of our time thinking about the but in the nervous system where the
73:35 is replaced by, primarily by the neuron. But just because it looks
73:41 and is named differently, it doesn't that it behaves differently. We still
73:44 receiving sides, we still have a side, we still process and send
73:49 through neurotransmitters, greater potentials and action . All right, structurally, it's
73:55 a pyramidal cell because like a there you go. What we're going
74:04 see here is that they're found all the place and it plays an important
74:09 in cognition. What is cognition, and thinking. So that's where we're
74:16 to leave off. We got done today, didn't we? We
74:22 All right. So I will see on Tuesday. We got a big
74:24 show up, wear red, scream yell. There's a reason to play
74:31 game. Yeah. You
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