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BIOL 2301 Human Anatomy & Physiology I - 2103_lecture16_0324
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00:04 Alright, y'all. So here we , one more time today is the
00:09 we transitioned from muscle into the nervous . Alright. And everything we're gonna
00:16 now until the end of the Its nervous system. I know it's
00:24 of a pain in the butt, are a little high. He would
00:31 if that helps. Um And so that means is, is that what
00:35 doing is we're gonna kind of do this overview flight of structure and we're
00:41 be dealing with a lot of functionality I'm just gonna promise you they're gonna
00:45 place places where it's like, this is easy mode and then they're
00:48 be places where it's like, what hell are you talking about?
00:51 that's, that's just the nature of nervous system, nervous system in my
00:55 , is one of the most complex . Not surprising given that it governs
00:59 your body works in general, It's the control center of your
01:05 But also because there are lots of and I'm just gonna put this up
01:10 , just so that we're aware of . Like you're gonna, we're gonna
01:14 about systems to go, look, isn't in charge of movement and this
01:18 is in charge of movement and this is in charge of movement, you're
01:21 to be like, well, which is in charge, They're all in
01:23 together. And so we just kind have to, you know, kind
01:27 learn the definition and kind of and it to the to the structure.
01:33 . I say it's hard and I'm doing that to scare you. I
01:36 students who are like the easiest stuff ever done, I like this
01:39 It's much easier than this stuff, your mileage may vary. All
01:43 but what we're gonna do today I is some of the simpler stuff.
01:47 we're gonna do is we're gonna look um really just how the brain is
01:52 by the central nervous system is protected the surrounding environs of your body.
01:58 then the very end, we're going get deep into the anatomy, we're
02:01 to name some of the arteries of brain. And so when you're dealing
02:05 nomenclature and naming and identifying this, just flat out memorization, the other
02:10 is more conceptualized and so our starting here really is just saying,
02:14 how do we organize the nervous Alright, and there's really just two
02:20 of the nervous system and you're gonna things broken down a little bit
02:22 where we're talking about autonomic nervous system then part of the autonomic nervous system
02:26 they kind of go between these two that we're seeing up here, which
02:30 the central nervous nervous system and the nervous system. Alright, so there's
02:35 two principal parts and it's really, , really easy to identify the two
02:40 . Alright. Central nervous system is brain and your spinal cord, the
02:44 . Alright. And then anything outside is peripheral nervous system. Now.
02:49 what we say is the peripheral nervous consists of the nerves in the gangly
02:53 this is a really key point. star. Put this in your
02:56 Alright, nerves are only found in peripheral nervous system. Okay, that's
03:04 be one of those questions I asked the exam that someone's gonna get and
03:08 gonna be going, oh yeah, learn about this stuff. Nerves,
03:11 system, they go in the no nerves are external to the central
03:15 system. Central nervous system is solely brain and the spinal cord. All
03:20 , so it's a real simple All right. The central nervous system
03:25 responsible for integrating information and sending information coming up with solutions to information and
03:32 what we call a control center, problems that the body's experiencing. All
03:38 , well, what are problems or are things that is doing?
03:41 the peripheral nervous system is in charge sending information to the central nervous system
03:46 then receiving and doing or issuing the of the central nervous system. So
03:51 kind of see what we have here we have a way in, we
03:54 a place where we process and then go back out a different way using
03:59 peripheral nervous system. So peripheral nervous is going to and from the central
04:04 system and so the brain does the and the spinal cord does the processing
04:12 we'll see a little bit later. , so that's gonna be our two
04:16 and there's some very basic they want do that. Alright. Some basic
04:22 principles. Alright. First off, a hierarchy of organization. What that
04:26 is that there are lower levels. going to relay messages to and from
04:30 upper levels. Alright. So, example, information is more complex and
04:36 processed up in the cerebrum what you of as your brain than it is
04:42 in, say, the spinal So information comes in. There may
04:46 a level of processing that takes place the spinal cord, but if it
04:49 requires complex processing, it always goes to the higher order areas of the
04:56 . All right, So there's this of organization. Now, there's a
05:00 you can think about this. That sense to biologists, but maybe not
05:03 who haven't taken a lot of You can think of simple organisms,
05:06 know, simple, simple things like and fish are less complex than,
05:10 , amphibians are. Amphibians are a bit more complex and fish, but
05:14 quite as much as reptiles and so and so on and so on.
05:17 really what you're looking at here is can see parts of their brains get
05:21 and more complex as you move up animal or evolutionary hierarchy of of
05:29 All right. And so we're kind at the pinnacle of that. So
05:32 always think of ourselves as the best the smartest and the brightest and stuff
05:36 not necessarily true, but in terms organizing our sides and stuff are pretty
05:41 organized and it's a result of the that our brains work. All
05:45 secondly, there are structural and functional of organizations. Now this seems like
05:52 obvious statement. Basically what it says neurons with similar functions are gonna hang
05:55 with the neurons of similar functions. , you look at an area that's
05:59 processing how vision works. They're not be like, oh, here's vision
06:04 here and I'm going to send information to the front frontal lobe to do
06:08 . All the vision stuff starts off here and then it slowly works its
06:12 forward. It's not just mishmash. there's a high degree of organization to
06:16 brain. So once you learn the of the nervous system, everything kind
06:21 falls into place and over the course the next this unit and the next
06:26 , we're gonna look at that It is topographical meaning that the neurons
06:33 organized in such a way that they the body. This is gonna be
06:37 cool when you see this at least think it's really cool and I'm just
06:39 use the sensory section of the brain a second. So, if you
06:43 at the sensory region, in other , the things that I touch and
06:47 the areas that are organized. If map it out, match the
06:52 there's your head and then there's your organized along the length of the
06:58 So you can actually look at and , oh if I stimulate say,
07:02 I don't know my toe, I'm specifically stimulate a portion of my sensory
07:07 or the sensory location in the brain around here. But if I stimulate
07:10 fingers there's gonna be some place up . It maps like like you can
07:16 stick figure, try to picture people looking at me like you're crazy.
07:21 about this? You guys No, piano. You know the keys you
07:25 high notes on one end, low on together end. Yeah. The
07:28 of the brain that's responsible for understanding pitches of sound are organized just like
07:36 because that's how your ear is And so there's this organization. That
07:41 sense because it matches how the body organized. The other thing and it
07:51 of looks weird when you see the up their plastic, the central nervous
07:55 itself is plastic. And what does mean? It means it's malleable,
07:59 changes, it's not static. So would be something that changes static to
08:05 that doesn't change. All right. in the process of learning information and
08:12 stuff, your brain modifies itself and interactions between cells in order to strengthen
08:20 or weaken connections between those cells to that whatever pattern that your brain is
08:27 is preserved. All right now, don't want to go way off the
08:34 with this. But the idea here part of learning is a series of
08:40 firing. So basically it's a pattern neurons firing in a specific sequence.
08:45 when you experience something your brain it's like oh I'm watching oh I
08:49 know. Let's say, I'm just try to do something that's simple.
08:53 say you're learning how to dribble a right? And so you bounce the
08:58 the first time and if you're like kids, you bounce it like two
09:00 three times and it rolls over off the side, you will pick up
09:03 you bounce it a couple more times eventually what you're gonna do is you're
09:06 to learn how to bounce the ball you've generated a pattern of how the
09:11 fire. And so your brain basically out the neurons that it doesn't need
09:15 that pattern and it coalesced or makes stronger connections between those neurons. And
09:21 can actually see the pattern generated if are able to put probes in there
09:26 watch it and that's how you remember to dribble a basketball. You don't
09:31 have to think about it. Your just has that pattern. So when
09:34 get that basketball you start dribbling, just does there was a movie a
09:38 of years ago, you guys are too young now to know that it's
09:42 there. It was jim Carey and was, I never get the name
09:44 the movie right? Something of the Mind. Sunshine. Spotless Mind,
09:48 know this one? Okay. The of the movie is jim Carey and
09:52 think it's kate winslet. Um we're , they broke up, it was
09:56 horrible breakup and they bow and she to forget the relationship that it ever
10:02 . And so in this fictional world can actually erase memories. And so
10:07 idea is that they're going through and the memory and the memory is trying
10:11 escape being erased and it's all the things that they've done in their
10:16 And the premise here is that memories stored in neurons. That's not how
10:19 works, memories are patterns of neurons . So when you think of
10:25 I'm just gonna think of your 1st crush, got a picture of that
10:31 in your head. First crush, , sad, whatever it is,
10:36 was because you generated a pattern that been stored in perpetuity in your brain
10:45 your brains are plastic. Okay, the first level of organization that we
10:56 to understand in the central nervous system that the brain is divided into two
11:02 areas we have what is called gray and what is called white matter.
11:07 . And this principle is gonna be of just universal when we deal with
11:11 central nervous system, Gray matter is not gray. It's just beige
11:18 but it's relative to the lighter So you can see it here.
11:22 gray matter. This is this is cerebrum. This right here is a
11:27 slice through the cerebellum and through the stem. This is further down in
11:31 brain stem. This is down the cord. Alright. So those were
11:34 doing different cuts and they're showing you the cuts are. There's one there's
11:38 . There's three. There's four. right. You don't even know where
11:40 are. But I'm just trying to you where the gray is.
11:43 the gray matter you can see here the cerebrum is on the outside and
11:47 there's spots on the inside. When get down to the spinal cord you
11:50 see there's only gray matter on the with kind of this butterfly pattern.
11:55 gray matter represents and what it is are the cell bodies of neurons.
12:02 . So these can be motor neurons on where you are or they can
12:06 what are called inter neurons, which get to a little bit later.
12:09 the idea here is when you think that neuron remember we have the neuron
12:13 the cell body with a bunch of hanging off and then we have these
12:16 coming away and off of them. gray matter represents clusters of where those
12:22 bodies are located. And so where cell bodies are. This is where
12:27 is more or less being processed. remember each individual neuron is not doing
12:31 . It's within these large networks. so you're sending signals from one cell
12:36 the next. And so if you're with inter neurons, these cells that
12:39 have really long axons. So clustered makes sense that they're there and they're
12:44 that pattern that we're generating. Alright there'll be capillary beds because you have
12:48 you have cell you're gonna have to a capillary beds. There'll be
12:51 there might even be some small and um my eliminated axons in these
12:57 All right. But generally speaking, you see gray matter, you need
13:01 think cell bodies information is being Okay. It doesn't matter if you're
13:07 here, it doesn't matter if you're here or in between any of those
13:10 . All right. Now, when see these clusters, like for
13:14 right here, right. Or those areas right there. 123123. Those
13:21 called nuclei. Alright. When they're on the outside, they're referred to
13:26 the cortex. So there's terminology we just generally in anatomy. If it's
13:32 , there's kind of it's called the or the middle. So medulla cortex
13:37 the edge. So this gray matter is cortex the gray matter centrally located
13:43 here. Those are called nuclei The dark areas. These are referred
13:49 as nuclei. All right now. matter on the other hand is primarily
13:56 axons. So white matter represents is the the pathways through which signals are
14:03 from one part of the brain to other. So for example, I'm
14:07 going to say say I want to information on this cortex of that
14:10 I need to send a fiber across that. So you can think of
14:14 white as being wires is lack of better term. Those are the
14:20 So wherever you see white matter and can see it all over the
14:24 These are where the axons are And the reason it's white is because
14:30 my eliminated, my elimination is primarily . Right? I mean it's foster
14:36 from those cells that have been squished so that gives off this wide
14:41 All right. So, they're gonna connecting different parts of the brain and
14:46 going to deal with this in much detail. Alright. Or different parts
14:52 the central nervous system. So, here in the spinal cord, I'm
14:56 information up and down. And so white matter represents the pathway is going
15:00 and down the spinal cord. so We have gray matter. Gray
15:07 cell bodies information is being processed. matter are myelin axons. Myelin axons
15:13 how we're sending information between two points far. So good. Yeah
15:22 We will get to that a little later. I don't want I don't
15:25 to go too far here because I to focus in on the on the
15:31 how we protect the brain. We nuclear is just a term that says
15:37 have a whole bunch of the cell clustered together. All right now we're
15:41 to use a different term. So is in the central nervous system.
15:44 central nervous system, it's called We're going to see gray matter in
15:48 peripheral nervous system. Were just not with it right now and we have
15:50 different name for it. We call the ganglia. Right? And if
15:53 went back to slide where maybe to . So yeah, nerves and there's
15:59 . Alright, So there's gray matter exists out there in the peripheral nervous
16:03 . We're just not getting to it . So right now, the definition
16:06 want you to take in is gray equals processing clusters of cell bodies.
16:13 matter equals axons Transmission between two Take those two definitions with you right
16:19 . Everything else is going to make as we move forward. Now,
16:30 here? Well, no, this spring. So no one's taking the
16:33 . You're gonna go and you're gonna a lab and you're gonna get to
16:35 into an organism, Probably cat. you'll get to poke at the brain
16:40 little bit, you know, and everything that you poke at in a
16:44 in the lab is usually an animal has been preserved for some period of
16:48 when you go off to your professional that they have a gross anatomy
16:53 that organism is going to be a and you're gonna get to poke
16:56 stuff that has been preserved for quite while, stuff that isn't preserved.
17:00 we say preserved, it's like it's like if you take a cucumber
17:03 drop it into um vinegar, it it. And so what we're doing
17:07 to to these organisms, we're putting into some sort of fluid. Um
17:12 it's formal in which is nothing you to worry about. But basically it
17:17 it and hardens the tissue and then can play with it and stuff.
17:21 you look at brain tissue, it's easy to slice because it's been hardened
17:24 it's like you can cut it and see the sections and stuff like that
17:29 real life before you've done all this . Brain tissue, it's kind of
17:35 warm butter. Alright. It basically held in position and shape by a
17:43 of different structures. And if you to take your finger and push it
17:46 it, it would literally just is that a good sound effect,
17:52 ? I mean I'm not talking to that you take out of the refrigerator
17:55 press against and it takes effort. talking butter that you've left out for
17:59 all day long and you put your on it and it would just sink
18:02 into it. It is really, soft. It is not being held
18:06 very, very well. It's gross disgusting like most things in the
18:12 All right. It's still fun. how my hands have just got all
18:17 . All right. Now, if can picture this soft structure and if
18:23 picture your life, do you have rough life? Yeah, I
18:27 ever knocked heads with somebody? I really knocked heads come up to
18:32 knocked him. Yeah, okay. guys are like, yeah, of
18:35 . You know, you're taking me all the time just right there.
18:39 right. So you want to protect structure and so what we wanna do
18:45 we want to look at the four that actually protected one structure we've already
18:50 about, right. What's the first that when you think of protection of
18:53 brain? What do you think about skull? Skin would be a nice
18:57 because it's right out there. But the skull. Right? That's my
19:00 helmet. Right. This allows me walk into walls into butt heads with
19:06 , right? And do stupid Anyone ever leaned over picked up something
19:10 a lower cabinet, forgot to close drawer and just like walking around like
19:16 can't believe I did that. So that mushy substance that you call the
19:22 center of your body is first off by bone. And this is
19:27 Also for the spinal cord we talked the vertebrae we talked about we got
19:31 body of the vertebrae and then we that ring of bone that created that
19:37 that vertebral canal through which the spinal travels through and it's flexible so that
19:44 flexible but it also protects. So first layer is always going to be
19:49 . Alright so the cranium of the that's easy mode. That's the first
19:53 of protection. Nice hard. Now you have this hard substance pressed up
19:59 the soft butter like substance you need have something that hopefully hopefully prevents the
20:03 like substance from actually mashing up against and losing its shape. And so
20:07 is where the two other major layers from the third layer. The final
20:13 is going to be this blood brain which is more it's it is a
20:16 barrier but it's also a physiological So there's kind of this distinction
20:21 So what I want to do first focus on these two middle ones and
20:24 towards the end we're going to talk the blood brain barrier. We have
20:28 layers of tissue that lie between the and the brain tissue. Alright these
20:37 called the meninges singular form of meninges mini M. E. N.
20:42 . N. X. Alright so singular meninges we're just gonna calm the
20:49 . And what they do is they between the bonus tissue and that nervous
20:54 . And there's gonna be some fluid there as well. Which is what
20:57 going to get to here. Which the cerebral spinal fluid. Now the
21:04 spinal fluid is fluid that also serves a barrier. Water is not particularly
21:11 fluid is not completely. I mean particular, cerebral spinal fluid is primarily
21:16 with with stuff in it. And if you have fluid, what you've
21:21 is you've created a malleable layer that compress and doesn't shift all that
21:27 And so it serves as another barrier protection. But it also serves as
21:32 cushioning layer. We're gonna look at a little bit more in depth.
21:37 last layer the blood brain barrier is barrier between the blood vessels and the
21:44 the brain tissue. All right, you have materials that are flowing in
21:49 blood. There's things that the brain from the blood but it doesn't want
21:53 from the blood. It wants to what it's going to get and what
21:57 not going to get and throughout the of your body wherever you have this
22:03 of exchange what are called capillaries. is no barriers. So basically all
22:08 of things can flow into your tissues all sorts of things can flow out
22:11 your tissues. And so what we've here in the brain is we've created
22:15 selective barrier between the sites of between capillaries, which normally would do this
22:22 exchange and this tissue. So it this physical barrier as well as a
22:29 barrier. Two. Whatever is in blood. All right now, let
22:34 give you an example of why this important. Alright, Your immune system
22:40 take care of most of the pathogens get into your body, right?
22:43 is why you have the five second . That's why you can like door
22:46 . There's all sorts of reasons immune immune system is incredibly powerful in terms
22:52 what it can do with the outside . Alright. But what we don't
22:57 is we don't want something that can a little bit of harm to get
23:01 our brains because it's our control And so if we allow pathogens to
23:06 their way into the brain, then immune system would come in and the
23:10 response of the immune system which we'll to learn all about A. And
23:12 . Two is that it causes inflammation when you start getting inflammation and control
23:18 , you're going to cause all sorts havoc and problems. So what we've
23:21 is we've basically created a seal between tissue and the rest of the
23:26 including the immune system. So that be what we've done or that's that's
23:33 of the purpose of the blood brain to make sure that we have this
23:36 seal or this environment that's protected away not only pathogens, but also the
23:43 system. So, what we're gonna is we're gonna just dive deep and
23:48 gonna go through the meninges. We're talk about the cerebral spinal fluid,
23:51 we're gonna talk about the blood brain . And then we're going to talk
23:54 about certain arteries, you know, terms of their names. And then
23:58 think that's the lecture for today. , to manage thingies, as I
24:04 , singular minx, there's a way you can memorize these. You can
24:10 from outside in inside out. I'm go inside out because it creates a
24:16 just a quick pneumonic, right? creates a pad. So, that
24:20 of makes sense. But really the way to explain it is to go
24:23 the outside in. So, but we go from the inside, we
24:26 the P. M. Matter right . That little brown line, we
24:31 the arachnoid matter, which is this light purple ladies, you might have
24:38 help me with that name. maybe lavender. Okay. And then
24:43 have the darker purple. I'm just to call it violet. It's not
24:47 violent, but Sure. Why I'm a guy. I know like
24:51 names like eight colors. All So, that would be dura
24:56 All right. So, you can it goes dura arachnoid pia from outside
25:00 . But if you do the other inside out, it creates a
25:04 That's kind of easy to remember the . All right. So, we're
25:09 start with the P. A. I said, we're going the wrong
25:12 . The PM matter is highly highly arised. And what that means is
25:16 that point where the blood vessels are start entering into the nervous tissue.
25:22 . So, you can think of like you have your brain and think
25:26 taking a piece of thin plastic and wrapping it around the brain. That's
25:30 the PM Matter does. It covers contour. It goes down deep into
25:35 uh sulk I Which are basically the right? And it just closely moves
25:41 and as a result, any blood that wants to penetrate into the blank
25:46 is first going to be associated with P. A matter, and then
25:50 going to pass underneath and it's going travel into the tissue. It's at
25:54 smallest levels. In other words, are the very, very small arteries
25:57 are ultimately going to become capillaries. right. The layer over it is
26:04 arachnoid matter. That's that light Alright. Again, it's also richly
26:09 arised, meaning that it has lots blood vessels. Alright, So,
26:12 got lots of blood vessels in the . I got lots of blood vessels
26:16 the P. M. Matter. blood vessels. The arachnoid matter gets
26:19 and that's when they moved down to P. M. Matter. All
26:23 now, there's an area that sits between the two. You say?
26:28 put my hand down here. Here's . Here's arachnoid. So there's a
26:31 that space is called the sub arachnoid . It sits below the arachnoid
26:36 And if you look at this picture , you're gonna see that it has
26:39 whole bunch of these little tiny And these lines are basically small connective
26:44 structures called Tropically. And the Tropically holds the arachnoid matter in place against
26:51 pia. With that space in between then that space is filled with cerebral
26:56 fluid. Now, when you hear word arachnoid, what do you think
27:00 spiders? Alright. And the reason called the arachnoid matter is because of
27:04 ridiculously it looks like there's spider webs there. All right now. I
27:09 to think about this is where the spiders live. Have you had brain
27:15 ? Have you ever had that moment you just kind of walk into a
27:17 and you're like, why do I in here? That's the brain
27:23 They're chewing on things that make you think, Right, this is where
27:27 live. Are you guys gonna believe on that? That's just just our
27:36 going in two different directions. It's really brain spiders. It would be
27:41 of the brain spider. I wish could brain the brain spiders Instead of
27:45 saying that I'm a complete idiot at . All right. But that's that's
27:50 we got here. Right? we have the arachnoid matter. We
27:54 the PM matter. We have all ridiculously we have blood vessels in both
27:58 them. The space space is filled cerebral spinal fluid and it looks like
28:02 webs. Alright. And so their is really to support all those arteries
28:10 veins as they travel between these two . All right now, within these
28:17 it's not being shown in this We're going to see this when we
28:19 to the cerebral spinal fluid is that going to be penetrations of the arachnoid
28:26 through the dura matter. So they're punch up through the dura matter and
28:31 going to extend the subarachnoid space into little tiny bowls. And these little
28:36 bulbs are called the arachnoid villi. right. And so what this is
28:41 a way to get cerebral spinal fluid join with the blood. All
28:46 Now, when I say that that like they kind of mixed together.
28:49 don't So, the way we're gonna hard to do a chicken and egg
28:53 here. So, the way we cerebral spinal fluid is we borrow stuff
28:57 the blood and then it exists as spinal fluid and it's always being made
29:02 the time. And so if it's made all the time, it has
29:05 be removed from this space because it's space. So we're gonna need to
29:10 it back into the blood from where borrowed it. And so the way
29:13 filtering it back, the pathway through we're filtering it is called the arachnoid
29:18 . And I'm gonna when we get those pictures I'm gonna show and say
29:21 there it is right there. That's arachnoid villi. All right. But
29:25 so that you know what they're associated . All right. So, the
29:31 layer is the door. And our cartoonist here did a terrible job
29:34 demonstrating this. It looks like it's one big thick thing, but it's
29:38 it's actually two layers of very, thick tissue laid up against each
29:44 And so you have one that is to the bone when that's next to
29:48 the arachnoid matter. And so we have names for those two layers.
29:53 have one that's called the gaseous And then we have or the periodical
29:57 . And then we have the meningioma that's right next to the man inks
30:01 arachnoid matter. Now. The way can think about these things if you've
30:06 used a ziploc bag, like a freezer, ziploc bag. You know
30:09 I'm talking about how thick that That's what it feels like. It's
30:13 thick, very tough, very in . It sits there right underneath the
30:17 and it doesn't follow the contours of brain. Like the PM matter.
30:22 the arachnoid matters is kind of the way it's very thin, but it
30:26 kind of sits there so that you that space. And so with these
30:30 dura layers, they're closely they're in opposition there, right up, smack
30:34 to the arachnoid matter. And you the subarachnoid space, then you have
30:37 pia matter. But that tough elastic is what helps protect that soft gooey
30:44 that we call your brain. All now, they're always gonna be closely
30:49 with each other except for some very locations. And again, the picture
30:53 not gonna show it here. But we look at the cerebral spinal fluid
30:56 , I'm gonna hopefully identify where this . We have these areas that are
31:00 where they separate out. So, can imagine here's my two layers and
31:03 going along and then all of a they're gonna widen out like this and
31:06 create this kind of the space in them like that. And so that
31:12 is what is called a dural sinus that dural sinus acts as a vein
31:19 the brain. I didn't mean to , but I did. All
31:25 So what we're gonna be doing is going to see these spaces filled with
31:30 that's going back towards the heart. gonna see arachnoid villi punching through into
31:35 sinuses. So that cerebral spinal fluid then be joined back to the back
31:41 the blood. And that structure is made or created by these dural
31:48 And they're all over the place we . We'll see that they're all over
31:53 right. They don't have any so they don't act like they don't
31:57 like veins. They just basically serve a way to blood to be collected
32:01 they drain back down. And actually is where as I said, CSF
32:06 going to be joined back with the . So, we got these three
32:14 outside in dura matter. Arachnoid matter Matter with the subarachnoid space between the
32:20 and pia. If you want to the way I just thought it PM
32:23 . Subarachnoid space. Arachnoid. Okay, drawing it out, makes
32:30 easy how to draw a line, . Space line. Okay,
32:38 within the brain, what we have we have this empty open space called
32:44 ventricle. There's actually several ventricles. starts off very early on in
32:51 All right, basically, your brain a tube that extends and then gets
32:56 , really complex and folds over And so we get these structures that
33:00 these kind of really unique shapes. venture coals are where the cerebral spinal
33:05 is being made. All right. so what we're doing is we're looking
33:09 a side view and then we're looking a frontal view All right. And
33:14 you can kind of see here, we have is on each side of
33:17 brain is a mirror image of So you can see on each side
33:20 have ventricles. And then they join and then we have this middle structure
33:25 then continues all the way down through spinal cord. All right. So
33:30 derived from the neural canal. Like said, you start off life with
33:33 neural tube and then that neural tube what's going to get interesting. It
33:39 the canal is the central portion of . We have specialized cells that are
33:44 within the ventricles called panda. Most we're going to deal with what are
33:48 glial cells, which is a class neural cells and animal cells are one
33:54 those glial cells. The four ventricles interconnected with each other as I've just
34:01 of demonstrated here. And they're fairly . Alright. We start off with
34:05 the two in the front. So here we're looking at the two up
34:08 the top. Those are called the ventricles. So one would be
34:11 one would be right, all The left and lateral ventricle connect to
34:16 third ventricle via the interview. Excuse . Inter ventricular foramen. Now,
34:24 of the names might get a little . But remember what is inter ventricular
34:27 between the ventricles for a man? whole. Alright, so the lateral
34:33 connect via the the in between the , hole to the third ventricle which
34:39 in the center notice it's not very but it looks really big there,
34:45 ? And the third ventricle has between and the 4th ventricle, a pathway
34:50 the cerebral aqueduct. Sounds very fancy . Alright. And then from the
34:57 ventricle you continue down through the spinal as the central canal. Now,
35:04 spinal fluid can escape from the 4th in one of three ways.
35:11 four ways if you count them you can use the central canal as
35:16 way for cerebral spinal fluid to So, it's just gonna keep going
35:20 through that canal and out through the when the canal empties out. But
35:25 either side, let's see if there's better picture here. Well, it's
35:28 and here on either side that point that point, those are called the
35:33 apertures. All right. So, basically just pathways out from the 4th
35:37 that opens up into the subarachnoid All right. What's in the subarachnoid
35:43 besides the brain spiders? And the CSF cerebral spinal fluid. Alright,
35:52 , how we get the cerebral spinal here is through those two apertures on
35:56 side, Down through that central canal the bottom, or through what is
36:01 the median aperture, which is sitting in here Between, say, the
36:08 aqueduct and the 4th ventricle. And we're going to see a better
36:13 in the in in in just a . Alright. So basically can go
36:17 to the sides, out through the or down through the bottom. And
36:20 you're doing is you're you're being fed that sub arachnoid space. And what
36:26 is is there is a circulation You begin here in the fourth
36:30 You move to the third ventricle or I said fourth, move through the
36:34 ventricles, down through the third through the fourth ventricle, out to
36:38 subarachnoid space from the subarachnoid space. going to be pushed through the arachnoid
36:44 into that dural sinus. Alright, you see kind of a pathway
36:49 it will be more visual in just second for those you're going, I
36:52 see anything up there but a bunch great pictures. Oh look here we
36:58 and start seeing a little bit more . So what is cerebral spinal
37:04 It's very clear, very colorless. circulates through those ventricles and they said
37:09 to the subarachnoid space. You can at the little arrows here, all
37:12 all the turquoise. I get the right. That request. Um all
37:18 turquoise is representing cerebral spinal fluid. blew up here is representing the oxy
37:25 in a sinus. Alright, it's showing you one sinus. Alright,
37:32 what we're looking at is those little are showing you the flow of blood
37:36 showing you the flow of cerebral spinal . Alright, so what its purpose
37:40 it? Why do we have Well, first off there's buoyancy if
37:43 a role in protection and finally it stability in the nervous tissue, even
37:49 it's not in direct contact with the tissue, It's in close contact with
37:56 , the blood. I'm sorry, brain um extra cellular fluid is what
38:03 was looking for. So, let's of walk through what this means.
38:07 right, buoyancy. If you jump the pool, are you going to
38:11 or are you going to sink to bottom? Not me. I float
38:17 . Why would I flow? You say it. Go on, go
38:24 . Very polite. I'm fat. what I'm shooting for here.
38:30 I wasn't offended by that. All . Maybe I'll go back to my
38:35 and cry a little bit, but right now, I'm not gonna buy
38:38 right, I'm gonna float. My density is less than the
38:43 So, when I jump in, don't sink to the bottom, I
38:47 stay up on top. If you very, very low fat and high
38:52 density, your density becomes greater than water. So what do you do
38:58 you sink down to the bottom? , so humans can be up up
39:04 down and whatnot. Alright, the about cerebral spinal fluid, it has
39:07 same density as the brain does. so if you took brain and put
39:13 into a tank of cerebral spinal fluid just set it in there. It
39:18 neither sink nor would it float. would just sit. Okay. And
39:23 part of the purpose of the cerebral fluid is to ensure that the brain
39:27 perfectly situated in the brain cavity. , remember, it's not actually in
39:33 cerebral spinal fluid where the cerebral spinal , it's sitting in that subarachnoid space
39:38 in the ventricles, that's as close the brain gets to the cerebral spinal
39:42 . But what it does is it this environment that doesn't allow the brain
39:46 kind of sink down to the bottom the cranial cavity. It basically holds
39:50 and lifts it up, right? the brain doesn't float to the top
39:55 the cranial vault because it has the density. It holds it in
40:00 So, that's when we say it basically allows the brain to sit
40:05 . I like this thing and I remember where I got that. It's
40:07 one of the textbooks that I used use a long time ago.
40:10 remember you got that frame and that's it's about this big at the
40:13 of the skull, right? And the brain had the mass that it
40:18 , it wasn't being buoyant, it sit down on that cranial floor and
40:23 it would slowly ooze down through the and magnus because it's made of that
40:29 , buttery stuff. All right. this prevents that from happening. The
40:35 thing that it does, it serves a form of protection, remember I
40:39 as a shock absorber, it doesn't well. So when we when we
40:43 into things with our heads, that of the brain would move forward.
40:49 because that fluid is in compressible, very difficult for the brain to actually
40:55 against the brain casing. All well, dr wayne. What about
41:02 ? Well, there's a lot of on concussion. So yeah, the
41:05 can smash up against bone but it a lot of work. Almost most
41:10 the concussions that occur are not a of brain mashing into bones. What
41:15 is, is whipping the brain along and creating sheer force of the fluids
41:21 the brain tissue, which caused damages the cells within the brain really kinda
41:27 . So, think of it like if this is my access. When
41:30 hit something, my brain moves in direction so it shears and the water
41:35 goes, wait a second. I'm supposed to be moving, but I
41:38 and that's where it causes the Oh, so, what we have
41:44 is basically something that serves as a or a cushion around. It's like
41:50 the brain and peanuts, styrofoam, , not the credible ones. You
41:58 what I'm talking about. Okay, , stability. This concept. A
42:06 bit harder to understand. All So, remember the cerebral spinal fluid
42:12 not circulating through the brain tissue, sits external to right, you have
42:17 P. M. Matter, you cerebral spinal fluid on this side of
42:21 P. M. Matter that's where nervous tissue is and that's where the
42:24 cellular fluid is. But the fluid and the fluid here can communicate with
42:31 other. All right. They're able pass materials between them and so what
42:38 doing is when differences arise. say we get too many uh too
42:44 potassium. The potassium can then move the extra cellular fluid of the brain
42:50 the cerebral spinal fluid. It serves a conduit to remove materials via bulk
42:56 from the nervous tissue. Now, you thought too hard about this,
43:02 start going wait a second even though haven't talked about yet, then we
43:05 a blood brain barrier that prevents the of materials from the brain to these
43:09 tissues. And the answer is But because of the close positioning of
43:14 two compartments, it allows for unique to take place. Not the type
43:20 exchange that you'd expect from bloodstream. . It's more of a things flowing
43:28 and flowing out to kind of create sort of equilibrium. All right.
43:32 , it protects the nervous tissue from fluctuation. If I put too much
43:38 in the brain, what's going to anyone else? So, I think
43:44 have a certain number of ions. . Those ions are important for what
43:49 of activity. Actually? Say it action potentials. Right? So,
43:59 I dilute out my ions, do think I'm gonna have a problem.
44:05 one of the things that you can is you can move water from the
44:09 into the cerebral spinal fluid and basically the proper balance of ions in that
44:17 . That would be kind of like example of this. All right now
44:25 we're gonna make this, if you here you see these little red
44:28 So here we are in the here we are in the third,
44:31 we are in the fourth of little areas are called the corduroy plexus,
44:36 plexus is where the blood vessels. are basically don't have a blood brain
44:42 and they get really really close to surface to the dependable cells. And
44:46 epidermal cells go, oh well let take this out of the blood,
44:48 me take this out of the let me take this out of the
44:51 . And what the epidermal cells do they make the cerebral spinal fluid.
44:56 , so it's at these particular locations we lack of blood brain barrier and
45:01 the capillaries get really really close to tissues in the ventricles. Alright,
45:08 they're in very specific locations, they're all the different ones. So lateral
45:13 and 4th but they're specifically located. right now again many of you are
45:19 be tempted to try to memorize something this. Don't memorize that chart
45:23 It's just two there for a quick . You can kind of look and
45:26 , oh yeah, they do look lot alike. One of the major
45:29 though, in terms of plasma and is that there is lots of protein
45:34 plasma, very little in cerebral spinal . All right. So in other
45:38 , we're not able to get large out of the blood because there's a
45:43 between and not just a blood brain , but just a general barrier between
45:47 capillaries and the tissues. But if you go and look at this
45:51 for the most part, they're very similar in terms of their makeup.
45:55 right, so very similar in composition plasma plasma. Is the fluid that
46:01 up blood. Okay, the difference those proteins and some small slight ion
46:10 . Mandamus cells basically are taking they're pumping sodium. Here's a little
46:14 wherever sodium goes. Water follows. basically it's following osmotic lee and then
46:20 that water goes in the chlorine wait a second. I want to
46:23 to and it follows the water and just happens to be negatively charged.
46:26 , it's also following the sodium. right. There are other things that
46:31 going to pick up some by simple . There will be other things that
46:35 can do by facilitated diffusion And there's other things you can do by active
46:40 . So you're not solely dependent upon activity. You're not solely dependent upon
46:45 pumping. There are other things that can move along the way that just
46:49 as a result of the mechanisms that in place. But the end result
46:53 that you create this material that is different from plasma. And so what
46:59 gonna do is it's going to start it, it fills up and as
47:02 making it you're creating more so it pressure to drive the fluid forward and
47:08 going to move from the lateral ventricles third through the cerebral aqueduct to the
47:14 , out through the apertures. Here's median aperture, the better picture of
47:18 . I said it was up so me correcting myself, so laterals
47:22 the side, mediums at the back then central is down through the
47:28 Now again, don't memorize his so you make the total space.
47:36 this turquoise stuff all the way around goes all the way down the spinal
47:39 as well is about 125 to 150 . Alright, you make about 500
47:45 per day Looking around the room. one has a 12 ounce. Um
47:52 if you look at a 12 ounce That's rough. Well actually that's even
47:55 right there, the water bottle, up your water bottle Sea water
47:59 that is 500 mils. That's how cerebral spinal fluid you make in a
48:03 ? 1:25 is a quarter of So how often are you replacing your
48:09 spinal fluid daily? four times a mind. Simple Math. Alright,
48:15 , you are constantly making cerebral spinal . So, it means there's this
48:20 flow going from the lateral to the , 3rd to the fourth, out
48:23 the subarachnoid space, pushing it up around. And then here there
48:29 That would be a village. There's things called granule ations which are labeled
48:33 basically that's what it is. And going out and you're being pushed back
48:36 the blood. If you didn't have , basically, you imagine that space
48:41 just start filling up with fluid until popped. Which would be after the
48:46 day of life. Does that not sense? If you're always making
48:51 it has to go someplace. All . So, that's what we're saying
48:55 So, this is where it's It's you've made enough to fill this
49:00 . But as you keep making it's eventually going to flow in and
49:04 has to go out back to the from which you borrowed it. And
49:08 did we borrow it from? When borrowed it here at the corporate
49:12 We took things out of the blood We want water. We want
49:15 We want this. And we made spinal fluid. And then what we
49:18 is we turn it all back to blood. Yes. Go back.
49:27 , this is what this is saying formed in the coral plexus via blood
49:31 the capillaries. Capillaries are the smallest of exchange. All right, How
49:40 flow occur? Well, epidermal cells cilia. So what does cilia
49:47 Right? How you sit, how stand, how you walk? So
49:53 factors play a role, right? standing up right now. Gravity has
49:59 effect on moving that cerebral spinal If I lie down, gravity has
50:03 different type of effect, but it causes that movement. And finally,
50:08 result of all of this is that have a positive pressure about 10 of
50:15 . Now, some of you we'll an opportunity in your life to go
50:19 in an operating room and you'll get watch an epidural. Haven't you ever
50:23 an epidural epidural is when they put . Usually it's anesthesia to the space
50:32 the spinal cord, right into the spinal fluid. So what they do
50:35 they take this needle, they basically where the hip is and that means
50:39 take you to the right vertebrae, have you bend over really, you're
50:42 your side like this kind of bent and they take that needle and they
50:46 right into that space. If you needles, it's awesome to watch and
50:55 what they do to make sure that got it in the right space?
50:58 can pull out a little portion of needle that sits through and you get
51:01 watch the fluids exit out. It really, really slow. It's
51:05 oh we got it in the right . And if you take out that
51:09 internal needle and nothing's flowing, you get in the right space and you
51:12 it back in, you take it , put it in again.
51:18 hopefully you get it done the first . You might take two terms.
51:22 . But the reason that you see bubble of fluid is because there's there's
51:26 natural pressure to drive that fluid And there's only one path through which
51:31 can exit those arachnoid villi and the graduations. Here's a bigger picture so
51:42 you can see what we just talked . There's granule ations here. You
51:45 see the quarry plexus, lateral, , 4th ventricle. Here's the median
51:51 . It's just showing you the There's central canal, all this stuff
51:55 that subarachnoid space. Just keep moving and out. You go in terms
51:59 the flow. Okay, we're good that. Yeah. Okay, so
52:08 takes us down to that last I was talking about that that that
52:12 that just is just kind of All right, because I said this
52:16 both a physical barrier and a physiological . All right. And so what
52:21 does it limits what can move in out of the blood. And when
52:25 say it's a physical barrier. It's physical barrier because of the way that
52:30 cells that make up the, the and the cells that are found in
52:34 brain tissue come together to basically create wall between those two spaces. All
52:43 now, as we mentioned, things into the brain can have a heavily
52:48 effect. I had mentioned water. I get to tell you the story
52:53 A couple of years ago, what about the time I started teaching here
52:57 about 2007, Do you remember You were very, very young?
53:02 when the we came out. Nintendo, we, you know what
53:05 is? You know, people oh no, alright, it's a
53:09 game console at the time it was the PS two was out, Xbox
53:13 came out. Everyone thought that PS and Xbox were like the, the
53:16 things ever. And the Nintendo kind snuck in and said, hey we
53:20 this thing and everyone went crazy over we and you couldn't find them anywhere
53:25 it's a Nintendo and who knows whatever excuse they had. So this Christmas
53:31 one can find, we's anywhere and was a contest in California and it
53:36 called, who knows what I always the P for the week contest.
53:40 . It's one of those contests where know, it's like if you put
53:43 hand on the truck and the last to take their hand off the truck
53:46 to keep the truck. Yeah. Mr Beast does this type of stupid
53:50 all the time. I've got four . I'm familiar with Mr Beast,
53:54 ? But, you know, there's sort of silly contest, right?
53:57 this was like a radio station that oh, we got we got we
53:59 ahold of a we And so, we're gonna do is we're gonna see
54:03 gonna get the we were gonna give a gallon of water, Everyone's gonna
54:06 the gallon of water. And the who goes to the bathroom last wins
54:11 we a simple contest, right? , you have all sorts of people
54:15 this contest. There was a young or a mother or whatever who was
54:19 little bit petite, four ft all right. And she had to
54:24 the same amount of water as everybody . And when you drink water,
54:27 first place water goes. When it in the mouth that goes into the
54:30 from the stomach, it goes into bloodstream, and then it disperses itself
54:34 quickly as it can go into all other systems, right? This could
54:39 a while before the kidney starts churning that extra water. It's not like
54:43 drink water and go straight to the , and I p it takes a
54:45 bit of time. And when you a lot of water like that,
54:49 has to disperse itself in the body , including the brain tissue. And
54:55 now, see where the problem So, there's a petite woman who
54:59 it in your in your body. have about 5l of fluid. All
55:05 . So, you can already see going on here. And so,
55:08 her brain ceased to function properly. respiratory centers and her cardiac centers started
55:14 fail. And so she basically her stopped and she stopped breathing. And
55:19 died for a video game console. right. And so, you can
55:25 why things like this are important. , obviously, this doesn't help with
55:29 , right? Water has this kind a special ability to kind of go
55:33 everywhere. All right. But you imagine other substances. Can you think
55:37 other substances that affect the way your functions? Alcohol is an easy
55:43 right? Because it's just like water go wherever it wants to. All
55:47 . But you can also think of are chemicals that I can take that
55:50 affect my brain. Some of them prescribed herbal, some of them not
55:54 prescribe herbal, right? But part the reason that we have these chemicals
56:00 can affect our brains. So, have this barrier to kind of prevent
56:04 from getting into our brain that can us harm. And that's the purpose
56:08 this. So, let's talk about anatomical restrictions anatomically speaking, we have
56:21 type junction. So blood vessels are up of epithelium. And then the
56:25 picture here, the red structure alright the cells of the epithelium. Now
56:33 know we haven't talked about blood vessels . And so I might even be
56:37 words here, you're like, I even know what you're talking about,
56:39 I want you to take your hands a second. I want you to
56:42 cutting in your hand a bunch of , right? And and and they're
56:46 a I don't know, pail or of water. You go in there
56:51 you scoop out the marbles and if don't put your fingers really close
56:55 you're gonna end up with a whole of marbles, but not a lot
56:57 water in your hands. Right, . So that's how most capillaries
57:03 Alright. The cells have spaces in them. They're not big spaces because
57:09 I can hold onto the marbles but molecules can escape between them.
57:14 that's a normal capillary. What happens the brain is that there's an association
57:20 these astro sites and the astrocytes tell capillary cells these epithelial cells, we
57:26 want the spaces so we want you to kind of hold your fingers together
57:31 then do the same sort of sort scoop when I pull out now with
57:34 fingers held close together. I now water cupped in my hands because there's
57:39 way for it to escape. And kind of what's gone on up in
57:44 brain is the astra sites Tell the to modify their relationship. So you
57:50 these tight junctions instead of I hate word but we use it leaky tight
57:56 that you see everywhere else in the . Yeah, I know it's
58:00 All right. The second thing that see and that's what this yellow represents
58:05 . No, that's actually a Um What you also see here is
58:09 see a very thick basil Ramona. you recall, basil lamanna is simply
58:14 proteins that are found between connective tissue epithelial tissue. Right? You had
58:20 basement membrane. So you had the lemon and he had the basil
58:23 So the basil lemonade is the epithelial . So here you're also telling these
58:29 cells we want you to make a layer. So you can think of
58:32 this. I'm putting a screen door the cells and the other tissue.
58:37 I've got blood, I've got I got a thick screen door and
58:40 I've got my my nervous tissue over . So if I have something that
58:46 , not only does it have to through the sell it now has to
58:49 through this thick screen door and then top of that the astro sites which
58:54 doing all the communication basically tell I basically what they do is they wrap
58:59 around those capillaries to create a third . So now you have here's your
59:05 . You have your epithelial cell. have your basement membrane and you have
59:08 astro sites. So anything that wants move from the blood to the tissue
59:12 to pass through all of those layers either direction. Now in order to
59:18 through that, that means the epithelial cells have to have the right
59:23 That means the astrocytes cells have to the right receptors. And you have
59:27 tight junctions that don't let you just in between them. So now you
59:31 kind of see, oh not only I have something physical, like a
59:36 cell after cell after cell that gets the way I have something physiological.
59:42 it wants to get into the I better have a receptor for
59:46 Right? So the only things that pass through from here to there,
59:53 you can say from in here there are those things that are um
59:59 lipid soluble or something that has a that is water soluble. Right?
60:05 if I want to move glucose, you think the brain wants glucose?
60:09 yeah. That's why we eat Because the brain demands it, give
60:14 the sugar. Right? In order the glucose to get into the
60:18 there needs to be a receptor that up glucose on the inside of the
60:22 crosses it across the inside of the releases it on the other side,
60:27 works its way across that thick basement and then gets picked up by the
60:32 site by another receptor that then transports across through that salad releases out into
60:37 brain tissue. That's physiological. if I'm lipid soluble, there is
60:46 a cell membrane in the body that keep me from passing through it.
60:52 ? So if I'm a steroid for , that's an easy one. Since
60:55 learned steroids or lipids, all I do is be in the blood,
60:59 I don't want to be in in first place. I'm like, I'm
61:01 booking it and I'm like, oh just gonna work through all this stuff
61:04 I have no problems getting across the . Now there are a lot of
61:09 that we take that can work on brains. So what do you think
61:14 the type of drugs, What do think their characteristic is are they water
61:19 or lipid soluble? Their lipid So, if you're planning on a
61:23 in pharmacy all of a sudden you've created a very simple way to
61:28 the classes of molecules that you're gonna for drugs for the brains, they
61:34 to be lipid soluble. It's kind interesting. Right? The last thing
61:41 want to point out there is also cells called parasites. Perry means next
61:44 so cells that are next to, basically helped coordinate all the signaling that's
61:49 on within all this stuff. So have the blood brain barrier. It's
61:57 blood vessels. Alright, what's the we'll get to that a little bit
62:01 basically these are tight junctions regulated by parasites. The astrocytes? Very,
62:05 selective. Do you have blood brain at the court of plexus? There's
62:11 it's tight junction but that's about Alright, we don't have the same
62:15 of control and that allows us to cerebral spinal fluid and then there are
62:19 of the brain that don't need or want blood brain barrier. And
62:24 these structures are not going to be important to you right now. But
62:27 gonna start making sense when we start about the hypothalamus is the master control
62:32 for hormones. And so what it's is constantly sampling the blood to determine
62:36 hormones need to be released. So samples the blood. So you don't
62:40 a blood brain barrier in the Otherwise wouldn't be able to sample the
62:44 gland is also another gland that produces . So it needs to have access
62:49 contact with the blood. We the corot plexus must be permissible and
62:55 the last one out of the vomiting . All right. The most likely
63:00 you're going to become poisoned in your is you're going to consume something,
63:06 ? That's that's the likeliest way you're to put a toxin in your
63:12 Alright, so the body is looking things that cause harm to it and
63:17 the vomiting center is just kind of at that and when it comes across
63:20 it says oh well I know where got that, you probably consume
63:24 you idiot and so go throw it and so that's what you do is
63:26 throw it up so when you get by a rattlesnake toxins are circulating in
63:31 body, brain says what do I with this? Well you probably consume
63:35 , you idiot. And so it you throw up right, That is
63:40 our body deals with toxins. No whenever you I feel nauseous and I
63:48 say that's that's the outcome. But you do some sort of relative harm
63:52 yourself right? Like getting in one those spinny things, you know it's
63:58 how did I get so confused and is my brain not behaving correctly?
64:03 says oh I know what you He ate something, you idiot.
64:06 throw it up, that's why you up. It's not like oh don't
64:11 in this thing. So vomiting center for poisonous substances. So very very
64:22 . Alright, we're getting down to nitty gritty here so far, you
64:26 all with me here. So we've three protections, we have the
64:32 right? We had CSF and then had the the BBB so we've got
64:41 whole bunch of, we got we got you know just abbreviations everywhere
64:47 again, that's an endoscope, So let me just just kind of
64:52 these out about how things are carried . Just so that you're clear of
64:56 physiological So when your lipids, lipids can pass through lipid bi layers
65:03 problems. But they don't necessarily they're particularly happy about being any sort of
65:09 that's watering. So they usually have sort of carrier. Now, what's
65:13 is that there are things that actually that receptors and so there are ways
65:18 you can actually transport fats from one to the other. But generally
65:23 they move through the layers just I'm trying to see where this
65:27 It transito sis sis Yes, there's little filling. So it's basically
65:36 look, here's the molecule, it passes on through. Nothing can stop
65:40 . It's just moving down. Its gradient, carrier mediated. And the
65:45 here, oxygen steroids, some drugs mediated. So, what you're gonna
65:51 is you're gonna need something that allows to pick it up and carry it
65:55 carry it across. All right, things like glucose amino acids,
66:00 small peptides. These are things that have to have a specific molecule that
66:05 , I see you, I want I grab you and I move you
66:09 and that's what's going on here. also have mediated uh excuse me
66:16 Media. And transport here, you see there's a receptor, there's a
66:19 we're trying to move it gets pinched . You get a vesicles vesicles then
66:24 um used to move across the membrane the cell and then it's put out
66:28 the surface and then it's released and to move forward. So, things
66:32 you see here, these are larger substances, things that are too
66:38 for carriers would use these types of . And then there's the very
66:43 like water can pass in between the as an example that also has auction
66:49 their carbon dioxide and other gasses can that well. Mhm. They can
66:54 that everywhere. All right. This the last little bit to me.
67:03 is the stuff that I think is because memorizing whole bunch of names is
67:08 a lot of fun. That's how see it. All right. But
67:11 what this is. Is we're really be looking at some very specific blood
67:15 . There are lots of blood vessels were not naming. There are lots
67:18 blood vessels on the slide that we're naming. And I'm just trying to
67:21 this as simple as we can so you can understand how the brain gets
67:26 blood. All right. So, traveling away from the heart always is
67:30 the artery. Blood traveling towards the is always via vein. So,
67:35 we're looking at here is solely So, blood going to the brain
67:41 from the heart. All right. , if you look at blood
67:47 you could say if I take a line, I can divide the brain
67:51 an anterior portion and a posterior Alright, so we can literally divide
67:56 brain in half. We have this structure in the brain. And I'm
68:01 say this like with 100% confidence that in the world has one of
68:06 The truth is there's only about 80% us have this, but we're just
68:09 pretend like all of us do. , It's called the Circle of
68:12 named after the guy who discovered Not after the guy on diff'rent
68:17 Thank you for laughing at the only . No one gets it. All
68:22 . So, that would be the of Willis right there and we're gonna
68:25 gonna look at a little bit closer the next slide or two slides away
68:29 with regard to the anterior segment. . So, remember you're looking at
68:35 coming towards you, right? you can imagine I'm lying down.
68:39 you can see we have the carotid travel up the neck, and then
68:45 they do is they then penetrate into anterior portion of the brain.
68:50 And this portion of the brain that looking at here is called the
68:55 All right. And so that internal . So here you have the internal
69:01 , it's right? There is What they do is they split So
69:05 split number one. They're split number . They're split number one? They're
69:08 number two. Split # one and are the Anterior cerebral artery. So
69:15 is it going to the cerebrum? the anterior one. There's also a
69:20 cerebral artery. Alright, so that's middle one. That's the anterior
69:25 And there's also a posterior one that's being shown in this picture. All
69:30 . So internal carotid Anterior portion of brain splits into two. Anterior cerebral
69:38 , cerebral Okay. And it's feeding front part of the brain with regard
69:44 the posterior segment. You look at and you're going, man, there's
69:46 lot of stuff there and there But we're going to try to make
69:49 simple what we have. Moving This is your spinal cord moving along
69:56 length of the spinal cord. We a couple of different arteries there.
70:00 right, you can see here we an anterior spinal artery. We're going
70:04 have these two paired arteries which are the vertebral arteries. We want to
70:08 on those two vertebral arteries because they're up towards the brain, basically moving
70:14 the spinal cord and they come together join and form this larger artery called
70:20 basil or artery. So, you think of the basal artery basically sits
70:25 the base of the brain. All now, this region right here is
70:29 the brain stem. Right? This right down here is called the
70:34 Not to be confused with the All right. And so the names
70:38 the arteries are based upon what they feeding into. Alright, so the
70:44 or artery. This thing right here all the little spider legs coming off
70:48 it have a couple of unique We have this artery, this paired
70:53 right here. They're called the anterior sara Bella arteries. So they're feeding
71:00 cerebellum, not the cerebrum, which what these are cerebral. All
71:07 sara bellum. The difference between those cerebrum, cerebrum and cerebellum. Cerebellum
71:12 little brain. Cerebral means big brain just brain. Okay, So anterior
71:20 . What a confusing name. So you hear think anterior, what do
71:23 think of this direction? Right. what do you think of when you
71:27 of inferior down? So it's the and below sara Bella artery. That's
71:36 it's getting its name from. All . We have the pontin arteries,
71:41 tiene refers to the ponds. Which is part of the brain stem
71:46 that's what they're doing. Is they're the blood to the ponds and then
71:50 have the superior serra bela arteries. this is above the cerebellum.
71:56 so the superior cerebellum, you can right there there. So, and
72:06 blood flow. You know, we the dural sinuses and stuff and we're
72:10 getting to that just yet. When leaves the brain, it returns back
72:15 the heart via the internal jugular. an easy one. Right.
72:21 This. You're going for the jugular , that's what vampires like to suck
72:29 . How is that? All right I mentioned the post here is
72:36 You can see it here, And what this picture is, just
72:41 to show you is kind of where blood is going. And you can
72:45 of see, oh if this is cerebrum, that little thing right there
72:49 the cerebellum. What you're looking at there is part of the brain stem
72:53 then down here would be the spinal . So, if this is the
72:57 you can see that the anterior cerebral deals with the anterior portion of the
73:02 , the posterior dues with the posterior the middle deals with basically everything
73:09 So, they're well named because they blood to these regions of the
73:21 The circle of Willis, as we , we're pretending like everyone has
73:26 All right, basically allows blood to both the anterior postaer portion of the
73:32 . Even if one of those pathways blocked. So basically blood can circulate
73:38 this and go back here to provide to the post here regions. If
73:44 is blocked. The converse is true well. If something up here,
73:49 of the critics gets blocked then blood flow via the circle of Willis to
73:53 other structures. That's the whole purpose it the cell. Or excuse
74:00 the artery that plays a role in the connections is the anterior communicating.
74:07 , I got that wrong. It's there. That's anterior cerebral Where's the
74:12 communicating? The basal artery, as mentioned, arises from The two or
74:21 Rolling The Spinal Arteries. So there's couple of them that are named that
74:26 need to know and all the rest them. And I'm not going to
74:30 like you look at a picture like and you guys panic. It's actually
74:34 of the one of the worst things textbooks do because they don't have the
74:39 and so they just take a picture they show you everything on that
74:43 So even if it's not all you get this cognitive distance going too
74:49 . So just focus on the ones I've highlighted for you. All
74:55 Now, the last two slides just kind of to help us move
74:59 then. We're just done All We've talked about neurons already.
75:04 We've talked about nervous tissue consisting of or neurons and these support cells called
75:10 cells. We mentioned those very, early on and I said we're gonna
75:13 back to all this stuff. The that's primarily seen in the nervous tissue
75:19 we've been looking at. The central central nervous system is called a pyramid
75:26 all right now, not all nervous has pyramid cells. You know,
75:31 we look down through the spinal we're going to see the multipolar
75:36 All right. Which is really kind everything that we're looking at. So
75:40 cells are a type of of multipolar , but they have these unique shapes
75:45 them. You can see Soma It like a pyramid. All right.
75:51 have large dendrites and then they have very large single axon. And so
75:58 we're looking at this nervous tissue in gray matter, you're going to see
76:03 these are pyramid cells that are in communicating with each other. Just like
76:08 been talking about with this stuff over . All right. So, we're
76:12 to see these primary in the frontal or the prefrontal cortex as well as
76:16 cortical spinal tracts. We're going to to that in the next unit when
76:20 start talking about it. But I to familiarize you with this type of
76:24 and why is this important? Because sitting here listening to me and understanding
76:29 a result of those pyramid cells working your head right now. All
76:34 So, we're going to stop there we come back. The first thing
76:37 gonna do is we're gonna talk about cells. Alright. So we're gonna
76:42 about the Astros site which we've already . We're gonna talk about dependable
76:45 which we've already mentioned and we're gonna working from there. Have a great
76:52 . Okay, So, and basketball ,
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