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BIOL 2302 Human Anatomy & Physiology II - 2302_lecture06_0202
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00:08 Alright, good morning. Here we . Nice cold day here in H
00:15 . I know it's not like cold but this Houston, we've been talking
00:23 parts of the cardiovascular system. We with the blood and we said what
00:28 was made up of. Then we onto the pump that pumps the
00:33 And so we talked about the heart all its parts and how it
00:37 And today we're going to actually deal the vasculature finally. Alright. And
00:41 already learned the names of these But we're gonna do we're gonna dive
00:45 deep and actually understand what they right? And then we're going to
00:51 from structure to dealing with blood flow blood pressure. Now, if you're
00:58 aware, I think you all are you're all smart is in a
01:02 We have what an exam. Oh goodness. Yeah. A week from
01:08 . We have an exam. If haven't signed up, you're probably gonna
01:11 stuck with a crappy time. I know if it's a crappy time,
01:15 for some people it might be so sure you've signed up. Uh just
01:21 that you know, um I need put this on blackboard uh casa has
01:27 new makeup policy and um it's not clear how it works to me,
01:32 it's very limited on how they're going allow makeup. So if you are
01:37 , understand your window for making up is going to be a little bit
01:41 than it has previously. All So just letting you know I'll post
01:45 on blackboard that's not gonna affect like of you. But someone's gonna be
01:51 got the I got the covid that can't covid and the answer is
01:55 But there is a specific time that going to allow makeups. Alright.
02:01 with that in mind, you got nervous look on your face like
02:05 All right. With that in Let's let's do something fun. Let's
02:09 about some physio or some anatomy. ? I mean that is that more
02:14 ? You guys you look like you've been shot like yes, it's rainy
02:20 it's cold. But just think after rain and the cold, then all
02:24 water is getting absorbed in the ground all the flowers are gonna be happy
02:27 about two or three weeks and it'll beautiful for like a week and it'll
02:31 hot human again. There there's the I'm looking for. Okay,
02:36 so this is our starting point. we said that we have three different
02:39 of blood vessels, arteries, by definition are those vessels which carry
02:44 from the heart. And then we're add a little bit to the end
02:46 it to the capillaries. Capillaries is we're gonna spend most of our time
02:51 we're dealing with the vasculature because that's all the action happens. Capillaries are
02:56 , very small. They're very And this is where exchange takes
03:00 And so this allows for materials to from the external environment to the cells
03:05 your body and from the cells of body to the external environment.
03:09 that's a really simplified version of But this is where all the action
03:13 happening. All right. And then , blood from the capillaries is gonna
03:17 moved back to the heart via And so, if you understand that
03:22 , everything else just kind of falls place around it. All right
03:27 it's always happened like that. There a general structure that we can use
03:33 a model on which we build the of all the different vessels that we're
03:38 be talking about. So, arteries veins and capillaries share this general
03:44 Alright, now, it says arteries veins up here, and it doesn't
03:48 capillaries because capillaries are coming unique in While you would say that they have
03:52 32 of those three are basically non , that we basically say there.
03:58 . But you'll see that they you're in subtract based on this. All
04:02 . So, we have what are the tunics and you'll see them labeled
04:08 . Alright, so, tunics are three different layers. So, we
04:12 a tunica in tema, a tunica and a tunica external and in
04:18 What does that mean? External. and middle tunics. Now, what's
04:26 is the composition of these different Alright, now you're saying,
04:31 how can this possibly be interesting? , it's this structure that gives rise
04:38 the functionality of the vessel that we're at. All right, So,
04:43 why we're kind of interested in Because what makes an artery and artery
04:47 not the fact that it just carries from the heart to the capillaries,
04:51 its structure that allows it to do and similarly, with the veins and
04:56 capillaries, it's this structure that allows to do the unique thing that it
05:01 . Now you're gonna hear the word over and over and over again when
05:04 talk and so, when you hear , what you need to be thinking
05:09 helps when I turn this on is talking about the space on the inside
05:15 the vessel. Alright, So, of it as the inside of the
05:20 . Alright. If the vessel is pipe, the inside is the
05:24 Alright? It's just the open space which the material actually travels.
05:28 we're going to see two slides that exactly the same with two different
05:32 So, this picture is a picture what what's red. So, it
05:34 to be arteries. This picture is , so, it has to be
05:41 . Alright, so, it doesn't notice how the text doesn't change.
05:43 want to go back and forth. just a picture. So, this
05:47 exactly true doesn't matter if you're looking the artery or the vein.
05:54 This what I'm about to tell you true for both of them. All
05:57 . So, the inner layer is the tunica intimacy. You can see
06:02 here's the lumen. There is that inner layer. That's the intimacy that
06:08 is made up of a squamous epithelium indo thallium. Alright, we've heard
06:14 word already used once before. You not remember because I didn't make a
06:17 deal about it. But the indo is the epithelium of the vasculature.
06:23 makes up the inside of the It makes up the inside of all
06:26 blood vessels. All right. it is the epithelium now underlying
06:31 Or what you say is as you're outwards. So, there's little red
06:34 that you see here is the sub layer. And so this is connective
06:40 , its basement membrane. It basically that epithelium to the next layer,
06:46 would be the tunica media. All now, the purpose of the indo
06:51 is to create a a friction And it's not gonna be 100% friction
06:56 , but a frictionless surface over which blood can flow. All right.
07:02 , lack of a better way to it. It's a slip and slide
07:05 of of the blood vessel so that blood travels down it doesn't it doesn't
07:10 . It moves evenly and quickly along surface. It's not 100% frictionless.
07:16 actually has some friction which is very to how blood flows in the
07:20 but it's less friction e than the of your epithelium. How's that?
07:26 , the tunica media is a layer smooth muscle. It's not just one
07:31 , it's multiple layers. So it's you can just think of it as
07:35 rings of muscle that goes around the vessel. Now, the reason we
07:39 this is for the purposes of creating smaller space or a larger space through
07:44 process of vessel constriction or visa Constrict means to make smaller. So
07:50 make the tuna, the lumen smaller vessel constriction and invesco dilation. You'd
07:56 the looming larger. Alright now, just to make sure we're on the
08:01 page. So, if I made loom and smaller would I increase or
08:05 the volume inside the blood vessel And if I make this, if
08:10 dilate, would I increase or decrease volume increase? Right? So dilate
08:17 it bigger. So that means there's space. So that means it can
08:21 more blood or blood can flow. blood can flow through it similarly,
08:26 I make it smaller, that's less , so less blood can flow
08:31 All right. And this will become in just a moment. I want
08:34 want to make sure that we understand the terms mean. Alright, so
08:38 media is smooth muscle so far, easy inside is epithelium. Middle is
08:43 muscle outside. What is that? primarily connective tissue and it's different types
08:49 connective tissue. The purpose of which to ensure that we have something that
08:55 the blood vessel from expanding too It also anchors the blood vessel where
08:59 needs to be, and it protects blood vessel. All right.
09:03 you might see in larger blood So, like in this particular case
09:07 here, you can see there's there might even be small blood vessels
09:11 the tunica. External. All Because there are cells there. And
09:15 need nutrition and materials in order to . And so, you need to
09:20 them with blood. So, you have a blood vessel for blood
09:22 Alright. But there's much, much . Alright. And those type of
09:26 vessels are called vis a vis a a vis or um And what does
09:31 mean? Blood vessel? The blood ? All right. So,
09:38 and a helium middle musk. I'm feeling like Popeye today. And
09:47 on the outside connective tissue. All . Now, that's for an artery
09:54 vein. Is it different? it's exactly the same. So,
09:58 doesn't matter where you are. All have these three layers. Alright.
10:04 It's construction. That is unique. right. So, let's take a
10:08 at the arteries and see what we . That makes them unique.
10:13 Now, arteries, as we extend from the heart and travel down
10:18 the capillaries. All right. As are moving from the heart down to
10:21 capillaries. The lumen of those vessels smaller and smaller and smaller. In
10:27 words, you start off with big and when you get down to the
10:30 , you got itsy bitsy teeny tiny . Alright. So everything is getting
10:34 the further away you move from the . All right. Now, the
10:39 thing has to do with the composition these tunics. Alright, As you
10:46 from the heart, you're gonna see decrease in the relative amounts of the
10:52 tissues or elastic fibers that are found the connective tissue. And you're going
10:56 see an increase in the relative amount smooth muscle. Now, let me
11:00 that into english for you. And that means if the blood vessels were
11:04 same size from the top down to bottom. Right? So, they
11:08 change size. What you would see that the elasticity of the blood vessel
11:12 the elastic fibers are going to decrease as you move down. But as
11:17 move downward, the smooth muscle is get thicker and thicker and thicker.
11:22 right, because, remember this is , right, relative size or relative
11:27 . Now, what's really happening is that the smooth muscles staying more or
11:31 the same size? The amount of fiber is getting less and the vessel
11:38 is getting smaller. So, between two things, it looks like the
11:41 muscles getting bigger. That's kind of what's really going on? All
11:47 So what we say with that in is that there are three different levels
11:52 arteries in the body. First is we refer to as the elastic
11:57 The second is going to be the artery and the last one is the
12:02 artery called the arterial. See it a cute little name arterial, maybe
12:08 was a princess. All right. with the elastic arteries. These are
12:16 big bad boys. These are thick , they sit up here nearest the
12:20 . They're sometimes referred to as conducting . The prime example of this is
12:25 aorta and the branches off the aorta also these types of arteries. Alright
12:32 their purpose is to serve as a reservoir and the reason they're pressure reservoirs
12:39 they have lots and lots of these fibers in that tunica external. So
12:45 that means is if you push fluid them, they don't resist what they
12:50 is expand like a balloon and now have potential energy to drive the fluid
12:58 as that elastic relaxes and the resistance the other side relaxes. So this
13:05 what allows your blood to move forward your body after the heart pump because
13:08 heart goes through this phase of contraction relaxation. And if the heart goes
13:15 contraction relaxation. So basically pushes and relaxes. There's many periods of time
13:20 blood shouldn't be moving forward in your . Right? Does that kind of
13:24 sense to you? Right. these help to preserve the flow of
13:30 as the blood is pushed out of heart because you basically stretch this vessel
13:35 a rubber band and now that energy in the walls and it's used to
13:40 the fluid forward while the heart's That's your job. Okay.
13:48 what they're gonna do is as you further away from the heart, they're
13:51 begin to branch and form what are the muscular arteries. Now, why
13:55 their muscular arteries? What happened to how do we change from elastic,
13:59 muscular? What do we lose We lose the elastin. And
14:05 the muscular arteries are what you're probably familiar with. Alright, when you
14:10 like the renal artery, you or a named artery. Hepatic
14:16 Alright, Whenever you see like a name like that, these are the
14:20 arteries. All right. These are distributing arteries. They move the blood
14:25 the organs that need to get that . All right. And so,
14:30 are losing that elastic nature. And , what you have is you have
14:36 and because you have more muscle than have elasticity, that muscle has a
14:40 effect on the flow of blood because can do two things with that
14:44 I can contract the muscle or relax muscle which we called vessel constriction and
14:50 . So, what I can do I can beso dilate and allow more
14:53 through or I can constrict to prevent flow of blood. And what I'm
14:57 here is I'm creating resistance. All . So, these are the vessels
15:02 have a major role in producing resistance flow in the with regard to the
15:09 themselves. Alright. So they have They have less elastin but they're still
15:17 in there. They're not completely devoid it, but they have less less
15:21 it. Let's see. Um and I guess the last thing I
15:26 to point out here is they have they branch into the arterials.
15:32 so, elastic arteries are the pressure moving down into the arteries and then
15:40 into the arterials. We're now dealing resistance vessels and then we get down
15:45 the arterials. Either the smallest Alright. The largest of these because
15:50 multiple sizes. All right, you're have bigger arterials and then you're gonna
15:54 smaller arterials. The biggest of you're gonna see have all three tunics
15:59 . You're gonna see the tunica interna media tunica tunica external. They'll be
16:05 identifiable connective tissue muscle in a but as the vessel gets smaller and
16:10 and smaller, what ends up happening you end up losing layers of the
16:14 muscle, you lose the tunica external really what you're stuck with is the
16:19 in tema with just a couple of of smooth muscle around it.
16:23 they're getting really, really small but speaking, they have a lot more
16:27 than the ones that you're starting off those elastic arteries. All right
16:35 these will always have a certain degree muscular tone to them. In other
16:41 , they don't sit in a relaxed all the time. Your blood vessels
16:45 always working is the way you can about it. So they kind of
16:48 in the state that's in the middle completely jacked and like contracted and completely
16:54 and not doing anything. They're what refer to as vezo motor tone.
16:59 they sit in the middle. So means you can do things with
17:02 All right. And what their job is the arterials is to determine blood
17:08 into the capillaries. So, capillaries a little bit unique. They're not
17:14 in like some sort of order where like artery, you don't go like
17:17 big smaller, smaller, smaller than into capillary. Now, what you're
17:20 is when you're dealing with capillaries, dealing with a network a a mesh
17:27 vessels that are kind of spread all the place. And so what you're
17:31 to do with the arterial as we're to see here is blood is being
17:35 into different directions based on need. right. So the idea is
17:39 oh, those cells over there saying need nutrients. Okay, I'm gonna
17:43 up the blood vessel to allow blood flow into that. But I'm gonna
17:46 over here because they've been saturated with and glucose. Okay. Oh well
17:51 one is now telling me it needs . So I'll go ahead and open
17:53 that and then I'll stop the flow blood over here. So I'm just
17:57 constantly move blood to where it needs go. And that's what the arterials
18:00 primarily doing. They're deciding where the goes now. They're not deciding they're
18:05 told where the blood goes and who's them the cells? All right,
18:11 that's one of the one of the things we're gonna see here again in
18:14 a second. I know I'm kind jumping ahead. Is that the determination
18:19 where blood is gonna flow in your is gonna be determined by the needs
18:22 those cells and metabolic needs of the . Okay. Either we talk about
18:26 today or we talk about it I can't remember now in your body
18:31 now, would you guys say that at rest? You guys pretty pretty
18:35 at rest? No, no All right. So what's going on
18:38 your body? Is your blood is sent all over to all these different
18:42 in your body? Alright. And this is kind of what it looks
18:45 right now and the percentages don't matter as much as you need to memorize
18:50 as into understanding the principle that we're with right now, What's happening is
18:55 blood is being sent to some They're getting more blood than they actually
19:00 . Right? So for example right your stomach is getting more blood than
19:05 needs. Right now, it's being in blood. And why is that
19:09 case? Well, because the stomach or the digestive system in general is
19:13 we refer to as a bunch of organs, Their organs that are responsible
19:19 moving nutrients from the external environment into body. And so what we want
19:25 do is we want to supply reconditioning just because just in case we might
19:31 up some extra stuff. Alright, during exercise, really what we want
19:36 do is we want to make sure muscles are really the ones getting all
19:41 fuel. Right? So we now a place where we can get extra
19:47 right? Because right now your muscles receiving just enough blood to keep them
19:53 . Right? Would you agree with ? Your muscles are not dying in
19:57 body at this very moment. She's staring at me so hard. I
20:03 I'm coming in with silly string. of these days and you're you're all
20:06 get you're all gonna get it at least the first five rows.
20:09 right? So when you begin exercising heart starts working harder. Yes.
20:17 ? You start breathing harder. your blood starts flowing faster and going
20:22 these organs and what you wanna do you want to deliver as much fuel
20:27 necessary to allow those muscles to do job that they need to do.
20:34 . And the order for that to you need to move blood from other
20:38 . But if everyone was getting all blood they needed right? I mean
20:41 limited to what they did, there no way you could shift blood
20:45 And so reconditioning organs do is it's place to send blood first and just
20:52 if you need it great if not let it pass on through. Because
20:57 I can do now is I can the use of that organ or the
21:02 that's being sent there and now move someplace else. So as I
21:05 here's your gi tract. You're getting 24% of your blood is circulating through
21:09 gi track right now. But when begin working out and running around Only
21:14 1% of your blood. Why? your gi tract doesn't need to be
21:19 stuff while you're running around. But needs work? What needs to be
21:23 stuff your muscles. So most of blood ends up in your muscles.
21:28 provides the auction the nutrients so the can do what it needs to
21:32 Now this makes a lot more sense you're being chased by a tiger.
21:36 would you want to escape the No. Yes. Okay. Just
21:41 making sure. All right. you wanna just just give it all
21:46 that's what this allows us to So, blood flow during exercises shifts
21:51 reconditioning organs to the organs of Right? So that you can do
21:57 activity is that you're That makes Okay. Now, why do I
22:02 this up? How do we go doing this? Well, this is
22:04 function of vessel constriction and dilation, we've already mentioned. Alright, So
22:10 you have this muscle, the smooth is helping to determine how blood flows
22:16 you've constrict, what you're doing is reducing the volume inside that blood
22:21 And what you're doing is you're restricting flow. You're creating resistance to
22:26 And what do we know about fluids find the path of least
22:32 Right. So, if you have blood vessels and three of them are
22:37 and one is dilated. Which way the blood gonna go to the dilated
22:42 ? Alright. And so this is of the ways that we shift blood
22:45 the body through from reconditioning organs to . Alright, so, vessel constriction
22:51 as a means to direct blood and dilation. Does the same thing.
22:56 opens it up? All right all blood vessels have a certain degree
23:00 tones so that you can go through process. Now, Generally speaking,
23:06 we hear these terms dilation results in up. So less resistance phase of
23:12 results in greater resistance. There's something that happens I'm gonna mention now that
23:18 hopefully will be apparent. You guys played with hoses when you're a
23:23 You know like turn on the water you see your brother or sister over
23:27 and what do you wanna do? wanna soak them? So what do
23:29 do? You just point the hose him? What do you do?
23:34 your thumb over the top? All , now I'm having you think about
23:38 because what did you accomplish did more come out of the hose? Know
23:44 you did was you actually included the of the fluid through that hose by
23:48 your thumb over it. But the of water that wants to pass through
23:52 vessel is exactly the same. But putting your thumb over it, you
23:58 a smaller opening. And so now same volume of fluid in order to
24:03 past your thumb has to move faster then moving faster. It creates all
24:10 velocity so that it can travel And that's why your little brother and
24:14 just got soaked. Right? So you create that resistance in a blood
24:22 , the volume of blood, you , it's creating resistance. That volume
24:26 blood still wants to pass it. what's gonna happen to the volume of
24:30 ? Is it gonna move faster or faster? And so that's one of
24:36 things if I want to get blood an organ quicker I can also vaso
24:42 my heart has to work harder to that blood through. But now that
24:46 is moving faster and when a blood dilates what happens to the speed of
24:53 blood traveling through it it slows Okay. Now this is gonna be
24:59 important here because here here's the thing we think about sympathetic activity, sympathetic
25:05 . One of the things that it and I'm going off the rails here
25:08 a second. You probably don't have write this down. You'll probably see
25:11 again on Tuesday. All right, activity acts on blood vessels in two
25:18 ways on the conducting vessels, elastic muscular. It tries to create vezo
25:26 . In fact it does. And what you're doing is you're including the
25:29 of blood. So what happens to rate it goes faster But when you
25:35 down to the capillaries and the arterials have you have different receptors and they
25:41 . So what happens there blood slows ? So why do I do
25:48 All right. The idea is I to get the blood to where it
25:50 to go fast and then when it there I wanted to do as much
25:53 as it possibly can and so I'm slow it down so that the exchange
25:57 take place and then once I leave again and goes back to the heart
26:02 quickly kinda cool. Huh? All now this is all a result of
26:09 receptors even though you have the same again, we'll probably deal with that
26:14 uh Tuesday. So we're gonna go arteries cause arteries are delivering blood to
26:24 capillaries. Capillaries are where we're going see exchange take place. Now,
26:31 we were to say should there be tunica external? Yes, there should
26:34 but there isn't one. Okay, that's why we didn't include it in
26:38 first list, you know. Does have a tunica intimacy? Yes,
26:42 cells have this indie thallium. All , well, what about the tunica
26:47 ? Well, the tunica media gets of weird and wonky. You don't
26:51 a complete or full smooth muscle. you have this dispersement of muscles.
26:57 little cells, we refer to them Perry sites, not parasites,
27:02 Perry means the next two cells. what they're called and they're a type
27:07 smooth muscle and they might be one and there might be one over
27:11 So we don't really call it a media. It's just kind of cells
27:15 are kind of hanging out. so the capillary while there should be
27:22 three layers. They've been modified to a degree that it just looks like
27:26 only have one. All right now are ridiculously small. All right.
27:35 when we're talking about the red blood will show you a picture of red
27:38 cells stacked up as a rule. , alright, so that's what that
27:42 is just basically red blood cells stacked like poker chips traveling through a
27:47 And capillaries are only as big or as big as the size of a
27:53 blood cell. So they're really, tiny and I don't know how true
27:57 is, but someone told me at point or maybe it was one of
27:59 textbooks, is that there is not cell in your body. That is
28:03 than 10 microns away from a blood . So, from a capillary.
28:08 , just to kind of put that perspective, a micron is 1/1000 of
28:14 millimeter. Okay, so, think a meter. That's about three
28:20 So, a millimeter. Is that tiny thing you had on your little
28:24 , that you never really can And so 1,000's of that every cell
28:29 your body is 10 microns away from blood vessel. A capillary.
28:39 they're kind of important because this is the cells get their nutrients from.
28:47 right, these capillaries, So they're for the material exchange between the blood
28:52 either the cells themselves or from the environment. There are three basic types
28:59 capillaries. The most common type. one that when you hear the word
29:02 . This is what you're thinking is called A continuous capillary.
29:07 And that's what you're seeing up here this corner. All right, So
29:10 do we have here basically you have layer of epithelium outside. You may
29:14 a basement membrane, you know that of serves as kind of a screen
29:19 the internal, from the from the to the external side. And the
29:25 way I can describe a capillary is these are a bunch of cells that
29:29 connected to each other by a series leaky tight junctions, which is the
29:34 weird words you'll ever hear. Right and tight. Don't go together.
29:37 the way to picture this is imagine your hands putting them together and scooping
29:41 water. Alright, So with the leak between your fingers. Yeah,
29:46 the water is really, really So it could leak. But if
29:49 like scooping up water and marbles, marbles would stay in your hand and
29:52 water would kind of drip through your . So that's kind of what a
29:56 is like. It's leaky because the between the cells are not 100%
30:02 And so very, very small things escape from the lumen to the external
30:07 and vice versa. And this is exchange is going to take place because
30:11 that very nature. Alright, So have leaky tight junctions, 95%,
30:19 the capillaries are continuous capillaries. what we can do is we can
30:27 a capillary even more leaky. And this is where you have finished
30:32 . Now, finished rated capillaries are be found in places where there's going
30:36 be a massive amount of capillary absorption capillary filtration. An example of this
30:42 be the kidney, Alright. Where moving fluid from the blood into through
30:48 filtration system so I can get materials of the blood. Alright. And
30:52 here what we've done is there's a degree of permeability and part of that
30:57 to do with and I don't have pin up here. Um I'll just
31:01 out, you can see here the dots that they try to draw
31:04 So there is a natural movement of through these vacuum als that are moving
31:11 and forth across the end of And here what we've done is we've
31:15 vacuums that are large enough that create in the cell. Alright, So
31:20 like punching holes in the cell's. now you have a way for larger
31:24 to get through the cells. So no longer depended upon the leaky
31:27 Now you have holes in the right? But they're still tiny
31:31 And so it's not gonna be like big things that are gonna pass
31:35 It's just more stuff and they're still of small. Okay, so that's
31:40 you're gonna see where these are Alright. More permeable, but not
31:46 . So and then the last one the side, you saw it,
31:49 gonna see these primarily in the liver the spleen here. What we've done
31:53 we've created Swiss cheese for the most , the connective tissue uh surrounding
31:58 The basement membrane is not complete. tight junctions are no longer tight junctions
32:03 basically big, giant gaping holes between cells, actual blood cells can actually
32:10 . And we're going to see this we talk about the spleen in the
32:12 unit, you can actually have red cells and white blood cells fall out
32:19 these sinus sides. Alright, these are really really, really leaky
32:25 . They do not limit themselves to materials. They allow everything to move
32:29 and forth. All right. So discontinuous when it comes to the basement
32:38 . So, coming back to the , because this is again like 99%
32:42 them is are like this is this kind of what a network of Kapler
32:48 look like. And over here on left hand side, this would be
32:51 arterial right. And so this is direction from which blood is coming and
32:57 it's gonna do, it's gonna pass a blood vessel that has its capillary
33:02 its nature. But because it doesn't a role in exchange, it's given
33:05 special name. It's called a meta all right. So, it's not
33:11 art artery, it's not a It's it's someplace in between. All
33:16 . And so this is where blood into a capillary bed and it passes
33:21 and becomes a thoroughfare channel on the side. Which will then open up
33:26 the smallest form of a vein which called a venue all and then you
33:30 see around like here and there, your capillary bed. So all those
33:36 around here and there. Those are actual capillaries lying between the meta arterial
33:43 the true capillaries are little tiny Alright. And these are basically smooth
33:48 cells that sit there and open and in response to chemical messages to determine
33:54 direction blood is gonna go. if this right now you can see
33:58 these vets are open or all these open. So blood is going into
34:01 capillaries and there's exchange taking place. very often you'll see when we have
34:07 of this, they showed the blood purple because you're getting rid of oxygenated
34:12 and you are receiving the oxy So that mixing makes it in
34:18 All right now they're saying, oh , no, we're going to close
34:21 those capillaries. And so now the is passing through via the meta arterial
34:27 the thoroughfare channel and going to the and no exchanges taking place there.
34:31 moving on to say another capillary Now, just to put this into
34:36 you have and again, I think from your textbook about 60,000 miles of
34:42 in your body. Pretty impressive. how long a mile is. I
34:51 , I don't know how many times the Earth that is. I think
34:54 so just you got lots of blood . We'll just put it that
34:58 Lots of capillaries. But they're so that they only account for about 5%
35:02 the blood of your body. So not very much, is it?
35:08 really, really tiny. Very very . All right. So, you
35:11 see, as I mentioned arterial is the sending blood side, the venues
35:19 the receiving side. They're not they are part of the other two
35:23 . We've looked at the thoroughfare or , the meta arterial thoroughfare kind of
35:28 as the boundary between those two. then you get those capillaries there At
35:33 given time. Only about 10% of capillaries are open. So the way
35:37 can think about this, if I my hand as an example, let's
35:40 I have five capillary beds. Can see my five capillary beds.
35:46 Right? So what happen is is is going into one capillary bed.
35:50 getting all those nutrients. And then are going wait a second. Um
35:53 need some. I'm actually starving. need oxygen and glucose. And so
35:57 one says all right, I'll close off and I'll open up this
36:00 These are remain closed and then I'll from there to this one to this
36:04 and this one and I'll just kind rotate through. And I'm now providing
36:07 and all the nutrients and all the I need. And I'm removing all
36:12 waste as I need based upon metabolic . Kind of cool. So the
36:20 that are surrounded by that capillary bed making the call, they're saying this
36:25 what I need. I'm in metabolic , provide me the nutrients and so
36:31 regulating the flow of blood at the level based on that metabolic need.
36:40 you can see how many times were and closing here. It's anywhere between
36:43 and 10 times a minute. So very often so it's just stuff going
36:46 over the place and this is referred as viso motion, you know,
36:53 blood to where it needs to All right, So we're gonna move
37:00 to the third part of our arteries, sins. We have three
37:06 levels. We go into the capillaries exchange is gonna take place. Trust
37:10 , we're gonna talk a lot more capillaries on Tuesday. We got a
37:13 to talk about players because they're the kids, right? And then now
37:19 dealing with the third part the the veins, the venus system. All
37:24 now in all of these drawings, we're doing is we're putting the arteries
37:28 the left side, we're putting all veins on the right side. Is
37:32 how the body works. Is this blood receiving side? There's a blood
37:35 side? No, your blood vessels side by side. Alright. So
37:41 you look at your wrist and you see your blood vessels, there's arteries
37:44 veins there, right there, side side next to each other. Arteries
37:48 veins always run next to one But it's just kind of an easy
37:51 to think about it because blood is put pumped by the left side of
37:57 heart. Blood is being received from systemic circulation from the right side of
38:02 heart. And so drawing a makes it easiest to understand that concept
38:07 which way blood is traveling. I do this way. Okay. But
38:12 right next to each other. So venus system is going to extend from
38:18 capillaries and they go to the And as you move from the capillaries
38:22 the heart, the blood vessels start itsy bitsy teeny tiny and they get
38:26 and bigger and bigger and bigger. so when you look at their
38:29 they're gonna tiny loom into big They're not as well defined as the
38:35 system in the artery system. We , oh we have the elastic we
38:38 the muscles, we have the arterials . We just say well there's big
38:41 in their small veins and we have als so we don't really classify them
38:47 same way because there's not so much a distinction in terms of functionality?
38:53 right? The veins are defined by size. Is it a great vein
38:58 is it a small vein that's really of how we look at it.
39:03 what we're gonna do is we're just work our way around the circle.
39:05 went from big arteries down to small , down into the capillaries. So
39:09 gonna start with the small veins and gonna work our way up to the
39:12 veins. So the smallest vein is to as a venue. All
39:17 so again, it's a cute little for a cute little tube.
39:22 what you're doing is the capillaries are up together, right joining that thoroughfare
39:29 um Channel and they that thoroughfare channel into a venue and that's where you
39:35 them. All right, They're very boring, very, very
39:39 So what they have is they have empathy liam, just like the capillaries
39:43 . And they have a couple of along with that. But as you
39:46 further and further on, you're gonna in that parasites kind of fill themselves
39:51 . They become a layer of smooth . And eventually what you'll have is
39:54 three tunics, by the time you're a venue you're still very very
39:58 But all three tunics become apparent as grow larger and larger and larger.
40:04 the interesting about thing about the veins starting with the venue. Als is
40:08 have very little tone and they produce little resistance. All right now these
40:18 companion vessels. As I said, and veins run side by side.
40:22 what you'll see is you'll see an and a venue away very close to
40:27 another. When we looked at this over here, you can see that
40:30 very, very near one another. so as a result of that,
40:34 communicate with each other very closely when arterial vessels dilate and blood is flowing
40:40 , it tells the venue I am basically I'm sending blood through this capillary
40:46 , be ready to receive it, causes the venue to respond. So
40:50 a high degree of communication that's ensuring the inflow into a capillary bed is
40:56 to the outflow from the capillary So you're not getting things backing up
41:03 , As you move on, as move from the venue of the veins
41:08 usually show all three tunics. But you'll see is that if you compare
41:13 to their companion artery that runs right right beside them, they're a lot
41:18 . All right. They don't have lot of muscle to them. What
41:22 is is that you tend to see tunica external is the layer that gets
41:26 and thicker and thicker. And the for this is because while the arteries
41:32 as a pressure of reservoir to drive forward. Vanes serve as a blood
41:39 . In other words, they are ones that are responsible for receiving and
41:42 onto blood until it's time to move forward. The way you can think
41:48 this is that they basically relax as receive blood. Hopefully this will make
41:56 in just a moment now, one the key features of of the veins
42:00 that they have valves. Arteries do have valves and the reason they have
42:04 is because they don't produce a lot pressure. It's the lowest point with
42:09 to the circulation. And so this that blood flows in one direction.
42:14 , so as we're pushing blood, passes through a valve, that pressure
42:18 the valve to open. And then that pressure stops, the valve closes
42:23 the blood tries to go back the direction and forces that blood that valve
42:26 close and these valves are very close each other, there are about 2-4
42:30 apart and they're in all your blood your veins. So what you're doing
42:34 you're seeing the incremental flow of blood from one little section to another little
42:39 of the vein as you move Now there's a lot of reasons why
42:43 do this. We'll talk about that Tuesday. But I want you to
42:46 aware of this now. Now when valve fails, it's called valvular
42:52 So here you can see a valve that's working right. But when there's
42:57 much back pressure, the valve will and it'll allow blood to flow back
43:03 the other valve. And now that , which is meant to support the
43:07 of blood between those two valves, now supporting the volume of blood between
43:13 even greater like double. I'm just up a number double. And so
43:16 valve that area expands and and sits and is sustained and expand state until
43:24 valve fails and so on, and on. And that's where you get
43:27 veins. It's a result of valvular insufficiency. So this is the effect
43:34 gravity has on the blood. Where your blood want to go in your
43:39 down to your feet? If you long enough or sit long enough,
43:42 start noticing it, right? Your start going, oh, that kind
43:45 because gravity is constantly pulling on the in your body. How do you
43:49 that from happening? I move right? And when I move around
43:54 muscles, squeeze the blood vessels and the blood through the system. It
43:59 we're gonna learn about this on All right. But if gravity is
44:05 pulling the valves are there to serve help break up the effect of gravity
44:11 of pulling all five liters of I'm only pulling a little bit of
44:15 at a time. But if I insufficiency now I'm pulling more blood and
44:20 blood and more blood and this is it looks like. Now, this
44:24 occurs in the superficial veins. The veins are within the muscles. And
44:28 time you move. Believe it or you noticed that when you sit there
44:31 I'm looking at I'm just looking at and this is what I see,
44:33 see you moving your legs, you do this a lot shaking of the
44:38 back and forth. These are things you do in perceptively, you don't
44:42 notice it, but this is part your way your body creates. You're
44:45 your skeletal muscle as a pump system massage your blood vessels. Kind of
44:50 . Right? And so that helps counter the effect of gravity.
44:55 we'll learn more about that superficial They're not deep inside the muscles.
45:00 so they're more prone to doing all fun stuff. Are we ready to
45:07 past the ugly pictures? Okay, blood as or veins is the blood
45:14 . Alright, Now we saw this a couple slides back, two or
45:19 . If you were looking carefully, saw this already, what this is
45:22 you is where your blood is in body. Alright, so again,
45:25 just separating out arteries, we're putting this side, veins are putting on
45:28 side. It's like look in pulmonary . The whole thing represents about 9%
45:33 the blood in your body, but very much right? Most of your
45:38 out here in systemic circulation. So would be 91%. And if you
45:42 is like 7% in your heart. that means the uh about 20% is
45:47 your arteries, in your capillaries. means the rest of your blood resides
45:53 the veins. And the reason it so is as blood enters into the
45:58 the vein goes oh okay I see relaxes a little bit. Alright,
46:04 dilates as a function of it receiving . And so when that happens that
46:11 you now have more volume, more so more blood hangs out in the
46:16 . It doesn't stop moving right, still moving but it's moving slowly and
46:22 slowly moving back to the heart and it's like okay then pumped and then
46:26 put in the system. But it all that time on the venus
46:30 Okay. But now the tiger jumps right, tiger chases you sympathetic system
46:38 through the roof. Does your body more blood and circulation? Where can
46:43 get it? It's right there. I gotta do is squeeze my veins
46:50 vaso constricting my veins. I'm now the space inside the veins that pushes
46:57 blood to the heart. The blood all this extra blood. What does
47:02 heart do when it receives extra It pumps it? Right frank Starling
47:07 the heart pumps what it receives and that now the heart begins working harder
47:12 faster to move that blood because that's what it does and through sympathetic
47:18 Now I'm delivering more blood to those that need that more blood to do
47:22 job that they're supposed to do. is just where we hold it.
47:26 . All right. So the reconditioning are receiving the blood. But it's
47:31 the venus side where that blood is of hanging out and it's not
47:36 it's moving, it's just moving Kind of cool. All right,
47:42 call that. Yes. Mhm. . So, I'm not sure if
48:00 hearing you. Alright, So I'm try to So with regard to the
48:05 systemic system, she's asking about the of blood. All right. So
48:09 the venus side, the movement of and we're gonna see this is what
48:12 rest of this conversation is gonna About. The rest of this lecture
48:15 about how do we move blood through body? So the movement of blood
48:19 gonna be constant because blood moves from area of high pressure to an area
48:23 low pressure. Alright, on the side we have the heart creating the
48:29 , right? And then that pressure sustained because we have these elastic arteries
48:33 so that's pushing the blood forward. on the venus side we don't have
48:37 pump, right? Our pumps up and I've just delivered blood down to
48:41 big toe, how does the blood back from my big toe back to
48:44 heart. Well, the answer to question is the heart has the least
48:49 of pressure. So its very nature I have more pressure on my big
48:54 than I have here. So, wants to go back to my heart
48:57 to overcome some stuff, but it's gonna want to do so naturally
49:02 if I want to get it there , that's when I squeeze the blood
49:05 and when I'm squeezing the blood what am I doing? I'm increasing
49:08 pressure. Right? And so it's there faster. Alright. Did I
49:13 the question? Or did I? I when it's hard for me to
49:16 , it's like, I'm just gonna to kind of guess what the question
49:19 All right. So, before we into all what I just described questions
49:27 arteries, capillaries and veins in terms their structure, which are the Yes
49:40 pulmonary that's perfectly fine. So, talked about this on like the second
49:45 of class, right? So, , systemic circulation is the the circulation
49:52 is responsible for providing your whole body all the blood that it needs.
49:57 , pulmonary circulation is. So, we're saying is that in systemic
50:02 you're receiving blood that has been oxygenated it has all the nutrients it
50:06 All right, pulmonary circulation. On other one on the other hand,
50:10 blood that has already used up its . And so what you're doing is
50:14 re oxygenating it. And so the thing you want to do before you
50:17 it off to the system is give all the oxygen it needs. And
50:20 we pump first from the right side our lungs to provide the oxygen to
50:26 blood so that we can then pump out to the rest of your
50:30 So systemic is rest your body pulmonary your lungs. Yeah, about So
50:40 gonna be internal and they're about every cm in all your blood vessels and
50:45 your veins. So just you can a Just yeah, you can just
50:50 a portion. You just look through just like there's one, there's
50:52 there's they're literally just about 2-4 cm . Alright. And what that
50:58 if you can imagine, so, have a very large blood vessel that
51:02 up the internal side of your It's a large one. It has
51:06 . But let's just say, here is. You know, that's the
51:09 vena cava, right? It's about long. And if I cut that
51:13 , you can you can see that be little valves in there and the
51:16 from here to here is about what third of a meter. Just making
51:20 a number. Right? And so can imagine it being about this big
51:24 and it has to support all that that is being pulled by gravity.
51:29 what I can do is by having valves in place, that bottom valve
51:32 supports the amount of blood from that to the next valve and that volume
51:37 blood doesn't have a lot of The next valve supports the next one
51:41 on and so forth. So what done is I've broken it up and
51:43 made it easier for the blood to because I'm no longer moving the whole
51:47 which is trying to fight gravity I'm just trying to move just that
51:51 bit up and then that next one to the next one that went up
51:53 the next one so on and so , kinda cool. Yeah.
52:04 So all right. So the question so if if you're talking about the
52:07 , right? She's saying, So you're saying if there's vessel constriction
52:11 creates greater pressure on the vessel so blood would move faster and up.
52:18 ? And so yes. And so , you can think about it like
52:21 . If I take a tube of and I squeeze on the outside.
52:25 the tuba toothpaste gonna do presuming the not on, it's gonna go out
52:29 and it goes out pretty fast. that's kind of the same thing is
52:32 squeezing when I viso constrict, I'm the muscle to contract around that vessel
52:39 it's squeezing on that vessel to propel fluid along its path of least
52:44 Now it doesn't go downward like in tube of toothpaste. If I squeeze
52:48 middle of a toothpaste tube of Some of it's gonna go down,
52:52 of it's gonna go up right. of us who are squeezed from the
52:57 of the tube know this and really hate those you squeeze in the
53:02 right? This is where we find O. C. D.
53:05 Alright. But the reason it can't down is because we have a valve
53:10 that valve prevents the backwards flow of blood. So it basically meets
53:15 That waste of the blood just wants go where there is least resistance and
53:19 where why it goes upward. Good . Anyone else I've been talking to
53:27 side of the room, this side room have questions now. Alright.
53:32 . No. Okay so there are types of pathways. We just talked
53:41 the most simple type of pathway we hey what we have when we're talking
53:46 blood vessel pathways, we have an , we have a capillary, we
53:49 a vein and then the heart is all that blood through it and that
53:52 the most simple type of pathway and of your most of the pathways in
53:56 body look like that. All And that's what you see up
53:59 you can see here, I'm look here's my arteries and I go
54:02 to the capillaries and out through the . Alright. So that's the most
54:07 type But we also have these alternative Alright. And in these pathways,
54:12 we're going to see is we're gonna more than one artery, more than
54:16 vein, or more than one Alright. And it's it's it's just
54:24 follow that normal thing. And so types of alternate pathways are referred to
54:30 , that's plural. Anastomosis is or what we may call them is
54:35 portal system. Alright. So we're gonna look at them very, very
54:39 . This is how we define them it's not hard, it's just when
54:43 see the word of anastomosis, that means there's more than one of whatever
54:47 first word tells me. Alright, if I have an arterial anastomosis,
54:53 I have is I have multiple arteries enter into a capillary system. So
54:57 two or more arteries that enter into capillary system and typically we have this
55:04 what we want to do is we to ensure that blood enters in to
55:07 capillary system. And so this is be where there's a lot of physical
55:11 or where it's very critical to get blood. So some examples up here
55:16 the joints, the abdominal organs, example, the heart, the
55:21 You're gonna want to have more than way to get blood into the capillaries
55:25 these particular things because if you don't blood to your heart, what's gonna
55:30 , you're gonna die if you don't blood to your brain, what's gonna
55:34 ? You're gonna die If you don't blood, your digestive system, what
55:38 you gonna do? You gonna be for a while then you're gonna
55:41 All right. But it all is same thing. All right. You
55:47 think about your joints right? When do this, what have I done
55:51 I've pinched blood vessels, right? , I want to have another track
55:56 which blood can actually get to the down in my hand, on my
56:01 , right? You don't want one between two points that you know there's
56:08 gonna be problems. I think of Houston traffic in Houston uh Design.
56:17 there more than one way to get the University of Houston? So if
56:22 water in your neighborhood, are you to get here? She she's like
56:27 . It got me to trap. one of my favorite ones dr
56:30 I can't come to the university There's water in my neighborhood. And
56:33 like, yeah, there's water in our neighborhoods. You know, there's
56:36 than one way to get here. . I know it's not always
56:40 but but that's the idea is that there's traffic and you need to get
56:46 or see that special someone. Are gonna find a way to make it
56:50 ? Yes, because there's always another and that's what an anastomosis does.
56:55 . So, that would be the , So the venous anastomosis where two
56:59 more veins are draining. So these very common. You see these all
57:03 over the place. So um this that blood will find its way back
57:09 the heart so that you can then oxygen to it so we can get
57:13 into circulation. Alright. We don't blood just hanging out for no
57:17 The last one is the arteriovenous anastomosis is a very very long word that
57:23 be shortened into a vascular shunt and what a vascular shunt does. It
57:27 bypasses the capillaries. So the artery directly into a vein. Alright you're
57:34 the system and the last one of portal system and the portal system is
57:39 kind of interesting. We have them some very unique places. And so
57:43 you do is the artery comes down empties into a capillary and then you
57:47 a portal vein that empties into another bed before that blood then moves back
57:52 the heart. So here you have capillaries. Alright so an example of
57:56 would be uh blood goes to your picks up or you're not your stomach
58:02 your digestive system right? Small intestines then those capillaries into into a vein
58:09 then travel up to the liver which goes through its capillary system and then
58:14 of the liver into systemic circulation all again. And what that does it
58:19 your liver to filter through the materials you brought through the digestive system and
58:25 the toxins and stuff. That would an example of a portal system.
58:29 big overt one. Alright, there others, but that's an easy one
58:34 kind of visualize. All right. those are our blood vessels. And
58:40 I wanna do is I wanna shift and I want to kind of move
58:44 Oh yes, go ahead. Uh see vascular. Oh, it's so
58:51 idea is instead of doing exchange, you're doing is you're bypassing to ensure
58:56 blood gets to another organ or or like that. I'm trying to I
59:03 there's one that I but I'm blanking it right now and I probably should
59:06 double checked before I came to but you know, lazy, so
59:12 all be perfect. All right. what I wanna do is I want
59:15 move away from these structures. I to deal with the question of
59:21 And what we're doing is we're doing gonna feel a lot like physics.
59:26 apologize for that because for those who me in A and P.
59:29 did we ever do math on a ? No, so the goal here
59:34 not to learn math equations so that have to do the formulas, what
59:39 doing is we present the equations the so that you can understand relationships.
59:44 I think this is gonna be really clear what we're gonna look at
59:47 . And what we're gonna try to is we're gonna try to understand how
59:50 blood actually flow? What is it that causes blood to move the way
59:55 does? All right. So, three things we need to first deal
59:59 . This is gonna be resistance pressure and flow, flow is dependent upon
60:05 , and resistance is alright, So is blood pressure? It's basically the
60:10 per unit area, right on a wall by the fluid in that
60:16 Right? So, last time we here, we had a bottle like
60:21 and we said inside that bottle, a fluid that fluid creates a pressure
60:27 that vessel. All right now this full. But you can see there's
60:32 in there, but that fluid is outward, trying to escape from this
60:38 that is what blood pressure is with to a vessel. You have a
60:42 , you have a fluid which is blood and it's trying to find its
60:46 outward and through that. So that that force that we're talking about
60:50 All right now, typically when we're about blood pressure, unless we say
60:54 , what we're talking about is systemic pressure. So, we're looking at
60:58 artery side and we're asking the what is the pressure on the artery
61:02 of the system? Very rarely are looking at the pressure on the venus
61:06 , unless we say this is venus . Okay, So if you hear
61:12 pressure, it's like, oh, like when you go and get your
61:15 pressure checked, what are they It's up there, systemic arterial pressure
61:23 what they're checking. They're looking at blood pressure inside your arteries to make
61:28 that they fit within the norm, is your heart having to work extra
61:33 to overcome that pressure? All right , resistance is the opposition to blood
61:42 ? Right? It's basically saying I to go that way and resistance is
61:47 we're not gonna let you. All now, this is a measure and
61:51 measured by it's a measure of the against the walls of the vessel.
61:56 , so, right now, if were to bring a skateboard in here
62:01 there's a little bit of a right? And you can imagine,
62:04 , I'm not gonna use a skateboard you started at the top of this
62:08 and you took a dive on that this carpet, how far would you
62:14 ? Not very far. Right. ? Because the carpet has a certain
62:20 of friction and when your body hits it basically grabs on and holds on
62:24 you, you can't move forward right , let's take the carpet off and
62:30 make it like the tile. If did the same thing, would you
62:36 , would you travel a distance a bit? Yeah, not very
62:41 but you'd probably slide a little bit we waxed it up, would you
62:45 a little bit further? Yeah. you could do what we did when
62:49 was in college because we had fun we took dish soap. Jolie has
62:58 me for what? Three classes Yeah. So we took dish soap
63:04 we put it on the hall of dorm and then we take a running
63:10 and we throw ourselves and see how we could slide. And imagine if
63:16 was soaked up and you took those steps and dove, how far would
63:20 go? You're looking at me like crazy. We had fun. How
63:26 do you think we could go? far? I like that answer pretty
63:32 . This is where it becomes It's like, I want to see
63:35 far. Alright now, I'm not you to go soap up the halls
63:39 the dorm room. I'm not promoting in any way, shape or
63:43 Do not sue me. Right? you see here friction prevents or resists
63:50 the movement of your body. And same thing is happening with the blood
63:55 . So the helium while it is the amount of friction, there's still
64:01 there. And so that friction prevents flow of blood. All right now
64:08 gonna be dependent on three factors which gonna deal with blood viscosity vessel length
64:12 vessel radius, but we'll deal with in just a moment. Finally,
64:15 flow, this is what we're interested , there's actually two different types of
64:18 very often you'll see blood flow, is what we're talking about. But
64:21 also see velocity of flow. Don't those two things confused. Blood flow
64:25 how many mills are moving past a per minute. So if you want
64:30 think about like this is like going to the highway and you're asking how
64:33 cars are going by per minute per time. Right? So you can
64:39 out there and you can see the zipping by at 70 miles an hour
64:42 you can sit there and count them and after a minute you say,
64:44 , I saw this many cars. that would be a that would be
64:48 . That's a volume question. Velocity of flow is how fast is
64:52 traffic moving? Well, all the are moving at roughly 70 miles an
64:57 . That's a velocity. He doesn't you how many cars, it's just
65:00 you the general speed like traffic this , what was the velocity of
65:05 Like 10 mph, 15 mph. , that's what it felt like.
65:10 no, it's raining. We've never water fall from the sky before.
65:18 . So blood flow f is dependent two different things depending on the pressure
65:25 is dependent on the radio. If have a higher degree of pressure,
65:32 other words, if there's a so if I have high pressure over
65:36 and low pressure over here, that between those two points, its
65:41 I can calculate has a direct effect the flow. Now, you know
65:45 intuitively because you're humans and you've lived . If I get on a flat
65:51 on a skateboard, do I No, Yes, no. If
65:59 put a skateboard on a flat surface I stand on the skateboard, the
66:03 doesn't move. Doesn't matter how much is there? It's not gonna go
66:07 . If I put a skateboard on slope that is one degree. Am
66:12 gonna move? If I put it a slope at 45°, am I gonna
66:20 ? AM I gonna move faster or same speed? So the steeper the
66:26 , the faster I go right, flow is directly proportional to the pressure
66:36 . So the more pressure I have over here, relative to over
66:41 the faster the flow will be Resistance is the opposite. There's an
66:48 relationship. The greater resistance, the flow I have, we can go
66:53 to the example of the carpet and and the soapy floor, right?
66:58 greater the resistance, the less flow have. So the carpet has more
67:02 . And so when I dove on carpet, I don't move right,
67:07 when I took the carpet off and down the tile, wax it up
67:10 put soap all over the top of , I moved and I kept
67:14 I went really fast. So resistance an inverse effect. The more
67:21 the less flow, the less the more flow and the last one
67:25 here demonstrates the total relationship here. I can calculate out flow if I
67:32 to. If I knew what the in pressure was, if I knew
67:36 the resistance was, I can relate to flow through. F equals delta
67:41 . Over our Now there was a who looked at resistance. His name
67:49 and he actually used those three other that resistance are made up and they
67:56 up through past uh law, which you where the radius and length and
68:04 also has this relationship through. And bunch of constants as well. So
68:09 can look at something and say, , if I know the radius of
68:13 vessel and if I increase or decrease radius, what effect does it have
68:17 the flow? If I increase or the length of a vessel, what
68:20 effective? It does it have on ? If I look at the viscosity
68:24 the fluid flowing through that vessel and change it. What effect does it
68:28 on flow as well? All of things do. And to show you
68:33 , let's just look at what resistance . Alright, we said resistance is
68:38 related. And we said that there's things. All right. The first
68:41 is radius. Alright, radius has inverse relationship. And you know
68:47 right? If you went out and a milkshake and that milkshake was
68:51 they give you a straw with What type of straw do they give
68:55 a big old fat straw? Because to suck on that milkshake into
68:59 straw, you need a big fat to allow that stuff to flow
69:04 Have you ever gotten a coffee? they give you one of those stir
69:07 ? Right? Which has like a hole. Have you ever tried to
69:11 coffee through one of those things? takes a lot of effort. Imagine
69:14 to suck a milkshake through one of straws, imagine what type of force
69:19 have to create to actually get a of milkshake to move up that straw
69:24 hard. Right? So the smaller hole, the greater the resistance.
69:31 ? The less flow you're going to right now imagine taking that big old
69:38 straw and putting it into a nice coffee. You're gonna burn every organ
69:44 your body before you even know the . All right. So, the
69:51 here says it's r to the fourth . So, what that says is
69:55 I double the radius. So if have a radius of one,
69:58 whatever. So if I have a of one unit. If I double
70:02 , then what I'm doing is I decreasing the resistance by a power of
70:09 ? Not to the to the fourth . So doubling it would be one
70:14 the sea is one of the fourth to the fourth, that's 2/16 1
70:19 . So the resistance changes 16 That makes sense. Kind of.
70:28 , if you think of the it's the easy way to think about
70:31 . Big straws, very little A little bit tiny straws, lots
70:35 resistance. Okay, length. again, you can think about this
70:44 longer the thing I have to travel the more surface I have to come
70:48 contact with that's going to have a relationship to the resistance. Right,
70:54 I push myself along the side, receiving that resistance. And so a
70:59 vessel. I wouldn't have a lot resistance for a long time. A
71:02 service. I'm gonna have a lot resistance. Lastly is viscosity, viscosity
71:09 the thickness in essence. And so I have something that's really, really
71:14 , it flows a lot easier. it doesn't it doesn't grind up or
71:20 up against things all that much. if something is thick it takes it's
71:24 for it to move. So these factors viscosity in in in terms of
71:31 many red blood cells I have. it makes the blood thicker length is
71:35 long the blood vessels are in your radius is what is the size?
71:47 , when we treat people for high pressure, we give them drugs predominantly
71:52 deal with one of these three Which factor is it? Do you
71:55 it is radius? Okay, we don't give them drugs to deal
72:02 length because the length of your blood is the length of your blood
72:05 You're not getting any bigger or smaller soon. All right, you're viscosity
72:10 change like that. But we can with is radius, right? Because
72:18 can change that in a matter of . Right? If I scare you
72:22 , you know, you're gonna you know, blood's gonna start pumping
72:27 your body. So that's something that's to manage and manipulate. But I
72:31 to point something out to you. I hope you picked it up a
72:35 of seconds ago, we talked about , we said we have 60,000 miles
72:38 capillaries in our body every time you a pound of weight, you're adding
72:45 of miles of capillaries. So you're increasing length significantly. So, what
72:52 you think would be the best way reduce blood pressure in your body to
72:57 weight, Right? Because and I'm not sitting there pointing fingers.
73:01 mean, I've got my my share blood blood blood blood vessels,
73:05 But the idea here is we're looking quick fixes with drugs like blood pressure
73:12 ? We're not dealing with the underlying , which would be length, which
73:16 be a better way to deal with term management. Alright. So
73:21 so the point here is what I to get to is when we look
73:25 plus tools law and we look at resistance is calculated. We can see
73:29 if I change the length, I'm the resistance directly. If I look
73:34 the radius, I am inversely changing . I'm making as I increase
73:39 I am decreasing resistance. And so I'm increasing radius I'm also increasing
73:46 Alright. Those are the relationships. understanding those relationships allows me to understand
73:54 relationship that you're looking at here. . And all you gotta do.
74:01 no math, right? But it's I look at this and say oh
74:05 I increase my length, what am really doing? Oh I'm decreasing my
74:11 . That kind of makes sense. . Last little bit here. I
74:17 I'm fell behind. Well we already about this blood flow is laminar.
74:23 you want to go see this, down to a bayou, look at
74:26 flow of the fluid in the in in the bayou. The water near
74:30 edges of the bayou are going slower they're rubbing up against the shore.
74:33 water in the center of the bayou moving faster because it's only resistance or
74:38 is against the the concentric ring of as you move closer to the
74:43 Alright. We talked about the flow uh being laminar in its nature.
74:48 that's what blood should look like. doesn't look like this. This is
74:52 and rarely happens in the body. there is this blood pressure gradient but
74:58 say we have the highest pressure in arteries. And so this high pressure
75:02 the arteries is our systolic pressure. is a result of the heart pumping
75:07 out into the aorta. That pressure all that volume of blood goes into
75:12 heart. Or sorry, goes into aorta causes it to expand and because
75:16 is a pressure uh reservoir, that's you're gonna see the highest pressure.
75:25 time that pressure drops over distance that drops. So you can see this
75:29 line right here represents that pressure. average of that pressure it drops and
75:34 gets smaller and smaller and smaller until get down to about zero. And
75:37 that zero is is at the vena . So you can think of your
75:43 circulation as being one big circles. create big pressure over here. Pressure
75:48 as I come all the way back and have zero pressure here. So
75:52 naturally wants it to return to the point of pressure. The lowest point
75:56 pressure is not your feet. If was all the blood would end up
75:59 and that's what you'd end up with giant bloody balloon feet. That's not
76:04 . It comes back to the heart that's the lowest point. Notice there
76:10 a difference in pressure, even in large veins relative to where the heart
76:14 the blood. It's not a very steep pressure gradient but it's still a
76:20 . So the flow of blood over is faster. Slow. It's it's
76:28 . What about over here fast? . Because we have steep gradients.
76:35 , so the blood pressure gradient serves the driving force for that flow.
76:41 right, so this is just trying show you what's going on in the
76:45 here. It's showing you the heart pumping, it pushes all the blood
76:48 into the aorta. The aorta It stretches and so now it has
76:52 forces the highest pressure in the body at that time, that high pressure
76:57 a result of the systolic activity of heart. So we call it systolic
77:01 . That's the high number. When measure blood pressure and then as the
77:07 leaves the aorta because the resistance is . Over here, basically the blood
77:12 pushed out, that pressure gets reduced , reduced and finds a low point
77:17 that's just before Sicily. Again, during dia silly of the heart,
77:21 low point of pressure is called the pressure. And so what we're gonna
77:26 is you're going to go from the point up to the high point,
77:30 going to slowly go back down that point, you're gonna go back up
77:32 the high point over and over So that's systolic over diastolic or systolic
77:37 diastolic systolic diastolic. And we go we measure that and we do so
77:41 do. So when we measure it do so indirectly. Why don't we
77:46 it directly? If I wanted to blood pressure directly, what do I
77:48 to do? I'd have to go that artery and we can do
77:53 That's what an A. Line is arterial line. They will take a
77:56 giant needle, they'll stick it into carotid artery and it has a little
78:00 on it and they can measure your pressure. Anyone want to do that
78:02 you go visit the doctor. Okay good. So what we do
78:06 we use something different, we use fingerprint a blood pressure cuff. I
78:13 the word. I think that should be the test. If you can
78:16 this, you pass meter. There go. Alright and what we're doing
78:25 we're basically squeezing on an artery so is flowing through it just normally.
78:30 what we're gonna do is we're gonna on it until we include the flow
78:33 blood. And then what we're gonna is we're gonna listen for the sound
78:37 remember blood flowing through a blood vessel no sound right? It's only when
78:41 interrupted. And so the sound we're for something called a Korolkov sound.
78:46 what you do is you create here can see here's the pressure going up
78:49 down up and down. What we is we create enough pressure so that
78:52 include the flow of blood. And we'll reduce or release the pressure.
78:56 then we start listening. And when can hear your first sound, that's
79:00 sound where the pressure inside the vessel greater than the pressure outside the
79:03 So it makes a sound. So your systolic pressure. And then you
79:08 hearing. Sh push push push push . As the pressure keeps decreasing until
79:15 hear no sound. Now you've reached point where you found the low point
79:20 the pressure. So the pressure inside vessel is so big that it has
79:24 resistance. That would be your So what we do is we express
79:30 in a value. Usually the perfect is as we said, 1
79:34 Systolic would be 1 20. Diastolic be 80. Last slide. And
79:40 we're done All right now, these pressures are what we're most familiar
79:47 But the body doesn't care about systolic diastolic. Alright. We physiologists
79:53 well let's do some math. Let's some stuff out. We have something
79:56 called a pulse pressure. That's the between the systolic and the diastolic.
80:00 the pulse pressure would be if it's 20/80 it would be 1 20 minus
80:04 . So pulse pressure. Is that right? It's the difference between
80:10 All right? I'm trying to make . Yeah. So the pulse pressure
80:14 be 40 in a healthy human. ? But if my systolic 1 60
80:19 diastolic was 1 20. What's my pressure? Has it changed?
80:24 No. So, there's something nobody cares about. And this is really
80:28 mean arterial pressure. And again, kind of did some math and figure
80:31 out. And basically says, this is your average pressure driving things
80:35 . It's roughly equivalent to your Diastolic is what, 80?
80:41 And it's a third of your post . What's your post pressure? 40
80:45 by three is And they have got make you guys start memorizing these math
80:51 . My kids can't do math in heads like this. Alright. 40
80:55 by 13 divided by three is 13.3 . Right. Yeah, I like
81:03 . Alright, so 80 plus 13.333 93. Thank you, 93.
81:10 so it's 93 is what we're looking is an average. That's what your
81:14 is trying to maintain and it really a function of your cardiac output.
81:21 . The further you get from the , the lower your pulse pressure and
81:26 mean arterial pressure become And if your is decreased what happens to the
81:34 it slows down. That's what we're for. So, that's where we're
81:37 start on Tuesday we're going to then and see what our body does with
81:42 this fun
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