We will have all this anatomy in lab, so you might have had it already, or might not. So it may be a review, or it may be brand new. But our heart is actually two pumps. I was stupid.
When I learned this, and somebody explained to me how blood flow worked, it didn't make any sense at all. Because in my head, I thought the heart pumped and shipped blood, and then it pumped. and shipped blood. I didn't think of it that each side of the heart was actually an independent pump. But the path anatomically is very similar.
We're starting on whether you're on the left or right side. We're starting with the atria. We have to go through an atrioventricular valve, which is a valve between the atria and the ventricle. They have other names, of course, into the ventricles and then out the semilunar valves.
So the atria, those are those smaller upper chambers in the heart. The AV valves, now remember in lab, you need to call them right or left AV valve if you want to use AV valve. Otherwise, on the left side is the bicuspid valve, and on the right side is the tricuspid valve. The bicuspid valve is also called the mitral valve.
So isn't anatomy super fun? So remember in lab, you're writing these out. In lecture, I try to put all of the multiple answers, but if I forget, you can always ask me, Hey, can I also? is this also called the mitral valve?
And I would say yes, because there are so many names for the same thing. So as we go through the AV valves, then we go into the ventricles, which are the larger inferior chambers of the heart. And then we either shoot out the aorta or the pulmonary trunk through the semilunar valves, which are also just called the pulmonary and aortic valves, or you can call them pulmonary semilunar valve and aortic semilunar valve.
Sorry. I wish someone had shown me this picture, because I think I would have been a lot less confused about the dual pump. So the ultimate goal here is to make sure that we separate clean blood from dirty blood.
That we separate that beautiful blood that's full of oxygen. and low in carbon dioxide, we separate that from the blood that's very low in oxygen and high in carbon dioxide. So I always say this is like kind of similar to making sure that your water line and your sewer line are separate in your house.
We don't want any mixing. So the right side, shown here in blue, is all about getting things to the lungs. So remember, the right side collects, or if you haven't had it in lab yet, the right side collects all of the dirty blood from the entire body. So it's got to ship that blood to the lungs, so that way it can get rid of all the carbon dioxide and pick up more oxygen.
So we call the right side the pulmonary circuit, and we call the left side the systemic circuit, because the left side, pictured here in red, is to illustrate oxygenated blood that needs to be shipped to the entire body. body. So every cell in your body is waiting for that oxygen that the left side is going to deliver.
So we call it the systemic circuit because it's going to all of your body's systems. The only problem I have with this picture is something I've said in lab, blood is never blue. So anytime you see blue, what they're trying to show us is oxygen poor.
But some people think or have learned at some point that blood is blue until oxygen touches it. and that's not true. Blood is two colors. It's either bright red, which means oxygen, or dark red, which means low in oxygen.
If you've ever watched the nurse draw the blood out of your arm, it's not blue. It's dark, dark red. So the major vessels that are going to bring things to and from and back and forth to the heart, the first one, the superior vena cava, which is shown here.
So this is one of the largest veins in the body. You can see it's above the heart. And this is collecting all of the dirty blood from your head and shoulders.
So this is bringing everything kind of superior to the diaphragm, from your head, your neck, your shoulders, your arms. So all of the deoxygenated blood. The inferior vena cava is collecting everything south of the diaphragm.
So everything from your abdomen and your legs and your toes. So it's bringing everything from south. So, again, a very, very large vein. This is something else I never thought about. Besides the heart being two pumps, I was stupid and I just thought, okay, the heart pumps blood.
I never thought about the heart needing blood for itself. And so the heart feeds itself, of course. That muscle tissue especially has to have that oxygen. oxygen. And so the blood that is deoxygenated has to collect somewhere.
So in this picture here, you can see the coronary sinus. So this is a major vein that's on the backside of the heart that has collected all of the dirty blood from the heart itself. So heart valves.
Heart valves are a way to keep the blood flowing. So heart valves are like doors. After a concert, especially when everybody's rushing to their cars, You want to make sure everybody's going in the same direction because you don't want traffic to slow down.
Well, in this case, we want to make sure blood doesn't slow down. We have a minute for blood to go from the heart to your body and back to the heart. We have cells that are waiting on that good stuff and waiting for their trash to be picked up, and they will die without those things.
So we need to make sure everything's flowing in the right direction. So we have the right and left AV valves, which you can call them that, or the tricuspid, bicuspid, mitral valves, other answers. So these guys have the same structure.
If you remember from lab or you will be seeing in lab, they look like little parachutes. The chordae tendineae are the little strings that make sure that kind of like you don't want your parachute to invert. You don't want to plummet to your death.
We want to make sure these valves stay flowing in the right direction. Those chordae tendineae are attached to the papillary muscle. Papillary means finger-like projection.
So these are like little fingers that come out of the heart wall and grab those tendon cords. Mitral valve prolapse. we want to make sure that this valve doesn't, like, invert.
And so especially on the left side, which is the mitral valve or the bicuspid, that would be incredibly dangerous. Because remember, the left side of the heart is that oxygenated blood. And so we've got cells that will die in just a few minutes without that blood, so we don't have time for that valve to behave badly. The semilunar valves, remember, you can take out for lab the word semilunar.
The pulmonary valve and the aortic valve, pulmonary valves in the pulmonary trunk, and the aortic valve is in the left ventricle. And we also have conditions we call murmurs, which is when the valves are leaky. So I always think it's kind of like a door, how you'll have a space under a door where air can still get through, or stenotic, where the valve is very narrow. Usually a heart murmur is not too big of a deal because it's just you're losing a little bit of blood.
It's not closing completely. It's not usually life-threatening. So the anatomy, we will be having in lab.
You've probably had this already, but if you haven't, I'll have this exact picture up in lab. So just to kind of review some of the major things, if you look there, the superior vena cava and the inferior vena cava are those large veins that are returning. everything to the right atria.
Because remember, it's his right, not your right, which I know can be confusing. So the right atria is collecting all of the dirty blood from the entire body, including the back of the heart. So that coronary sinus is going to drain into the right atria as well. So the blood goes from the right atria to the right ventricle through the right AV valve or tricuspid valve.
Then it's going to shoot out that pulmonary trunk. I always think of the pulmonary trunk like a tree trunk, how you have the trunk and then it branches. The pulmonary trunk is going to branch into the left and right pulmonary artery. So here's the exception to the color rule. Anytime in lab, when you see blue, it means vein.
Red means artery, except for around the heart. Blue, remember, is there to denote low in oxygen. So the pulmonary artery is moving blood away. A and away, that always works.
Arteries always move blood away from the heart. So this blood is moving away from the heart to the lungs because of the word pulmonary. Well, why would I go to the lungs if I already had plenty of oxygen? So this guy is going to go to the lungs.
lungs, he's low in oxygen. That's why he's going there, which is what makes him an artery because he's A away. He's leaving the heart.
So then we're in the lungs. We pick up all that oxygen, get rid of that carbon dioxide, and now we're going to come back to the heart. So since we're coming back to the heart, it's a vein because A and away. Artery is away. Veins towards the heart.
Pulmonary because we're coming from the lungs. So these guys, if you look, are bright red. This is the best blood in your whole body.
This guy has the most oxygen of any blood in your body. It's just been. been to the lungs and picked it up. So when it dumps into the left atrium, that's the best blood there is. So the blood moves from the left atria to the left ventricle.
We again go through the left AV valve or the bicuspid valve or the mitral valve into the left ventricle. And then we shoot out the aorta through the aortic valve, which is that little valve that's tucked in there. So the semilunar valves, you don't have to say the word semilunar, but if you look at the pulmonary valve and the aortic valve, they look like little moons.
So that's why they call them that. that. So the left side, another thing to notice, is how thick that muscle layer, the myocardium, is on the left side. That's because the left side has to squeeze, right?
Like really powerful if it's going to get to your entire body. Think of the force needed for the blood to fight gravity to get to your brain and then also needed to get to your toes. So most of the other details of the anatomy we'll be covering in lab, but I just put this picture in here so we could review it.
What I want you to appreciate from this picture is, in lab I will reference this as well, that if I give you a cow heart on the lab practical and open it up, you should immediately be able to tell left from right. Look at how thick and beastly that left side myochondria is. That's crazy.
But again, we need the left side to be so muscular because it has to squeeze the blood to the entire body. If you look at the heart valve picture there, it's really showing those chordae tendineae. which are there to just make sure we anchor those heart valves because we do not have time for that door to swing the other way.
We do not have time for blood to back pool in the heart. You will never have to write out the flow of blood through the heart, but it is good to know. It helps with the anatomy and it helps with the physiology.
So the superior and inferior vena cava are bringing blood back from the entire body. The superior from your head and shoulders and your arms, the inferior... from your knees and toes and everywhere else from south of the diaphragm.
But then we also have that coronary sinus, remember? The heart has dirty blood also because the heart fed itself. So all three of those blood vessels are draining into the right atria. The right atria collects all of the blood vessels.
of the dirty blood. Then the blood goes through the tricuspid valve or the right AV valve into the right ventricle, out the pulmonary trunk through the pulmonary semilunar valve or just pulmonary valve into the pulmonary artery. We go to the lungs, we pick stuff up, we come back through the pulmonary veins.
We then dump all that beautiful good oxygenated blood into the left atria. We go through the left AV valve or bicuspid valve or mitral valve into the left ventricle and then out the aorta through the aorta. semilunar valve, or just aortic valve, into the ascending aorta. So you want to be comfortable with the flow chart of that.
It helps with the anatomy. This picture I just included so you could practice. Some people like to draw the blood flow through the heart on an actual diagram.
I just wanted you to have one. So if you notice in that picture, there are three large arteries from the aortic arch. The brachiocephalic artery, the carotid artery, and the subclavian artery.
So we call this BCS. That's not a word, but that's just how I remember it. Anytime I look at it, I remember it.
look at a heart model, I just go BCS. So brachio means arm, cephalic means head, carotid artery, you can feel in your neck, you can feel your pulse, and subclavian, sub means below, and clavian comes from clavicle. So these are the three branches.
coming off the aorta that are going to feed your head and your arms and your shoulders. So the brain gets some of the best blood in the body, which makes sense, right? The remainder of the blood then has to feed the rest of your body.
So that's going to go down the descending aorta. Above the diaphragm, in the chest, we call it the thoracic aorta. Below the diaphragm, we call it the abdominal aorta. So this is one of the frustrations with arteries and veins.
It's very similar to last semester with nerves, where you'd be cruising, it's a nerve, you'd be cruising, and then it forks and its name changes. So it's the same thing with blood. It's like a road.
You're on Main Street. All of a sudden, it becomes Route 1. So it's just, it's the same tube, but its name changes based on where you are in the body. So the aorta is the largest artery. It branches off to other arteries, smaller arteries, arterioles, capillaries, veins.
larger veins, and then back to those vena cavas. So it's a big loop. There is one word we need to add here that I made a mistake. Between capillary exchange and veins, we need to add venules, V-E-N-U-L-E. This is fixed on other slides when we really get into the detail of this.
So right now, the detail of this blood flow is not that important. We'll be getting there.