 Hi, everybody. Today we're going to start our three lecture series on the cardiovascular system. We're going to begin cardiovascular land with a conversation about blood. Blood is the fluid that is pumped through the body. Other aspects of the cardiovascular system include the heart. As you can see, I've drawn you a lovely heart here. I'm going to expand on this heart today to show you kind of a big picture of what is the cardiovascular system. And then similar to the way we've treated other topics in this course, we're going to fill in details over the next three days. So let's start thinking about the heart as a pump for fluid or blood. And if you're going to be a pump for fluid, then there essentially has to be something you're pumping around and what you're pumping is blood. This is my image of the heart in typical Wendy style. It's a little bit diagrammatic. Your heart doesn't exactly look like this, although mine is very close. I'm drawing the diagrammatic heart because there is no way on the planet that I could draw an anatomically correct heart. But I'm going to draw my diagrammatic version in typical Wendy style with anatomically correct details. So getting comfortable with the diagrammatic version often will help you interpret the actual heart when you get there. In my class, we are going to play with sheep hearts. So you're actually going to have the chance to do your own heart dissection, which is pretty interesting and helpful in figuring out how hearts work. That's the topic of our entire next lecture. I just don't want you to get distracted by the fact that, oh, I drew a lovely little heart in the middle of my page. But look, your heart is actually two pumps stuck together, a right pump and a left pump. And remember that we're looking down at our patient, the right is on this side, this isn't a windy-ism, oops, I switched my right and my left, no, it's actually my patient's right side and my patient's left side. So what you're going to notice in my heart, there are four chambers. And I'm drawing them this way on purpose because this will help us kind of visualize the anatomy a little bit better. I've drawn, you can see my four chambers now, these little, I don't know, V structures, these are valves. These are one-way valves that allow blood to flow between the chambers. Now, there are two places, we have two pumps to our heart and there are two places that you're going to send blood. First of all, doggies, you better be cool with the fact that we've got to send our blood to the lungs. We've got to send our blood to the lungs at some stage in the game. You've got to send your blood to your lungs. Why? Well, we need to get oxygen in our blood. And blood before it goes to the lungs is, I don't know, I think of it as dirty blood because it's full of carbon dioxide which was produced through cellular respiration, metabolism of your cells. One of the byproducts is carbon dioxide. And so we've got to get rid of that carbon dioxide. We also have to load up on oxygen which is a requirement for cellular metabolism as you all know. So, not only do we have to go to the lungs and load up on oxygen, but we also, our little pathway here, ultimately, why are we loading up on oxygen? Well, it's because we need to go to the body. And when I say we're going to the body, I guarantee you we're going to get a little more specific than that in this class. However, for today, it's helpful to kind of see the big picture. So I'm going to show you how our heart, how the vessels are structured in our heart. First of all, the right side of the heart is dealing in, I don't know, I call it dirty blood. The right side of the heart takes deoxygenated blood from the body and brings it in to the heart. And it travels through the ventricles, through the two chambers of the heart, and then it heads out into the lungs. So look at what happened here. And then into the lungs. Do you see that? So I've got blood flowing from the body. It's been all used up. And it flows through the right side of the heart and it travels to the lungs. I also have, once it goes through the lungs, tell me about the blood. Is it dirty blood anymore? No, we are no longer dealing with dirty blood. Why am I having a hard time picking a red? There. I want it to be red because I want to show that it is happy, clean, healthy blood. And now we got to go back to the heart and we go back to this chamber and you'll notice the blood will come into the heart. It will travel into the second chamber and then look at what happens. This is actually pretty cool. It gets pumped out of the second chamber on the left side. And this is, you know, some of these details are actually accurate and the blood is going to be pumped out and fresh, lovely blood is going to head to the body. This is my overview. Now, today we're going to look at several pieces. For example, I really want to look at these blood vessels. We have multiple flavors of blood vessels. Blood vessels that carry blood away from the heart are arteries. I remember this because arteries starts with an A and so does away. So arteries are carrying blood away from the heart. Most arteries, but not all, are carrying freshly oxygenated blood. Do you see an artery on this picture that is carrying dirty blood? That's an artery. Blood is being pumped away from the heart. So that is also an artery and it's carrying dirty blood. So the key with arteries is that they carry blood away from the heart. You also have veins. Vains carry blood to the heart and so these guys are veins. Vain is a vein that's carrying oxygenated blood toward the heart from the lungs. Most veins carry deoxygenated blood. You probably are thinking what is in the middle like this purple zone because you know I'm totally color coded and the purple zone primarily consists of capillaries and capillaries are tiny, tiny, tiny little blood vessels like literally one red blood cell can travel through a capillary at a time. Like these things are tiny and they're found in the... basically in the places where we're going to do any kind of exchange. So if we're going to carry the blood to the cells we need to have a capillary where we can exchange substances. Cells metabolize. They're metabolized. They're doing stuff. They're super active. Like whoa, how fun is that? And while they're metabolizing they're producing garbage and in order to metabolize they need resources and energy. So blood is going to help us do all that. Let's look. We've got these three main kinds of vessels. So let's look at the more detailed anatomy of those vessels and then we'll dive into what is carried in those vessels.