 Hello, my little cute hearts. So today we get to capitalize on all the cardiovascular stuff that we've done so far. We've talked about blood. We've talked about vessels in general. We know all the different kinds of vessels that we have. And we've talked about the heart in detail. We know all of our heart structures, and we also know the great vessels that are coming in and out of the heart. Today we're going to fill in the vessel pathways or highways that will take blood to every single part of your body so that you can have gas and nutrient and waste exchange in the organs and in the tissues. And every single cell in your body needs to be within range of a bloodstream so that that exchange of nutrients and garbage can take place. If cells don't have that, they die, which is why when your heart stops beating, you're kind of a done deal because your cells need your heart. Okay, so don't let your heart stop beating. And instead, let's look at some pathways. Before we begin looking at all the anatomy to get us to various locations, we need to do a review of the heart. And there's a little bit of new stuff that I want to bring in. Arbitrarily choosing to begin this conversation in the left atrium of my heart. And you can see that I have actually four vessels. You can't see the other one, but here they are. You can't see where they enter into the, where they dump materials into the left atrium. But these are my pulmonary veins. You already know them. And they're bringing blood, fresh oxygenated, yummy blood from whom? From the lungs. This is the left lung, okay? And look, this is the right lung, sure. And the right and left lungs deliver that blood. That's actually a capillary bed in the lungs. The blood comes back to the heart through the pulmonary veins. We're cool with that. Once the blood is in the left atrium, it passes through who? My left AV valve into the left ventricle. Once the blood is in the left ventricle, it passes through the who? Who is that little valve? Because we're from the left side. That is actually my aortic semi-lunar valve. And we pass through the, from the left ventricle into who remembers? Go ahead and shout it out. Into the ascending aorta. And that's as far as we went with, we said the ascending aorta was our great vessel that leaves the heart with fresh blood. And where is this blood vessel going? It's going to the body. We're going to get a little more specific now. The ascending aorta is the part of this big arch that is going upward. It's ascending. It turns into the aortic arch. Now, take a deep breath and accept the fact that this is a circulatory system. Often there is an anatomical structural location where a vessel changes its name. But look at this. It's a tube. And the ascending aorta is the same tube as the aortic arch. It's just in a different location. And really you could argue that all your vessels are all one highly branched, crazy tube. So, be okay with that. And you, the ascending aorta goes up. The arch makes an arch. Just because we might as well look at what comes next, what do you think this part of the aorta is called? And I'm going to give you a hint because I'm going to finish this aorta. Look where my pen is. I'm traveling down, traveling down, traveling down. The vessel actually travels behind the heart, but it's continuous from this guy right up here. Who's that? All right, I got to go back to green, right? We'll call it right here. That's, I mean, it starts right here. And it's headed down and it continues right here. Guess who that is? That is my descending thoracic aorta. Descending aorta, aortic arch. Descending thoracic aorta. How long do you think it's called the descending thoracic aorta? As long as it's in the thoracic cavity. Nice. Okay, well, the other thing, not all blood vessels go to the descending thoracic aorta. Excuse me, not all blood cells are going to go through the descending aortic thoracic, whatever I just said. What I'm trying to tell you is that there are branches coming off the aortic arch that I want to take the time to name right now. As an example, this is new, but as an example of the fact that we're going to go multiple places. The first branch, think about your blood coming up through the ascending aorta, the first branch to the right side of the heart is the brachiosephalic artery. Brachiosephalic artery. The brachiosephalic artery is the one artery that we are not going to specify as coming from the right or the left side because there's only one. There's not a right brachiosephalic, even though brachiosephalic artery travels to the right side. We don't have a left brachiosephalic artery. And you will, when we start talking about blood flow to the upper limb, which I think is our next topic, you will see some, like, some nuances of the brachiosephalic artery that make it a little more clear. My middle branch, if the blood cell is like, dude, I'm not going to the arm or the head on the right side of the body. I want to go somewhere else. I want to go to the head on the left side of the body. Well, in that case, they're going to take this little off-ramp, which is the middle off-ramp off of my aortic arch. And that is the left common carotid artery. And that goes to the head. You've got a whole section of talking about the head. If the blood vessel cell is like, hedge, med, I want to go to the left arm. Then we're going to take a different vessel. We're going to take the left subclavian artery. Those are our three branches off of the aortic arch. So take a look at this. From the ascending aorta, we can travel to the brachiosophallic artery and go to right side arm and head. We could go through the left common carotid and go to the left side head. We could go through the left subclavian and go to the left side arm. That's my right side. Over there is my left side. Or we could stay in the aorta and travel through the descending thoracic aorta and then choose your own adventure. We're going to have lots of options there. At any point, we could say, okay, this vessel feeds whom? And you can come up with the structures or tissues that are fed by each of these vessels. Choose your own adventure. That's the topic of this lecture. But once we get there and we work through a capillary bed somewhere in the body, somewhere along here, we're going to work through a capillary bed and now our blood exchange has happened and now we have dirty blood. We got to get back to the heart. We have two routes. If we went down the descending thoracic aorta, most likely we're going to come back. In fact, I say most likely, but I think 100% of the time. We're going to come back in the inferior vena cava. We've seen this guy before. Different named veins will dump into the inferior vena cava, which will come back to the right atrium. If you're draining blood from the head or the arms, then you're going to come in through the superior vena cava and both of them dump into the right atrium. Blood from the right atrium flows through the right AV valve and up through into the left ventricle, right ventricle, and up through the pulmonary semilunar valves and into the pulmonary trunk. We know this guy already. And the pulmonary trunk branches into my pulmonary arteries, which head to the lungs. Did you follow all that? You already know all of that. That's all review. So now let's flesh out the stuff that's going to happen to feed various parts of the system. Okay, so we're going to start feeding the upper limb. The upper limb is one of the more complicated pieces, probably because of our friend the brachiosophallic artery, which makes it non-symmetrical. Take a deep breath, get yourself some chocolate, and let's come back and talk about the upper limb.