Hepatic Circulatory System (Nursing)

00:00 Hi, welcome to our video series on the liver. We're going to take a closer look at the hepatic circulatory system. Now, first let's start with a question. Do you know how many blood supplies the liver has? Well, unlike any other organ, the liver has 2 major sources of blood supply. If you take a look at the liver there, you see those 2 big blood vessels behind it. Now, the red one is right off the thoracic aorta. Now, that's a branch coming right off the left ventricle.

00:31 You've got the major aorta, it travels down through your body. Off of the thoracic aorta, you've got the hepatic arteries that supply the liver with fresh oxygenated blood; however, you've also got the portal vein. Now, the portal vein supplies 75% of the blood that rips through the liver comes from the portal vein. Now that's also venous blood because it's returning from the guts, from the intestines. So, the liver, unlike any other organ, has 2 major sources of blood supply. So we talked about the giant red aortic vessel behind the liver, now let's move over and look at the blue vessel. That represents the vein. So, we have a superior and an inferior vena cava, but what's the difference? Let's take a look at it. So take a look at the drawing there. So we know that the vena cava is the largest vein in your body, and it carries deoxygenated blood back to the right atrium of the heart. Now, the inferior vena cava carries blood from the lower part of the body, inferior meaning lower. The superior vena cava carries the blood from the head, arms, and the upper body. So, that's the only difference between the superior and the inferior vena cava. It just describes the parts of the body that it brings deoxygenated blood from, inferior from the lower, super from the upper part of the body. So, we've made a very simple drawing for you to kind of understand the direction of blood when it comes to the liver. We know the liver has 2 blood supplies, the aorta, so look at the right side of that drawing. Now you see the liver in the middle. You've got the right lobe, a little bit larger than the left lobe, and it's divided by the ligament in the middle. You see that it's connected to the gallbladder there. Alright, so we're oriented. Look on the right side of the screen. Now we've just pulled those vessels apart to kind of make it easier for you to understand. That's the aorta. That's coming from your left ventricle through the main part of your body, off of the aorta, the thoracic aorta specifically. The hepatic artery branches off, and that's what brings oxygen-rich blood to the liver. Okay, now the other supply is the hepatic portal vein. Now, that's nutrient-rich blood because look it's coming up into the liver from the gastrointestinal tract, so you have your colon, your small intestine, and all that going on, that's all dumped into the portal vein. Now that's 75% of the blood that is flowing through your liver. So, you see the 2 blood supplies there, artery, oxygenated blood, portal vein coming up from the gut and that's bringing all the substances back to the liver to be processed. Now, after it runs around in the liver, it's going to exit the liver via the hepatic vein. It's going to drain into the inferior vena cava and go back up to the right atrium. That's it. That's simplifying the blood supply of the liver. Now, this portal vein system gets a little involved, so we want you to have a really good picture to see what it looks like. You see you've got the intestines there and all these blue vessels. Right? You've got an inferior mesenteric vein. You've got a superior mesenteric vein. So you've got all these veins coming together. You've got a splenic vein. They all come together. Where? Right, at the portal vein. So, it's this network of blood vessels, and they bring blood from the intestine, the stomach, the spleen, and the pancreas, and it all meets and drains together in the portal vein, and that is the blood supply, 75% of the total blood supply to the liver.