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Anatomy of the heart

Dr Sam Boateng, from the University of Reading, explains the anatomy of the heart, looking at the atria, ventricles, blood vessels and valves.
Hello, I’m Doctor Sam Boateng. And today I’m going to talk you through the anatomy of the heart. The human heart is about 300 grammes in weight and about the size of a fist.
So although the heart pumps as a single unit, actually consists of four mini pumps, or full small chambers that work together as a functional unit. The heart has two atria at the top, and two ventricles at the bottom.
It’s important to note that the walls of the atria are considerably thinner than those of the ventricles, and that’s because the atria pump blood at a much lower pressure. The ventricles on the other hand, pump blood out of the heart on the right side to the pulmonary circulation whilst on the left side, blood is pumped out of the heart to the systemic circulation.
The atria and the ventricles are separated by atrioventricular valves that encourage uni-directional flow from the atria to the ventricles. They also prevent blood from returning back into the atria when the ventricles contract. There are a number of papillary muscles that are associated with the atrioventricular valves, and these contract when the ventricles contract. They pull down when the ventricles contract. And these prevent blood from returning from the ventricle back into the atria.
Now in addition to the features that we’ve discussed previously, there are four large vessels that bring blood into and out of the heart. On the right side we have the vena cava that brings in deoxygenated blood from the systemic circulation into the right atrium. This is then pumped out of the heart through the pulmonary artery to the pulmonary circulation and ultimately to the lungs, where the blood is re oxygenated. This returns back to the left side of the heart through the pulmonary vein where blood returns to the left atrium. This is then pumped out of the left side of the heart, the left ventricle, through the aorta. And this pumps oxygenated blood to the systemic circulation.
Now in addition to the atrioventricular valves that separate the atria from the ventricles, there are also two semilunar valves located in the arteries, the two large arteries in the heart. So on the right side we have the pulmonary valve that separates the right ventricle from the pulmonary circulation. And on the left side we have the aortic valve that separates the left ventricle from the systemic circulation. And these have a similar function in preventing blood from returning back into the heart after the ventricles contract. Now the heart also has a number of large vessels that supply the heart with oxygen and nutrients. These are called the coronary vessels.
The coronary arteries supply oxygenated blood to the heart and the coronary veins take deoxygenated blood away from the heart. And it is these coronary arteries that can become diseased. When there is coronary artery disease, these can become blocked. And this can prevent oxygen and nutrients from reaching the heart. And these can result in heart attacks.

The heart consists of four pumps that work together to circulate blood around the body. In this video, Dr Sam Boateng describes the anatomy of the heart, looking at the atria, ventricles, blood vessels and valves.

You can download the Week 1 supplement, which contains additional images and descriptions to help you understand the topics covered in this video.

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