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Question Video: Recalling the Names of Valves in the Heart Biology

Pulmonary arteries and the aorta are major blood vessels that carry blood away from the heart. There are valves at the bases of these vessels to prevent the backflow of blood into the ventricles. What is the name of these valves?

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Video Transcript

Pulmonary arteries and the aorta are major blood vessels that carry blood away from the heart. There are valves at the bases of these vessels to prevent the backflow of blood into the ventricles. What is the name of these valves? (A) Semilunar valves, (B) bicuspid valves, (C) atrioventricular valves, or (D) ileocecal valves.

To answer this question, let’s have a look at the structures of the heart and some key facts about the circulatory system in general. The heart is a muscular organ that is responsible for pumping blood all around the body. One of the jobs of the blood is to deliver oxygen and nutrients to the cells, and it is vital these are delivered rapidly enough to supply the needs of the cells. The heart and the rest of the circulatory system are therefore designed to move the blood around the body as efficiently as possible. The blood flows around the body in one direction: from the heart, through arteries and capillaries, and then back to the heart through veins.

If you look at the diagram, you can see the labels numbered one and two. These refer to the right and left atria, respectively. Atria is the plural. Atrium is the singular. These are chambers at the top of the heart that receive blood coming back to the heart via the veins. The left atrium receives oxygenated blood from the lungs, and the right atrium receives deoxygenated blood from the body. Blood is then pumped from the atria into the ventricles. The right ventricle is labeled as three, and the left ventricle is labeled as four in this diagram. As explained in the question, the blood will then leave the heart through the pulmonary arteries, which carry blood from the right ventricle to the lungs, and the aorta, which carries the blood from the left ventricle to the body.

We mentioned earlier that the blood flows in one direction. The heart has structures to make sure this happens efficiently. So, when the heart contracts, the blood should flow out of the arteries only and not back into the atria. And when the heart relaxes, the blood which is in the arteries should not flow back into the heart. This prevention of backflow of the blood happens thanks to structures called valves. The semilunar valves are moon-shaped valves found at the bottom of the arteries leaving the heart. Semi- means half, and lunar means moon. These prevent the backflow of blood from the pulmonary arteries and aorta into the heart.

Then there is the bicuspid valve, situated between the left atrium and ventricle. Bi- means two, and cuspid refers to a pointed tooth. So this valve has two pointed flaps. The tricuspid valve is located between the right atrium and ventricle, tri- meaning three, so this has three flaps. Both the bicuspid and tricuspid valves can also be called atrioventricular valves as they separate the atria and ventricles. The flaps of the bicuspid and tricuspid valves attach to tendons. This is to make sure they only open downwards to the ventricles and they cannot turn inside out by mistake. Therefore, the blood always flows from the atria to the ventricles.

We can now answer the question. The structures within the heart that control blood flow from the pulmonary arteries and the aorta into the ventricles are named in answer choice (A), the semilunar valves.

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