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Question Video: Explaining Why Veins Often Contain Valves Biology

Why do veins often contain valves?

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Video Transcript

Why do veins often contain valves? (A) To keep blood moving at a high pressure. (B) To ensure that blood is able to clot properly. (C) To prevent blood from becoming deoxygenated. (D) To prevent the backflow of blood. Or (E) to keep blood moving against the concentration gradient.

In your body, blood is pumped by the heart and circulated through a network of blood vessels, which form the circulatory system. The flow of blood delivers molecules like oxygen and nutrients to the organs of your body and carries away the waste products they generate. This helps every organ in your body function normally, keeping you healthy. The circulatory system is described as a closed loop. This means that blood flows in a closed circuit from the heart to the various organs of the body and back to the heart. Arteries are the blood vessels that carry blood away from the heart, while veins are responsible for carrying blood away from the organs and back towards the heart.

It is extremely important that as blood flows around the body, its direction does not reverse. In arteries, the pumping pressure of the heart prevents blood from flowing in the wrong direction. Veins, however, are further away from the heart, which means they have lower blood pressure within them. To prevent blood from flowing in the wrong direction, veins have special structures called valves at regular intervals. These valves only permit the flow of blood in one direction, ensuring blood continues to circulate correctly.

If we take a look at the options provided in the question, we can see that the correct answer is option (D): to prevent the backflow of blood.

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