ANIMAL PHYSIOLOGY
HUMAN CIRCULATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Release excessive pressure to protect these thin-walled vessels.
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Counteract the crushing force of surrounding skeletal muscles.
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Prevent backflow of blood in the absence of high blood pressure.
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Adjust blood pressure by compartmentalizing the venae cavae.
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Detailed explanation-1: -They are larger and hold more blood than the arteries. The blood passing through the veins is deoxygenated (except in pulmonary veins ) and flows at a low pressure. It flows slow and steady against the direction of gravity. Therefore, veins have valves to prevent the backflow of blood.
Detailed explanation-2: -Final answer:The valve which prevents back flow of blood in the veins is Semilunar valve.
Detailed explanation-3: -Blood flows under low pressure in veins. Hence, veins have valves to prevent the backflow of blood and make sure the blood keeps moving regularly.
Detailed explanation-4: -If gravity or muscle contractions try to pull the blood backward or if blood begins to back up in a vein, the flaps are pushed closed, so the blood does not flow backward. Thus, valves help the return of blood to the heart-by opening when the blood flows toward the heart and closing when blood might flow backward.