HISTOLOGY
BLOOD VESSELS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Veins have valves that prevent blood from falling backwards.Why would this happen if there were no valves?One, some or all answers could be correct?
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Blood is much heavier in veins
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Blood in veins is at a lower pressure
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Gravity is in the opposite direction to the flow of blood
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Blood is much thicker in veins
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Explanation:
Detailed explanation-1: -Veins have valves which stop the blood from flowing backward. This is because blood pressure in veins is very low (compared to arteries).
Detailed explanation-2: -Veins, on the other hand, are thin-walled and carry deoxygenated blood which comparatively has low pressure. So since it can flow in the opposite direction as its pressure is low, veins have valves to make sure that there is no backflow of blood.
Detailed explanation-3: -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.
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