Question

) What prevents back flow of blood during contraction?​

Answer 1

The answer to this question is Valves.

Valves maintain direction of blood flow. They are like tight barriers used to prevent back flow of blood and also ensures the flow of blood in same direction. It does this job by opening and closing a series of valves tightly.

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Answer 2

The veins have valves present in them which controls the backflow of blood....they make sure that the blood is flowing in the right direction only......arteries do not need valves because the pressure created on them when the ventricles of the heart contract and pump blood into them is enough to ensure the blood flow in the forward direction only

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