Question

Why do veins have valves?

Answer 1

Answer:

becoz the blood flows at high pressure in veins

Answer 2

Answer:

Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don't require valves because pressure from the heart is so strong that blood is only able to flow in one direction.) Valves also help blood travel back to the heart against the force of gravity.

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