Question

Give reason for the following.
2 Veins have valves but artery do not have.

3. Double circulation in birds and Mammals helps in temperature

regulation.​

Answer 1

Answer:

2) 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.

3) Double circulation supports a strict separation of both oxygenated and deoxygenated blood. Therefore, this circulation ensures that the body always has a dedicated supply of oxygen also, it improves body efficiency. This is also one of the reasons why mammals can maintain their body temperatures.

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