Question

give the answer of (2) and (5)​

Answer 1

Answer:

ans 2.The atrioventricular septum is the middle portion of the cardiac wall that divides the heart into left and right sides. This division takes place over just 10 days in the 4th and 5th week of an embryo's development. Its job is to prevent mixing of oxygenated and unoxygenated blood.

ans 5.The return of blood to the heart is assisted by the action of the skeletal- muscle pump. As muscles move, they squeeze the veins running through them. Veins contain a series of one-way valves, and they are squeezed, blood is pushed through the valves, which then close to prevent backflow.

Explanation:

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