Question

Which valves prevent the backward flow of blood
into the ventricles from pulmonary artery and
systemic aorta?​

Answer 1

Answer:

Once blood is pumped out of the left ventricle and into the aorta, the aortic semilunar valve (or aortic valve) closes preventing blood from flowing backward into the left ventricle.

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Answer 2

Answer:

Once blood is pumped out of the left ventricle and into the aorta, the aortic semilunar valve (or aortic valve) closes preventing blood from flowing backward into the left ventricle.