Question

what structures keep blood in the blood vessels from following back to the ventricles​

Answer 1

Answer:

Flow of blood in the blood vessels is unidirectional and this is maintained by valves

Valves prevent the blood from flowing in backward direction

Answer 2

Blood is not allowed to flow back into the ventricles by semilunar valves.

• The heart contains 4 important valves. Two of these lie at the junction of each auricle and ventricle.
• Two semilunar valves are present near the exit of each ventricle. One is located at the opening of the pulmonary artery. The other is at the opening into the aorta.
• These two semilunar valves are flaps that open only in the direction of flow of the blood- away from the heart. Hence, they keep blood from flowing back to the ventricles.