Question

Veins have valves which allow blood to flow only in one direction. Arteries do not have valves. Yet the blood flows in one direction only. Can you explain why?

Answer 1

Blood in the arteries, after being pumped by the heart, are under a much higher pressure than blood in veins. So the internal pressure of the blood in the vessel far outweighs the risk of a back flow. Hence valves are absent in arteries.