Question

Arteries do not have valves but veins do have them. Explain.

Answer 1

The main function of the valves in veins is to prevent back flow of blood. Blood in the arteries, after being pumped by the heart, is under much higher pressure than blood in veins. So there is no need for valves in arteries to prevent back flow. The blood present in veins is under much lower pressure as it is returning to the heart from the various organs and tissues.So it has a risk of back flow if the valves are not present to prevent it.

Aside from preventing back flow of blood, valves in the veins aid in the return of blood from the extremities to the heart (from feet and legs in particular).