why do veins have valves but arteries don't have it?
- Veins have valves within them to prevent back flow of blood. Veins do not have as many elastic fibers as arteries. The valves keep the blood from pooling and flowing back to the legs under the influence of gravity.
- But Arteries have elastic fibres and because of the elasticity they can expand to accept a volume of blood and then contract and squeeze back to their original size after the pressure is released. This property helps to maintain the pressure on the blood when the heart relaxes and keeps it flowing forward. Since there is no back flow, therefore Arteries do not have valves.