AP BIOLOGY

Detailed explanation-1: -Veins have valves to prevent this backflow of blood. Valves ensure that blood flows only in one direction through veins. Therefore, veins have valves, not the arteries.

Detailed explanation-2: -Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don’t require valves because pressure from the heart is so strong that blood is only able to flow in one direction.) Valves also help blood travel back to the heart against the force of gravity.

Detailed explanation-3: -Typically, arteries lack valves. However, there are valves on the two arteries exiting the right and left ventricles that stop blood from flowing backward. Aortic and pulmonary valves are typically regarded as heart valves.

Detailed explanation-4: -Arteries can maintain that high blood pressure due to their strong lining and flexible walls that allow for the additional push of blood. Because of this unique design and the assistance they receive from the heart, they do not need valves to prevent backflow.

Detailed explanation-5: -All veins contain valves. Only two arteries (Pulmonary trunk & aorta) have valves, others don’t.