Which of the following blood vessels contain valves?

Veins are the blood vessels that contain valves, and this feature is essential for their function. The primary role of valves in veins is to prevent the backflow of blood, ensuring that it flows toward the heart, especially in the extremities where blood must travel against the force of gravity.

In the circulatory system, veins collect deoxygenated blood from various parts of the body and channel it back to the heart. As the blood moves through the veins, particularly in the legs and arms, the muscle contractions around the veins help propel the blood forward. Valves in the veins open in the direction of blood flow and close to prevent any backflow, maintaining efficient circulation.

In contrast, arteries generally do not contain valves because they carry oxygenated blood away from the heart under high pressure. Capillaries, being the smallest blood vessels, facilitate the exchange of gases, nutrients, and waste products at the cellular level and do not possess valves either. Therefore, the presence of valves is a distinctive feature of veins, reflecting their unique function and role within the circulatory system.