Question

Veins have valves to prevent the backflow of blood because the blood in veins flow ________.

• A. at a low pressure
• B. at a high pressure
• C. at a neutral pressure
• D. at atmospheric pressure

Answer 1

The correct option is A

at a low pressure

Veins are blood vessels which bring blood from the body back to the heart. They are larger and hold more blood than the arteries. The blood passing through the veins is deoxygenated (except in pulmonary veins) and flows at a low pressure. It flows slow and steady against the direction of gravity. Therefore, veins have valves to prevent the backflow of blood.