AP BIOLOGY

Detailed explanation-1: -Aortic valve: Allows blood to pass from the left ventricle to the aorta; prevents backflow of blood into the left ventricle.

Detailed explanation-2: -Veins often pump blood against the flow of gravity and make use of valves to prevent the blood from flowing downwards.

Detailed explanation-3: -What are Vein Valves? Interspersed throughout your veins are small crescent-shaped flaps of tissue, known as valves, that help prevent a backflow of blood. These valves project from the innermost layer of the vein wall to the center of the vein and are angled towards the heart in the direction of venous blood flow.

Detailed explanation-4: -Valves are found in veins to check the backflow of blood flowing under.