NEET PG DENTAL EXAM

Detailed explanation-1: -Medium and large veins have venous valves, similar to the semilunar valves associated with the heart, that help keep the blood flowing toward the heart. Venous valves are especially important in the arms and legs, where they prevent the backflow of blood in response to the pull of gravity.

Detailed explanation-2: -The one-way venous valves in deep veins prevent blood from flowing backward, and the muscles surrounding the deep veins compress them, helping force the blood toward the heart, just as squeezing a toothpaste tube ejects toothpaste.

Detailed explanation-3: -Because most veins must move blood against the pull of gravity, blood is prevented from flowing backward in the veins by one-way valves.

Detailed explanation-4: -Veins often pump blood against the flow of gravity and make use of valves to prevent the blood from flowing downwards.