NEET PG DENTAL EXAM

Detailed explanation-1: -Veins above the heart return blood to the heart with the help of gravity. But the veins below the heart must work against gravity. The blood in these veins is propelled by the milking action of skeletal muscle contractions. One-way valves insure that the blood is propelled in the correct direction-toward the heart.

Detailed explanation-2: -As blood moves through the capillaries, the oxygen and other nutrients move out into the cells. Then waste matter from the cells goes into the capillaries. As the blood leaves the capillaries, it moves through the veins. Veins merge into larger tubes to carry the blood back to the heart.