Blood travels from your heart to the rest of your body through arteries to deliver oxygen and nutri...
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Blood travels from your heart to the rest of your body through arteries to deliver oxygen and nutrients before returning to the heart and lungs through veins to pick up more oxygen. Veins in the legs and lower body work against the force of gravity to return blood to the heart. The walls of the veins contain valves to prevent backflow. Muscles in the legs contract to squeeze the veins and pump the blood upward. Varicose veins are large, ropey veins in the legs. They are always expanded because the vein is having trouble bringing blood back to the heart. The veins usually begin to get bigger because pressure from gravity pushes down on the column of blood, and the thin-walled veins are pushed outward, making them bigger. Varicose veins are bigger and contain more blood, which puts more pressure on the valves which causes them to fail. Varicose veins are more common in older people, because of changes in aging veins. Veins become less elastic, so when stretched, they don't return to their previous shape. Valves in older veins weaken or won't close, so blood flows backwards and collects in pools. They appear blue because they're carrying blood that is returning to the lungs that lacks oxygen.