Veins act since the return route for blood that has delivered oxygen and nutrients to overall body tissues. Soon after this exchange takes place inside the capillaries, veins carry the oxygen-depleted blood back to the heart and lungs for reoxygenation. Age: As we age, the valves from the veins weaken, https://cashuitem.wikigop.com/1190081/detailed_notes_on_painful_veins_in_legs_singapore