BLOOD FLOW round and round the body in a system of tubes called blood vessels. It is pumped by the heart, which has hollow chambers with strong muscular walls that contract to push the blood through the vessels. Blood carries many substances that are vital for life. These include oxygen and glucose (blood sugar) for energy, nutrients and raw materials for growth and repair, and natural body chemicals, called hormones, that control internal processes. At the same time, blood also takes away wastes and unwanted materials, including carbon dioxide, which is breathed out in the lungs.
INFO:
An average adult man has a blood volume of 5 - 6 liters. An average adult woman has a blood volume of 4 - 5 liters.
