Your circulatory system is made up of three parts: the heart, blood vessels and the blood itself. Your heart keeps all the blood in your circulatory system flowing. The blood travels through a ...

Each 2.54 square centimetre (a square inch) of human skin has six metres (20ft) of blood vessels. Veins hold about 65 per cent of the body's blood and have one-way valves tohelp blood move.