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.

So it's a good job we've got the circulatory system to transport nutrients, water and oxygen to the entire body. Inside you, there is an amazing network of blood vessels, the tubes that carry ...

Locate the vessels entering and leaving the heart and the 2 heart chambers - atrium and ventricle. Look at diagram ... of circulatory and respiratory system is important. Think carefully about ...

There are three types of blood vessel: arteries, veins and capillaries. The heart is a muscular organ that pumps blood around your circulatory system. The circulatory system is the heart and all ...