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.

Inside you, there is an amazing network of blood vessels, the tubes that carry blood all around your body. Every part of the body needs oxygen, food and water. The blood vessels are a bit like ...

Because blood vessels run across the surface of the retina ... it was something of a botched design. Biologists use the range of less complex light sensitive structures that exist in living ...

and the principle has been employed in human-led design as well. The lymphatic system plays a key role in maintaining the body's fluid balance and supporting immune defences. Lymphatic vessels are ...

Blood vessels are a series of tubes inside your body. They move blood to and from your heart. Arteries carry blood away from the heart and transport oxygen and useful nutrients to the body's cells.