Bitesize has changed! We're updating subjects as fast as we can. Visit our new site to find Bitesize guides and clips - and tell us what you think!
Print

Science

Blood circulation

Circulation

Blood is pumped at high pressure away from the heart in arteries. It travels through networks of thin capillaries, where it can exchange materials with the tissues. It's then collected up and returned to the heart at low pressure in veins.

How different blood vessels are adapted for their function - higher tier

Blood vesselFunctionAdaptions
Arterycarry blood away from heart at high pressurethick, elastic, muscular walls to withstand pressure and to exert force (pulse)
Capillaryallow exchange of materials between blood and tissuesthin permeable walls
Veinreturn low pressure blood to heartLarge diameter to offer least flow resistance. Valves to prevent back flow.

Cross-section of a vein

Back to Living and growing index

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.