If you clench your hand into a fist, this is approximately the same size as your heart. It is located in the middle of the chest and slightly towards the left. The heart is a large muscular pump ...

All blood vessels are specifically structured to perform their function. For example, a capillary is microscopically thin to allow gases to exchange, the arteries are tough and flexible to cope ...

If you're revising for GCSE PE get help on the Bitesize pages of the BBC Schools website. It's one of the best revision aids around. Bitesize is a website that gives students studying GCSEs in England ...