It is returned to the heart in the veins. The capillaries connect the two types of blood vessel, and molecules are exchanged between the blood and the cells across their walls.

The blood vessels are shown in purple (1) and the pericytes in green (2). Biology in the background Blood vessels provide nutrients and oxygen to cells, remove cellular waste products, enable ...

Revise GCSE ... Bitesize Biology. This series is all about homeostasis. You’re in luck because that means we’re covering everything from the nervous system and hormones to blood glucose ...