Explain how capillaries are adapted to their function of exchanging substances, giving 3 examples.

Firstly, capillaries are one cell thick and so this makes them very thin. This reduces the diffusion pathway between the capillary and other cells thus allowing efficient diffusion. Secondly, capillaries also reduce the diffusion pathway by being situated in areas where exchange tissues are found, e.g. alveoli in the lungs, and thus this increases exchange efficiency. Finally, capillaries are also arranged in networks known as capillary beds, and thus multiple capillaries are spread over a large area. This increases efficiency of exchange as this increases surface area for which exchange can occur.