Gaseous Exchange

Gaseous exchange is the process whereby inhaled oxygen is infused into the bloodstream and waste carbon dioxide is removed from the blood in order to allow its excretion.

The actual process occurs in the alveoli in the lungs- tiny air sacs with minute blood vessels running by. The membrane of these blood vessels is very thin, and at the correct pressure oxygen can cross over the membrane and into the bloodstream, whilst the carbon dioxide is sent the other way. Although the actual alveoli are very small, they have a large surface area and there are many of them. Estimates suggest that if the surface area of the alveoli in an adult human lung were laid flat, they would cover an area the size of a tennis court!