Gas exchange occurs over a gas exchange surface - boundary between the outside environment and the internal environment of the organism.

Oxygen and carbon dioxide need to quickly diffuse across the surface.

Gas exchange surfaces:

Maintenance of a steep concentration gradient of gases across the exchange surface, increases the rate of diffusion.

Diffusion only efficient over small distances - multicellular organisms have evolved with specialised gas exchange surfaces.

	Created by Melissa Lamb about 7 years ago

Notes on gas exchange surfaces and gas exchange in insects.