Gas exchange
Inhaled and exhaled air
Compared to atmospheric air, exhaled air contains:
- less oxygen
- more carbon dioxide
- more water vapour
The composition of inhaled air differs to exhaled air, this is because of Diffusion of gases, often carbon dioxide and oxygen in the alveoli (air sacs). in the alveoli.
Gas exchange in the lungs
Gas exchange in the lungs happens in the Tiny air sacs in the lungs, where gas is exchanged during breathing.. Some of the features of alveoli include:
- thin walls (just one cell thick) to reduce the diffusion distance
- large surface area for maximum exchange of gases
- moist surface for the dissolving of gases in alveolar air so that they can diffuse across the alveolar walls
- rich blood supply to remove diffused gases and maintain a concentration gradient for further diffusion
Rhys is out of breath after walking to his camping destination. His science app, Alfred, helps him to breathe correctly by explaining the process of gas exchange.