Adaptations of the Alveoli
- The lungs are the gas exchange surface in humans and so are adapted to maximise the exchange of gas by diffusion
- Inside the lungs there are many rounded alveolar sacs which give a very large surface area to volume ratio
- These alveoli are highly specialised structures
- They (and the capillaries around them) have thin, single layers of cells to minimise diffusion distance
- Ventilation maintains high levels of oxygen and low levels of carbon dioxide in the alveolar air space
- A good blood supply ensures constant supply of blood high in carbon dioxide and low in oxygen
- A layer of moisture on the surface of the alveoli helps diffusion as gases dissolve
Alveoli are specifically adapted to maximise gas exchange
