Adaptations of the Alveoli (Edexcel GCSE Biology)

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