2.46 Explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries

The alveoli are adapted to the job of making gas exchange quick and effective because (they have...) :

• Walls one cell thick make diffusion quick and easy
• There are a lot and they look a bit like bunches of grapes, meaning an enormous surface area - this means the blood stream is in contact with a large surface, and gas exchange happens quickly
• Moist lining helps gases dissolve and diffuse into it
• Constant blood flow allows all the blood to be oxygenated effectively

Figure 1: Diagram :)