The alveoli structure is special as it helps it with its function.
• The alveoli is folded (look at its shape). This, therefore, increases the surface area to volume ratio - increasing the rate of diffusion of gases (oxygen and carbon dioxide)
• The alveoli has a thin layer of moisture. This makes diffusion of gases more efficient as the moisture helps diffuse the gaseous substances faster.
• Surrounding by a lot of capillaries. Thus, this supply a lot of blood to the alveoli - diffuse carbon dioxide from deoxygenated blood and diffuse oxygen into the oxygenated blood.
• The walls of the alveoli are one cell thick. This gives the oxygen and the carbon dioxide a short pathway for diffusion - making it diffuse faster.