Lung anatomy

Carbon dioxide is removed from the blood in the lungs to prevent the pH of the blood becoming too acidic.

Lungs are adapted for gas exchange:

• Alveoli have a thin wall only one cell thick so there is a short distance for diffusion.

• Moist membrane accelerates the diffusion of gases.

• Shape of alveoli provides large surface area for diffusion.

• Extensive capillary network surrounding alveoli.

• Well-ventilated to maintain a large diffusion gradient.