Question:
Describe how alveoli are adapted for gas exchange.
Solution:
The alveoli have the following adaptations:
1. Large surface area: this increases and facilitates gas exchange.
2. Thin walls: alveolar walls are one cell thick providing gases with a short diffusion distance.
3. Moist walls: greater ease of gas diffusion, since gases dissolve in the moisture helping them to pass across the gas exchange surface.
4. Permeable walls.
5. Extensive blood supply: this ensures that oxygenated blood is removed from the lungs and blood with high concentrations of carbon dioxide is carried to the lungs.
6. A large diffusion gradient: the oxygen concentration in the alveoli is higher than in the capillaries, so oxygen moves from the alveoli into the blood. Then, carbon dioxide diffuses in the opposite direction.