Explain5 marksStandard
A medical researcher is studying the structure of alveoli in mammalian lungs. She notes the following features:
- The walls of alveoli are very thin, consisting of a single layer of squamous epithelial cells.
- Each alveolus is surrounded by a dense network of capillaries.
- The capillaries also have very thin walls, composed of a single layer of endothelial cells.
- The inner surface of each alveolus is lined with a thin film of moisture.
- The total surface area of all alveoli in the lungs is very large.
Explain how these features contribute to efficient gas exchange between alveolar air and blood.