How are the alveoli designed to maximise the exchange of gases?
The alveoli are the small balloon-like structures present in the lungs. The walls of the alveoli consist of extensive network of blood vessels. Each lung contains 300−350 million alveoli, making it a total of approximately 700 million in both the lungs. The alveolar surface when spread out covers about 80 m2area. This large surface area makes the gaseous exchange more efficient.