What are the alveoli adapted for gas exchange

In alveoli, oxygen in the air diffuses into the bloodstream and carbon dioxide diffuses out of the bloodstream and back into the air. Alveoli have several adaptations to make the rate of gas exchange as fast as possible: The millions of alveoli in the lungs give them a huge surface area, secondly the alveoli have very thin walls so the diffusion path is short and alveoli have a very god blood supply