List three properties of alveoli that make them an efficient gas exchange surface

Large Surface Area: Alveoli are tiny sacs within our lungs that can stretch open to accommodate a large volume of gas. The human lungs contain about 300-500 million alveoli, all of which contribute to a surface area of approximately 70 square meters. This large surface area increases the amount of gas that can be exchanged at any one time.

Thin Walls: The walls of the alveoli are extremely thin (about 0.2 micrometers). This short distance allows gases to quickly diffuse across the alveolar and capillary walls.

Rich Blood Supply: Each alveolus is surrounded by a network of capillaries, which carry deoxygenated blood from the heart to the lungs. The rich blood supply allows for efficient uptake of oxygen into the blood and removal of waste carbon dioxide.