How do the structure and function of alveoli contribute to gas exchange?

The structure and function of alveoli are crucial for effective gas exchange within the lungs, and the large surface area paired with thin walls is fundamental to this process. Alveoli are tiny air sacs that maximize the area available for gas exchange; a greater surface area allows for more oxygen to diffuse into the blood and more carbon dioxide to diffuse out. The thin walls of the alveoli, made up of simple squamous epithelium, facilitate rapid diffusion of gases. This is essential because gas exchange relies on the efficiency of diffusion—thinner barriers allow gases to move more freely and quickly between the alveoli and the surrounding capillaries.

This large surface area and thinness collectively optimize the respiratory process, ensuring that oxygen is absorbed into the blood efficiently and that waste gases are expelled effectively. While capillaries are indeed densely packed around the alveoli to enable efficient gas transfer, muscles are not present in the alveolar walls, and they do not have a solid structure for support; rather, they rely on the surfactant and elastic properties to maintain their shape during respiration.