Definition: alveoli -

alveoli Alveoli are formed to increase the density of gas exchange surface on the acinar airway tree, thus facilitating diffusion of oxygen to and into the capillaries

Alveoli are thin-walled, sac-like structures lined by a single layer of flattened squamous epithelial cells: type I pneumocytes This extremely thin nature of alveoli Lung alveoli: anatomy and structure The alveoli of the lung are small air sacs that have extremely thin tissue walls The alveoli have a large