What is the internal structure of the alveoli?

The internal structure of the alveoli consists of thin walls made up of a single layer of epithelial cells, primarily type I pneumocytes, which facilitate gas exchange. These walls are surrounded by a network of capillaries, allowing oxygen and carbon dioxide to diffuse between the air in the alveoli and the blood. Additionally, type II pneumocytes produce surfactant, a substance that reduces surface tension and prevents the alveoli from collapsing. The alveolar structure is highly specialized to maximize surface area for efficient gas exchange.