What is the structure of avieoli?

Alveoli are tiny, balloon-like structures in the lungs where gas exchange occurs. Each alveolus is surrounded by a network of capillaries and is lined with a thin layer of epithelial cells, allowing for efficient diffusion of oxygen and carbon dioxide. The walls of alveoli are composed of elastic fibers, enabling them to expand and contract during breathing. Additionally, surfactant, a substance produced by type II alveolar cells, reduces surface tension, preventing alveoli from collapsing and aiding in their inflation.