What it the alveolars lined with?

Answer 1

The alveoli, which are tiny air sacs in the lungs, are lined with a thin layer of epithelial cells called alveolar epithelium. This lining consists primarily of two types of cells: type I alveolar cells, which facilitate gas exchange, and type II alveolar cells, which produce surfactant to reduce surface tension and prevent alveolar collapse. The alveolar walls also contain a network of capillaries that enable the exchange of oxygen and carbon dioxide between the air and blood.