Type II alveolar cells are the round-shaped or cuboidal epithelial cells. These cells have a free surface with microvilli. The function of the type II alveolar cells is to secrete the alveolar fluid to keep the surface of the cells moist.
A mixture of phospholipids and lipoproteins is present in the alveolar fluid that serves as surfactant and reduces the surface tension of the alveolar fluid. The overall effect of the presence of surfactant in alveolar fluid is to protect the alveoli against collapsing during exhalation.
