Which type of cells are responsible for producing surfactant in the alveoli?

• A. Type I alveolar cells
• B. Type II alveolar cells
• C. Type III alveolar cells
• D. Bronchial epithelial cells

Answer: (B)

Surfactant production in the alveoli is primarily the responsibility of Type II alveolar cells, which are also known as surfactant-producing cells or pneumocytes. These cells are vital for reducing surface tension within the alveoli, which prevents their collapse during the process of exhalation. Surfactant is a complex mixture of lipids and proteins that plays a crucial role in maintaining alveolar stability, facilitating gas exchange, and enhancing lung compliance. By lowering surface tension, surfactant ensures that alveoli remain open and functional, particularly in the initial stages of breathing.

Type I alveolar cells, although they are the most abundant cells in the alveolar walls, primarily function as structural components and are involved in the gas exchange process due to their thin, flat morphology. Their role is not in producing surfactant but rather in allowing for the efficient diffusion of oxygen and carbon dioxide across the alveolar-capillary membrane.

Type III alveolar cells are not a recognized type in the classification of alveolar cells and are sometimes mistakenly mentioned but do not play a role in surfactant production. Similarly, bronchial epithelial cells focus mainly on airway protection and mucus production rather than surfactant secretion. Thus, the role of Type II alveolar