What is the role of alveoli in the lungs?
1 Answer
The alveolus is a hollow cavity found in the lung parenchyma and is the
#"basic unit of ventilation"# .
Explanation:
The alveoli consists of an epithelial layer and an extracellular matrix surrounded by small blood vessels called capillaries.
Each alveolus is surrounded by numerous capillaries and is the site of gas exchange, which occurs by diffusion.
Type II cells in the alveolar walls secrete pulmonary surfactant. This film of fatty substances contributes to the lowering of alveolar surface tension without which the lungs would collapse.
Alveolar macrophages reside on the internal surface of air cavities of the alveoli, the alveolar ducts and the bronchioles. These act as mobile scavengers that serve to engulf foreign particles in the lungs such as dust, bacteria, carbon particles and blood cells from injuries.
