Final answer:
Type II alveolar cells, or type II pneumocytes, perform two vital functions. They secrete pulmonary surfactant to reduce surface tension and prevent alveolar collapse, and they regenerate the alveolar wall by differentiating into type I cells for repair.
Step-by-step explanation:
The type II alveolar cells, also known as type II pneumocytes, have two important functions in the respiratory system. First, they secrete pulmonary surfactant, which is a substance composed mainly of phospholipids and proteins. This surfactant is critical for reducing the surface tension within the alveoli, thereby preventing their collapse during exhalation and facilitating the process of breathing.
Secondly, type II alveolar cells play a role in the repair and regeneration of the alveolar wall, particularly after lung injury. They can divide and differentiate into type I alveolar cells (squamous epithelial cells), which are responsible for most of the gas exchange surface area of the alveoli. This capability is essential for maintaining the integrity and function of the lung's alveolar structure.