Question

The alveolar cell that secretes pulmonary surfactant is the

a. alveolar type II cell.
b. alveolar macrophages.
c. dust cells.
d. squamous alveolar cell.
e. alveolar type I cell.

Answer 1

The alveolar type II cell is responsible for the secretion of pulmonary surfactant. This substance is critical for reducing surface tension in the alveoli, preventing their collapse during exhalation, and is particularly important for the respiratory health of premature infants.

Step-by-step explanation:

The alveolar cell that secretes pulmonary surfactant is the alveolar type II cell. These are cuboidal epithelial cells that constitute the minor cell type within the alveolar wall. The primary function of alveolar type II cells is to secrete pulmonary surfactant, a mixture of phospholipids and proteins that significantly reduce the surface tension of the alveoli.

Without the pulmonary surfactant, alveoli would collapse during exhalation due to high surface tension caused by the water in the lining of the alveoli. Another cell type, the alveolar macrophage, plays a different role in the alveolus by removing debris and pathogens. In contrast, the type I alveolar cell, being a squamous epithelial cell, is the major cell type in the alveolar wall and is highly permeable to gases but does not secrete surfactant.

It is crucial especially in premature infants, as insufficient production of surfactant by type II cells can lead to difficulty inflating the lungs, a condition known as respiratory distress syndrome.