Surfactant production in the lungs

Surfactant production in the lungs starts at:

A. 28 weeks
B. 32 weeks
C. 34 weeks
D. 36 weeks

Answer is A. 28 weeks.

Pulmonary surfactant is a surface-active lipoprotein complex formed by type II alveolar cells in the pulmonary alveoli. An alveolus is an anatomical structure that has the form of a hollow cavity. Found in the lung, the pulmonary alveoli are spherical outcroppings of the respiratory bronchioles and are the primary sites of gas exchange with the blood.

Surfactant production in humans begins in Type II cells during the terminal sac stage of lung development. Lamellar bodies appear in the cytoplasm at about 20 weeks gestation. These lamellar bodies are secreted by exocytosis into the surface water layer lining the alveolar airspace, where the surfactant forms a meshwork of tubular myelin.

The surfactant production starts around 20 weeks of life as described above and peaks at 35 weeks of gestation. Hence, the best possible answer among the options given is 28 weeks.

Surfactant deficiency is the basic abnormality in respiratory distress syndrome due to preterm delivery.