Surfactant
During gestation, the lungs do not participate in gas exchange. However, they perform vital preparatory work:
- Type II cells of the alveoli produce surfactant, which reduces surface tension and prevents alveolar collapse during post-natal respiration.
- The importance of this is highlighted by neonatal respiratory distress syndrome (aka, hyaline membrane disease), in which insufficient surfactant allows alveolar collapse (atelectasis) upon exhalation. Infants born prematurely are at higher risk, as their surfactant production is incomplete.