ABSTRACT
Lung surfactant is an extracellular phospholipid and protein-rich material that forms an interfacial barrier between the pulmonary alveolar gas phase and the alveolar epithelial cell lining. The presence of lung surfactant is essential for life. Its primary physiological role is to maintain a low surface tension in the alveolar space of the lung, especially at low lung volumes, thereby stabilizing the alveoli and permitting efficient gas exchange. In the absence of surfactant, as illustrated by the respiratory distress syndrome (RDS) of the neonate, alveolar collapse compromises lung gas exchange, leading to asphyxia. Thus, the factors that determine the presence of adequate extracellular surfactant are of major importance for understanding normal respiratory physiology.
