Lung Prematurity

Pulmonary surfactant is a mixture of lipids and proteins that is produced by alveolar type II epithelial cells (AEC2) and secreted into the airspaces. Phospholipids are the major component of surfactant by weight, and are essential for lowering surface tension at the air-liquid interface, which prevents alveolar collapse at end-expiration. Four proteins highly expressed in the lung and found in surfactant are designated surfactant proteins (SP) A, B, C, and D. Additional proteins including ABCA3 and NKX2.1 are also important for the production of functional surfactant. The surfactant proteins are developmentally regulated, such that their expression increases in later gestation