TY - CHAP M1 - Book, Section TI - Pulmonary Surfactant and Pulmonary Alveolar Proteinosis A1 - Towe, Christopher A1 - Trapnell, Bruce C. A2 - Kline, Mark W. PY - 2018 T2 - Rudolph's Pediatrics, 23e AB - Pulmonary surfactant is a lipoproteinaceous substance that normally comprises a thin film lining alveoli, where it functions to reduce surface tension, thereby preventing alveolar collapse and leakage of capillary fluid into the alveolar lumen. It is composed of mostly polar phospholipids (∼85%) with smaller amounts of neutral lipids (∼5%, mostly cholesterol) and proteins (∼10%, surfactant protein [SP]-A, SP-B, SP-C, and SP-D). SP-B and SP-C are surface active, whereas SP-A and SP-D are members of the collectin family, part of host innate immunity. Surfactant lipids and proteins both contribute to its surface tension–lowering properties, and surfactant proteins also participate in regulation of surfactant metabolism, microbial pathogen clearance, and regulation of alveolar macrophage functions. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - accesspediatrics.mhmedical.com/content.aspx?aid=1182917826 ER -