ABSTRACT
This chapter gives an overview of the pulmonary surfactant system and its composition, surface behavior, and physiological actions. Coverage describes why surface tension and surfactants are important in the lungs and how the Laplace equation shows that surface active agents are necessary to reduce the work of breathing and to stabilize alveolar inflation and deflation. The discovery of lung surfactant is discussed, and its biochemical components are summarized. Alveolar type II epithelial cells and their crucial roles in the synthesis, secretion, and recycling of lung surfactant are also covered. The biophysical behaviors and surface properties responsible for the physiological activity of endogenous lung surfactant are also described. The direct effects of all lung surfactants on respiratory function follow from their specific adsorption and dynamic surface tension lowering properties as discussed here. Further details on the componentbased surface active biophysics and physiological activity of endogenous and exogenous lung surfactants are given in subsequent chapters.
