Pulmonary surfactant is secreted by ?

Ans. is 'b' i.e., Type II PneumocytesSurfactant Surfactant is a Soap-like substance secreted by the type-II pneumocytes of the alveolar epithelium.It is a mixture of dipalmitoyl-phosphatidycholine (dipalmitoyl-lecithin), phosphatidylglycerol, other phospholipids, neutral lipids, Surfactant proteins A, B, C and D (SP-A, SP-B, SP-C and SP-D), and carbohydrates.Surfactant reduces the alveolar surface tension. This has three impoant physiological consequences : ?1) t reduces the collapsing tendency of lungs.2) It reduces the natural tendency of the smaller alveoli to collapse and empty into the larger ones. This is called alveolar stabilization.3) It reduces the tendency of the alveolar interstitial fluid to transudate out into the alveolar space.Dipalmitoyl-phosphatidylcholine (dipalmitoyl-lecithin) is the main surface tension lowering phospholipid in surfactant.