Lung surfactants are made from animal lung extract and contain phospholipids. Natural surfactant is produced by the alveolar cells in the lungs and line mainly the alveoli and small bronchioles, and prevents the alveoli from collapsing. Lung surfactant makes it easier for oxygen to penetrate the lung surface lining and move into the blood. Without the lung surfactant it would be extremely hard to breathe, and transfer of oxygen through the surface that lines the lungs would be very difficult.
Natural surfactant is produced by the fetus before they are born and their lungs are prepared to breathe properly by about 37 week gestation. In unexpected circumstances where labor starts early or a pre-term emergency caesarean is performed, lung surfactant is given intratracheally to the premature infant to prevent respiratory distress syndrome.
