<P> Pulmonary surfactant is a surface - active lipoprotein complex (phospholipoprotein) formed by type II alveolar cells . The proteins and lipids that make up the surfactant have both hydrophilic and hydrophobic regions . By adsorbing to the air - water interface of alveoli, with hydrophilic head groups in the water and the hydrophobic tails facing towards the air, the main lipid component of surfactant, dipalmitoylphosphatidylcholine (DPPC), reduces surface tension . </P> <P> As a medication, pulmonary surfactant is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system . </P>

Surfactant is released to reduce surface tension in the alveoli