What is pulmonary surfactant? What is its physiological significance?

Surfactant in the alveoli is a type of human phospholipoprotein whose primary function is to reduce surface tension in the lungs.

Pulmonary surfactant is a complex substance produced by type II alveolar cells. The proteins and lipids that constitute surfactant contain both hydrophilic and hydrophobic regions. Components of surfactant such as dipalmitoylphosphatidylcholine adsorb onto the air-water interface of the alveoli, with their hydrophilic head groups in the aqueous phase and hydrophobic tails oriented toward the air. This arrangement reduces surface tension in the lungs and helps improve overall lung compliance.

When production or function of pulmonary surfactant is impaired, it may lead to diseases such as emphysema, neonatal respiratory distress syndrome, and acute lung injury. Individuals experiencing symptoms such as chest pain, chest tightness, or shortness of breath—suggestive of these conditions—should seek medical evaluation promptly to avoid delays in diagnosis and treatment.