Surface Tension:

• Definition: Surface tension is the force exerted by the thin liquid layer lining the alveoli in the lungs, which tends to pull the alveolar walls together.

• Role of Surfactant: Surfactant, a substance secreted by type II alveolar cells, reduces surface tension. It prevents the collapse of alveoli by lowering the force needed to inflate them.

Effects on Lung Function:

• Alveolar Stability: Surfactant helps maintain alveolar stability, ensuring that smaller alveoli do not collapse into larger ones, which aids in even gas exchange.

• Work of Breathing: By reducing surface tension, surfactant decreases the effort required to inflate the lungs, making breathing easier.

• Preventing Collapse: In conditions where surfactant is deficient (e.g., neonatal respiratory distress syndrome), alveoli tend to collapse, leading to difficulty in breathing and impaired gas exchange.