Final answer:
Pulmonary surfactant is crucial for reducing surface tension to prevent alveolar collapse, ensuring easier lung inflation and stable gas exchange.
Step-by-step explanation:
Pulmonary surfactant coats the inner alveolar surface to reduce surface tension and prevent alveolar collapse. This substance is critical in maintaining the structure and function of alveoli during respiration. Pulmonary surfactant is essentially a detergent-like liquid that works to reduce the inherently high surface tension at the air-water interface of the alveoli, a tension that stems from the interaction of water molecules. Surfactant decreases this tension, thereby preventing the collapse of alveoli during exhalation and easing the process of inflation during inhalation.
Without it, the alveoli would be at a high risk of collapsing upon themselves, a condition that particularly affects premature infants who may lack sufficient surfactant and may suffer from respiratory distress syndrome as a consequence. Surfactant's unique properties not only inhibit alveolar collapse but also prevent larger alveoli from over-expanding, thus maintaining an equilibrium that is critical for efficient gas exchange.