Surfactant secreted by type II pneumocytes primarily functions to:

• A Increase alveolar surface tension to prevent over-expansion
• B Reduce alveolar surface tension to prevent alveolar collapse ✓
• C Increase lung compliance by increasing elastic recoil
• D Enhance diffusion of O2 across the alveolar membrane

Explanation

Surfactant, primarily dipalmitoylphosphatidylcholine (DPPC), reduces alveolar surface tension by disrupting the cohesive forces between water molecules at the air-liquid interface. According to the Law of Laplace (P = 2T/r), reduced surface tension prevents smaller alveoli from collapsing and contributes to alveolar stability. Deficiency of surfactant in premature neonates results in Respiratory Distress Syndrome (RDS) due to widespread alveolar atelectasis.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.