Surfactant Production — FRCA Primary MCQ
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Correct answer: D — Type II pneumocytes
Type II pneumocytes synthesise pulmonary surfactant and store it within lamellar bodies before secretion into the alveolar lining fluid. Surfactant is a mixture of phospholipids, particularly dipalmitoylphosphatidylcholine, and surfactant-associated proteins. It lowers surface tension at the alveolar air–liquid interface, limiting end-expiratory alveolar collapse and increasing lung compliance. Type I pneumocytes are thin cells specialised for gas exchange. Goblet cells secrete airway mucus, while club cells are non-ciliated bronchiolar secretory cells rather than the principal source of alveolar surfactant. Alveolar macrophages provide phagocytic defence and participate in surfactant clearance and catabolism, but do not synthesise the alveolar surfactant pool.
Reference: Hall SB, Zuo YY. The biophysical function of pulmonary surfactant. Biophysical Journal. 2024;123(12):1519–1530. https://pubmed.ncbi.nlm.nih.gov/38664968/