Question

Respiratory distress syndrome is common in premature infants as their lungs lack

• A. Dipalmitoyl lecithin
• B. Phosphatidyl ethanolamine
• C. Phosphatidyl choline
• D. Inositol triphosphate

Hint:

Pulmonary Surfactant: Major active component = Dipalmitoyl Lecithin (DPPC). Deficiency causes Neonatal Respiratory Distress Syndrome (RDS).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Infant Respiratory Distress Syndrome (RDS Hyaline Membrane Disease) results from developmental deficiency of pulmonary surfactant phospholipids.

Step 2: Detailed Explanation:
Neonatal Respiratory Distress Syndrome (RDS):
- Type II alveolar pneumocytes synthesize and secrete Pulmonary Surfactant, whose primary surface-tension lowering component is Dipalmitoyl Lecithin (Dipalmitoylphosphatidylcholine DPPC), a disaturated phospholipid.
- DPPC reduces surface tension at the alveolar air-liquid interface to near zero, preventing end-expiratory alveolar collapse (atelectasis).
- Premature neonates born before 32--34 weeks lack mature DPPC surfactant synthesis, causing alveolar collapse and respiratory failure.

Step 3: Final Answer:
Therefore, lungs of premature infants lack Dipalmitoyl lecithin, corresponding to option (A).