Question:easy
In respiratory distress syndrome (RDS) in a child, which cells are found to be defective?
In respiratory distress syndrome (RDS) in a child, which cells are found to be defective?
Show Hint
Think about which alveolar cell makes surfactant (DPPC).
Updated On: Jun 23, 2026
- Type 1 pneumocytes
- Type 2 pneumocytes
- Bronchial epithelium
- None
Show Solution
The Correct Option is B
Solution and Explanation
Clinical pearl: Surfactant equals Type II pneumocytes. Memorise that the alveolus has two cell types: Type I are flat lining cells for gas exchange, Type II are the granular secretory cells that pump out surfactant.
Why Type 2 is correct: Surfactant is mostly dipalmitoylphosphatidylcholine (DPPC / lecithin). It acts like a detergent and keeps alveoli open by reducing surface tension. Premature or sick infants have too few mature Type II cells, surfactant runs short, alveoli collapse, and RDS results.
Eliminating the rest: Type I cells only form the wall and do not secrete surfactant, so a Type I defect would not cause surfactant deficiency. Bronchial epithelium lies in the conducting airways, well above the alveoli, and plays no role in surfactant production. So option d is wrong because there clearly is a defective cell type. The answer is Type 2 pneumocytes.
Why Type 2 is correct: Surfactant is mostly dipalmitoylphosphatidylcholine (DPPC / lecithin). It acts like a detergent and keeps alveoli open by reducing surface tension. Premature or sick infants have too few mature Type II cells, surfactant runs short, alveoli collapse, and RDS results.
Eliminating the rest: Type I cells only form the wall and do not secrete surfactant, so a Type I defect would not cause surfactant deficiency. Bronchial epithelium lies in the conducting airways, well above the alveoli, and plays no role in surfactant production. So option d is wrong because there clearly is a defective cell type. The answer is Type 2 pneumocytes.
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