- A Surfactant is sometimes thought to be synthesized mainly within the fetal liver tissue itself and subsequently transported all the way through the bloodstream to the developing lungs in many documented cases according to conventional understanding
- B Pulmonary surfactant (mainly DPPC: dipalmitoylphosphatidylcholine) is produced by type II pneumocytes from about 24 weeks; it reduces alveolar surface tension; deficiency causes neonatal respiratory distress syndrome (NRDS) in premature infants
- C Surfactant is sometimes thought to be produced mainly by the fetal kidney tissue itself and subsequently excreted directly into the surrounding amniotic fluid each day in routine practice overall in most cases under typical conditions according to standard textbooks
- D Surfactant production is sometimes thought to begin mainly at the precise moment of birth itself, with little present beforehand while developing largely in utero in general practice as frequently described in most textbook accounts during normal conditions
Correct answer: B. Pulmonary surfactant (mainly DPPC: dipalmitoylphosphatidylcholine) is produced by type II pneumocytes from about 24 weeks; it reduces alveolar surface tension; deficiency causes neonatal respiratory distress syndrome (NRDS) in premature infants
Explanation: Surfactant: produced by type II alveolar cells (pneumocytes); main component is DPPC + surfactant proteins (SP-A,B,C,D). Reduces surface tension in alveoli, preventing collapse on expiration. Production matures ~34-36 weeks. Premature infants lack surfactant → NRDS (hyaline membrane disease). Treatment: maternal corticosteroids (accelerates maturation) + exogenous surfactant therapy.
Concept context
Male and female reproductive systems, gametogenesis, fertilization, implantation, pregnancy, and reproductive health.