Surfactant

Question 1

Explain how a deficiency of type II alveolar cells leads to respiratory distress syndrome in prematurely born babies

Answer 1

1. Surfactant is made of amphiphatic molecules & reduces surface tension of fluid by modifying the forces @ the interfacial region
2. Lines alveolar epithelium & reduces tension of fluid lining the alveoli
3. Secreted by type II alveolar cells; is a vital component for lungs to expand properly
4. Main component is DPPC (a phospholipid)
5. Sphingomyelin synthesis shifts to DPPC synthesis by type II cells @ 32 weeks of IUL
6. Lung maturity is decided when DPPC: Sphingomyelin ratio is ↑ than 2
7. Severe lack of surfactant due to lack of synthesis of DPPC so lungs do not mature, and no means to reduce surface tension of fluid lining the alveoli
8. Lungs cannot be expanded; fluid will be retained; alveoli will collapse; causes IRDS

Question 2

Explain the biochemical basis of giving steroid injections to improve IRDS in pre-term babies

Answer 2

1. Steroid injections in pregnancy for mothers at risk of preterm delivery
2. Enhances fetal lung maturation by stimulating surfactant production (improving lung structure)
3. These effects collectively reduce the incidence and severity of respiratory distress syndrome in pre-term babies (improving their respiratory outcomes after birth)