Question

Effect of Surfactant

5. What is the role of surfactant in respiration? Describe the anatomy involved. Often times

extremely premature babies are born without lung surfactant. What would happen to their lungs

and blood gases they were not given artificial surfactant at birth? Explain.

Answer 1

Surfactant is a lipoprotein which is synthesized by type 2 pneumocytes lining the alveoli and it appears during 28-32 weeks of intrauterine life. Major lipid portion is lecithin and minor portion is contributed by sphingomyelin. There are four protein subtypes found in surfactant, they are SPA,SPB,, SPC and SPD.

Function of surfactant in respiratory system -

a) it's main function is to reduce surface tension in the alveoli.

b) it stabilises the alveoli and maintain it's integrity.

c) it prevents alveoli from getting collapsed.

d) it has role in lung immunity as it is produced by type 2 pneumocytes which can be converted to the stem cells in need.

Hormones like cortisol and thyroid hormones increases the synthesis of surfactant whereas hormones like insulin decreased surfactant production.

In premature babies, surfactant production is poor as it appears during 28-30 weeks. If surfactant levels is reduced or very low, surface tension will be raised and alveoli will be collapsed and gas exchange will be compromised. If artificial surfactant is not given, it will lead to distress and baby will die.

Also, hyaline membrane disease is caused due to surfactant deficiency which is treated by the drug preparations containing molecules like surfactant. Most commonly used is lucinactant and beractant.

Thus, steroids such as dexamethasone or betamethasone are given in a pregnant women at risk of delivering premature babies to induce lung maturity as steroid induce surfactant release in lungs.