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Pulmonary surfactant metabolism
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Pulmonary surfactant is a mix of phospholipids, which are a type of fat, and proteins. It lines the lung tissue from the inside and lowers surface tension, the force with which a wet surface tends to stick to itself. Because of that, the alveoli, the little sacs where air delivers oxygen, do not close when you breathe out. Without that film, the wet walls of the alveolus stick together as it empties.
It is made by type two pneumocytes, which are cells of the alveolus itself. They build it in the endoplasmic reticulum, the cell's internal factory, and store it packaged in small sacs called lamellar bodies. From there it is released. Production starts around 26 weeks of pregnancy and reaches mature levels at about 35.
Several genes take part in making it, among them SFTPB, SFTPC, and ABCA3. When one of them carries a mutation, surfactant dysfunction appears, and in its most severe form it causes respiratory distress in the newborn.
In brief
Pulmonary surfactant combines phospholipids and proteins, coats the lung and lowers surface tension, preventing alveolar collapse.
Without that film, the wet walls of the alveolus stick together as it empties.
Type two pneumocytes build it in their endoplasmic reticulum, package it into lamellar bodies, and release it; production begins around 26 weeks of gestation and reaches mature levels around 35 weeks.
Mutations in SFTPB, SFTPC, and ABCA3 cause surfactant dysfunction; in its most severe form it causes respiratory distress in the newborn.
Sources (2)
- MedlinePlus Genetics, U.S. National Library of MedicineSurfactant dysfunction, MedlinePlus GeneticsPublished
- National Center for Biotechnology Information, StatPearls PublishingSurfactant, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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