Definition
- Pulmonary surfactant is a phospholipid-rich lipoprotein film lining the alveolar epithelium.
- It lowers surface tension at the air-liquid interface and alters its effect with alveolar diameter.
- Principal surface-tension-lowering agent: dipalmitoylphosphatidylcholine (DPPC), also called dipalmitoyl-lecithin (DPL).
- Alveolar surface tension is inversely proportional to phospholipid concentration.
Composition
Composition of pulmonary surfactant
Component
Lipids
- Proportion
- 90%
- Detail
- DPPC 62%, phosphatidylglycerol 5%, other phospholipids 10%, neutral lipids 13%
Proteins
- Proportion
- 8%
- Detail
- Albumin, IgA, apoproteins SP-A, SP-B, SP-C, SP-D
Carbohydrates
- Proportion
- 2%
- Detail
- —