QS Study

Mechanism of action of the Surfactant

The surfactant is a phospholipid. It had a hydrophilic head and hydrophobic tail lining the alveoli with their tail facing the lumen. They prevent air water intrance and adhesion of water molecule and in this way prevent the surface tension.

The mechanism of action of surfactant breaks the structure of water in the alveoli, as the presence of surfactant makes sure the water molecules are unable to aggregate and form a surface film. As a surface film of water doesn’t form, it is unable to contract and make alveoli collapse

The main function of surfactant is to lower the surface tension at the air/liquid interface within the alveoli of the lung. It is produced in the lungs to facilitate them to develop usually. It reduces the surface tension of the alveoli to avert collapse. A preterm infant is often born with less than 10% the surfactant of a term neonate which makes breathing complex, diminishes oxygenation, and can lead to further lung injury.

Fig: an action of the surfactant

Hyaline membrane disease

It is the severe impairment of the function of a respiratory system of the premature baby.

Cause: Inadequate secretion of lung surfactant.


(1) The surface tension of the lung alveoli is high,

(2) Many alveoli remain collapse,

(3) Decrease the lung compliance,

(4) Severe hypoxia develop.