Biology – The gas exchange system | e-Consult

Surfactant is a lipoprotein substance produced by Type II pneumocytes within the alveoli. Its primary role is to reduce the surface tension of the fluid lining the alveoli. Surface tension is the force that causes the alveoli to collapse, particularly at the end of exhalation.

Importance of Surfactant: Without surfactant, the alveoli would tend to collapse during exhalation, significantly reducing the surface area available for gas exchange. This collapse would impair the efficiency of gas exchange, making it difficult to obtain sufficient oxygen and remove carbon dioxide. Surfactant reduces surface tension by inserting itself between the water molecules in the alveoli, disrupting the cohesive forces that cause them to attract each other. This allows the alveoli to remain open and inflated, maintaining a large surface area for gas exchange.

Consequences of Surfactant Deficiency: Neonatal Respiratory Distress Syndrome (NRDS), also known as hyaline membrane disease, is a condition that occurs in premature infants due to a deficiency of surfactant. In infants with NRDS, the alveoli collapse during exhalation, leading to:

• Increased Respiratory Effort: The infant has to work harder to breathe to keep the alveoli open.
• Reduced Oxygen Uptake: The reduced surface area for gas exchange leads to inadequate oxygen uptake.
• Increased Carbon Dioxide Retention: Inefficient carbon dioxide removal leads to a buildup of carbon dioxide in the blood.
• Potential Lung Damage: Prolonged respiratory distress can damage the lungs.

Treatment for NRDS typically involves administering artificial surfactant to help keep the alveoli open.