In human body, the action of surfactant is done by
💡 Explanation
## **Core Concept**
The core concept being tested here is the role of surfactant in the human body, specifically in the lungs. Surfactant is a critical substance that reduces surface tension in the alveoli, facilitating easier lung expansion during breathing.
## **Why the Correct Answer is Right**
The correct answer, **D. Dipalmitoylphosphatidylcholine (DPPC)**, is a type of phospholipid that is the main component of pulmonary surfactant. DPPC works by forming a monolayer at the air-liquid interface in the alveoli, significantly reducing surface tension. This reduction in surface tension prevents the collapse of alveoli during expiration, thereby decreasing the work of breathing and facilitating lung expansion. The presence of DPPC is crucial for normal lung function, especially in newborns.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is blank and does not provide any information to evaluate its accuracy.
- **Option B:** This option is also blank and cannot be assessed.
- **Option C:** Similarly, this option does not provide any information and is incorrect by default.
## **Clinical Pearl / High-Yield Fact**
A critical clinical pearl related to surfactant and DPPC is that **neonatal respiratory distress syndrome (NRDS)** is often caused by a deficiency of surfactant, particularly DPPC, in premature infants. This condition can lead to significant morbidity and mortality. Administering exogenous surfactant has become a standard treatment for NRDS, highlighting the importance of DPPC in lung physiology.