Predominant constituent of hyaline membrane is
**Core Concept**
Hyaline membrane disease, also known as respiratory distress syndrome (RDS), is a condition that affects newborns, particularly those born prematurely. It occurs due to a deficiency of surfactant in the lungs, leading to alveolar collapse and respiratory distress. The hyaline membrane is a characteristic feature of this disease, and it forms in the alveoli due to the presence of cellular debris and surfactant.
**Why the Correct Answer is Right**
The predominant constituent of the hyaline membrane is phospholipid, specifically phosphatidylcholine, which is a major component of surfactant. Surfactant is a complex mixture of phospholipids, neutral lipids, and proteins that reduces surface tension in the lungs, facilitating easy lung expansion during breathing. The absence of sufficient surfactant in the lungs leads to increased surface tension, resulting in alveolar collapse and the formation of hyaline membranes.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is not a known constituent of hyaline membranes. While cellular debris and other substances may be present, phospholipid is the primary component.
* **Option B:** This option is incorrect because it is not a specific enough answer. While cellular debris may be present in hyaline membranes, it is not the predominant constituent.
* **Option C:** This option is incorrect because it is not a known constituent of hyaline membranes. While proteins may be present in surfactant, they are not the primary component of hyaline membranes.
**Clinical Pearl / High-Yield Fact**
Surfactant replacement therapy is a life-saving treatment for hyaline membrane disease, and it involves the administration of exogenous surfactant to reduce surface tension in the lungs and improve lung function.
**Correct Answer:** C.