Surfactant

Options

A. Protein produced by type II alveolar cells
B. Excessivein many premature infants causing difficulty in breathing
C. Decrease surface tension of fliuid lining alveoli
D. Lacking in individualssuffering from acute respiratory distress syndromes

Explanation

### Step-by-Step Solution:

1. **Understanding Surfactant**: Surfactant is a substance that reduces surface tension in the lungs. It is primarily composed of lipids and proteins and is secreted by type II alveolar cells.

2. **Location of Surfactant**: Surfactant is found in the alveoli, which are tiny air sacs in the lungs where gas exchange occurs. It plays a crucial role in maintaining the stability of these air sacs.

3. **Function of Surfactant**: The main function of surfactant is to lower the surface tension at the air-liquid interface within the alveoli. This reduction in surface tension prevents the alveoli from collapsing and facilitates easier breathing.

4. **Identifying the Correct Option**: Among the options provided:
- Option 1: Protein produced by type 2 alveolar cells - This is true but does not directly describe surfactant's function.
- Option 2: Excessive N. Mane premature infants causing difficulty in breathing - This is related to surfactant deficiency but is not a definition.
- Option 3: Decreased surfactant of fluid lining alveolar - This option correctly describes the role of surfactant in reducing surface tension.
- Option 4: Lacking in individuals suffering from acute respiratory distress syndrome - This is also true but does not define surfactant.

5. **Conclusion**: The most accurate description of surfactant's role is the decrease in surface tension of the fluid lining the alveoli, which is critical for normal respiratory function.

### Final Answer:
The correct option is **Option 3: Decreased surfactant of fluid lining alveolar**.

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