Partial pressure of `O_2` in alveoli is

Options

A. 45 mm Hg
B. 104 mm Hg
C. 159 mm Hg
D. 50 mm Hg

Answer

To determine the partial pressure of O2 in the alveoli, follow these steps:

### Step-by-Step Solution:

1. **Understand Partial Pressure**:
- Partial pressure refers to the pressure exerted by a single gas in a mixture of gases. It is an important concept in understanding gas exchange in the lungs.

2. **Identify the Context**:
- The question specifically asks for the partial pressure of O2 in the alveoli. The alveoli are the small air sacs in the lungs where gas exchange occurs.

3. **Recall Normal Values**:
- In a healthy human, the typical partial pressure of O2 in the alveoli is approximately 104 mmHg. This value can vary slightly based on factors such as altitude and health conditions.

4. **Evaluate the Options**:
- The options provided are 45 mmHg, 104 mmHg, 59 mmHg, and 50 mmHg.
- Comparing these options with the known value of 104 mmHg, we can see that 104 mmHg is the correct answer.

5. **Conclusion**:
- Therefore, the partial pressure of O2 in the alveoli is **104 mmHg**.

### Final Answer:
The partial pressure of O2 in the alveoli is **104 mmHg**.

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