Partial pressure of oxygen in the lungs is .

Options

A. 100 mm Hg
B. 110 mm Hg
C. 40 mm Hg
D. 60 mm Hg

Answer

To determine the partial pressure of oxygen in the lungs, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Partial Pressure**:
- Partial pressure refers to the pressure exerted by a single type of gas in a mixture of gases. In the context of the lungs, we are specifically looking at the partial pressure of oxygen (O2).

2. **Identify the Relevant Context**:
- In the lungs, oxygen is exchanged between the alveoli and the blood. The partial pressure of oxygen in the alveoli is crucial for understanding how oxygen moves into the bloodstream.

3. **Know the Normal Values**:
- The normal partial pressure of oxygen in the alveoli (and thus in the pulmonary venous blood) is approximately 100 mmHg. This value is essential for efficient oxygen transport in the body.

4. **Evaluate the Options**:
- Given options are:
- a) 100 mmHg
- b) 110 mmHg
- c) 40 mmHg
- d) 60 mmHg
- From the information above, we can conclude:
- a) 100 mmHg is correct.
- b) 110 mmHg is incorrect (too high).
- c) 40 mmHg is incorrect (this is the partial pressure in deoxygenated blood).
- d) 60 mmHg is incorrect (this is also not the standard value for oxygenated blood).

5. **Conclusion**:
- The correct answer is **100 mmHg**, which is the partial pressure of oxygen in the lungs.