Select the incorrect statement with respect to the partial pressure

Options

A. The partial pressure of `CO_2(pCO_2)` is higher in the air inside the lungs as compared to venous blood
B. The partial pressure of `O_2(pO_2)` is higher in the air inside the lungs as compared to venous blood
C. The partial pressure of `O_2(pO_2)` is lower inside the venous blood than in the air in the lung
D. The partial pressure of `CO_2(pCO_2)` is higher inside the venous blood than in the air

Answer

To solve the question regarding the incorrect statement about the partial pressure of gases, we will analyze each statement provided in the question step-by-step.

### Step 1: Understand Partial Pressure
Partial pressure refers to the pressure exerted by a single type of gas in a mixture of gases. It is important to know the typical values of partial pressures for gases like oxygen (O2) and carbon dioxide (CO2) in different locations of the body, such as the lungs and venous blood.

### Step 2: Analyze Each Statement

1. **Statement 1**: "Partial pressure of carbon dioxide is higher in the air inside the lungs."
- In the lungs, the typical partial pressure of CO2 is around 40 mmHg. In venous blood, it is approximately 45 mmHg. Therefore, this statement is incorrect because the partial pressure of CO2 in the lungs is lower than in venous blood.

2. **Statement 2**: "Partial pressure of oxygen is higher in the air inside the lungs."
- The partial pressure of oxygen in the lungs is about 104 mmHg, while in venous blood it is around 45 mmHg. This statement is correct.

3. **Statement 3**: "Partial pressure of oxygen is lower inside the venous blood."
- As mentioned, the partial pressure of oxygen in venous blood is indeed lower (45 mmHg) compared to that in the lungs (104 mmHg). This statement is also correct.

4. **Statement 4**: "Partial pressure of carbon dioxide is higher inside the venous blood."
- The partial pressure of CO2 in venous blood is 45 mmHg, which is higher than the CO2 level in the air (0.3 mmHg) and also higher than in the alveoli (40 mmHg). This statement is correct.

### Conclusion
After analyzing all the statements, we find that the first statement is incorrect. Therefore, the answer to the question is:

**The incorrect statement is: "Partial pressure of carbon dioxide is higher in the air inside the lungs."**