Select the incorrect statement.

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 of selecting the incorrect statement regarding the partial pressures of oxygen (O2) and carbon dioxide (CO2) in the lungs and venous blood, we will analyze each statement step by step.

### Step 1: Understand the Partial Pressures in the Lungs
- In the lungs, the partial pressure of oxygen (O2) is approximately 104 mmHg, which is relatively high.
- The partial pressure of carbon dioxide (CO2) in the lungs is lower, around 35 to 45 mmHg.

**Hint:** Remember that the lungs are where gas exchange occurs; O2 is taken in and CO2 is expelled.

### Step 2: Understand the Partial Pressures in Venous Blood
- In venous blood, the partial pressure of CO2 is higher, approximately 46 mmHg, because it is a waste product from cellular respiration.
- The partial pressure of O2 in venous blood is lower than in the lungs, typically around 30-40 mmHg.

**Hint:** Consider how blood carries gases; venous blood returns from tissues where it has released O2 and taken up CO2.

### Step 3: Analyze Each Statement
1. **Statement 1:** "The partial pressure of CO2 is higher in the air inside the lungs as compared to the venous blood."
- This statement is incorrect because the CO2 level in the lungs is lower than in venous blood.

2. **Statement 2:** "The partial pressure of O2 is higher in the air inside the lungs."
- This statement is correct as the lungs have a high concentration of O2.

3. **Statement 3:** "The partial pressure of O2 is lower inside the venous blood than in the air in the lungs."
- This statement is also correct since venous blood has less O2 than the air in the lungs.

4. **Statement 4:** "The partial pressure of CO2 is higher inside the venous blood than in air."
- This statement is correct because the air contains much less CO2 than venous blood.

### Conclusion
The incorrect statement is **Statement 1**, which claims that the partial pressure of CO2 is higher in the air inside the lungs compared to venous blood.

**Final Answer:** The incorrect statement is: "The partial pressure of CO2 is higher in the air inside the lungs as compared to the venous blood."