value of `pO_2` in deoxygenated blood is equal to value of `pCo_2` in

Options

A. systemic veins
B. systemic arteries
C. pulmonary arteries
D. atmosphere

Answer

To solve the question regarding the value of \( pO_2 \) in deoxygenated blood being equal to the value of \( pCO_2 \) in a certain type of blood, we will analyze the different types of blood vessels and their characteristics.

### Step-by-Step Solution:

1. **Understanding Deoxygenated Blood**:
- Deoxygenated blood is blood that has a low concentration of oxygen (\( pO_2 \)) and a high concentration of carbon dioxide (\( pCO_2 \)). This blood is typically found in systemic veins as it returns to the heart from the body.

2. **Identifying Blood Vessels**:
- We need to identify where the \( pO_2 \) in deoxygenated blood is equal to \( pCO_2 \). The options provided include systemic veins, systemic arteries, pulmonary arteries, and the atmosphere.

3. **Analyzing Systemic Veins**:
- Systemic veins carry deoxygenated blood back to the right atrium of the heart. In this blood, \( pO_2 \) is low, and \( pCO_2 \) is high. Thus, \( pO_2 \neq pCO_2 \) in systemic veins.

4. **Analyzing Systemic Arteries**:
- Systemic arteries carry oxygenated blood away from the heart to the body. In this blood, \( pO_2 \) is high, and \( pCO_2 \) is low. Therefore, \( pO_2 \neq pCO_2 \) in systemic arteries.

5. **Analyzing Pulmonary Arteries**:
- Pulmonary arteries carry deoxygenated blood from the right ventricle of the heart to the lungs. Here, the blood is still deoxygenated, meaning \( pO_2 \) is low and \( pCO_2 \) is high. Thus, \( pO_2 \neq pCO_2 \) in pulmonary arteries.

6. **Analyzing the Atmosphere**:
- The atmosphere contains a mixture of gases, primarily oxygen and nitrogen, with very little carbon dioxide. The values of \( pO_2 \) and \( pCO_2 \) in the atmosphere do not correlate with deoxygenated blood.

7. **Conclusion**:
- The only place where the value of \( pO_2 \) in deoxygenated blood is equal to the value of \( pCO_2 \) is in the **pulmonary arteries**. This is because the blood in the pulmonary arteries is deoxygenated and has a specific balance of gases as it travels to the lungs for oxygenation.

### Final Answer:
The value of \( pO_2 \) in deoxygenated blood is equal to the value of \( pCO_2 \) in **pulmonary arteries**.