Which one represents pulmonary circulation ?

Options

A. Left auricle (oxygenated blood `to` lungs (deoxygenated blood `to` Right auricle
B. Left auricle (deoxygenated blood `to` lungs (oxygenated blood `to` Right auricle
C. Left auricle (oxygenated blood `to` lungs (deoxygenated blood `to` left auricle
D. Right auricle (deoxygenated blood `to` lungs (oxygenated blood `to` Left auricle

Answer

To solve the question "Which one represents pulmonary circulation?", we will break down the concept of pulmonary circulation step by step.

### Step-by-Step Solution:

1. **Understanding Pulmonary Circulation**:
- Pulmonary circulation refers to the movement of blood between the heart and the lungs. It specifically involves the transport of deoxygenated blood to the lungs for oxygenation and the return of oxygenated blood back to the heart.

2. **Identifying the Pathway**:
- Deoxygenated blood from the body returns to the heart through the superior and inferior vena cava into the right atrium (right auricle).
- From the right atrium, the blood flows into the right ventricle.

3. **Blood Flow to the Lungs**:
- The right ventricle pumps the deoxygenated blood into the pulmonary artery, which carries it to the lungs.
- In the lungs, carbon dioxide is exchanged for oxygen in the blood.

4. **Return of Oxygenated Blood**:
- After oxygenation, the blood returns to the heart via the pulmonary veins into the left atrium (left auricle).
- This oxygenated blood is then pumped from the left atrium to the left ventricle and subsequently distributed to the rest of the body.

5. **Identifying the Correct Option**:
- Based on the flow described, the correct representation of pulmonary circulation is:
- Right atrium → Right ventricle → Lungs → Left atrium.
- Therefore, the option that states "right auricle (deoxygenated blood) to lungs (oxygenated blood) to left auricle" accurately represents pulmonary circulation.

### Conclusion:
The correct answer to the question is **Option 4: Right auricle to lungs, then lungs to left auricle**.