Which of the following is not a component of pulmonary circulation?

Options

A. Pulmonary vein
B. Pulmonary artery
C. Aorta
D. Heart

Answer

To determine which of the following is not a component of pulmonary circulation, let's analyze each option provided:

1. **Pulmonary Vein**: The pulmonary veins are responsible for carrying oxygenated blood from the lungs back to the heart. This is a crucial part of pulmonary circulation, as it connects the lungs to the heart after gas exchange occurs.

2. **Pulmonary Artery**: The pulmonary artery carries deoxygenated blood from the heart to the lungs. This is also a vital component of pulmonary circulation, as it is the pathway through which blood is sent to the lungs for oxygenation.

3. **Heart**: The heart is the central organ in the circulatory system and plays a significant role in pulmonary circulation by pumping blood to the lungs and receiving blood back from the lungs. Therefore, the heart is indeed a component of pulmonary circulation.

4. **Aorta**: The aorta is the largest artery in the body and is responsible for carrying oxygenated blood from the heart to the rest of the body. It does not play a role in pulmonary circulation, which is specifically concerned with the flow of blood to and from the lungs.

Based on this analysis, the correct answer is:

**Aorta** - This is not a component of pulmonary circulation.

### Step-by-Step Solution:
1. Identify the components of pulmonary circulation.
2. Analyze each option provided in the question.
3. Determine the role of each component in relation to pulmonary circulation.
4. Conclude which option does not belong to pulmonary circulation.