Angiotensinogen is a protein produced and secreted by

Options

A. juxtaglomerular (JG) cells
B. macula densa cells
C. endothelial cells (cells lining the blood vessels)
D. liver cells.

Answer

**Step-by-Step Solution:**

1. **Understanding Angiotensinogen**: Angiotensinogen is a protein that plays a crucial role in the regulation of blood pressure and fluid balance in the body. It is classified as a plasma protein.

2. **Source of Angiotensinogen**: The question asks where angiotensinogen is produced and secreted. The options provided include:
- Juxtaglomerular cells
- Macula densa cells
- Endothelial cells
- Liver cells

3. **Identifying the Correct Source**:
- **Juxtaglomerular Cells**: These cells are responsible for secreting the enzyme renin, which converts angiotensinogen into angiotensin I. However, they do not produce angiotensinogen itself.
- **Macula Densa Cells**: These cells are part of the juxtaglomerular apparatus and are involved in sensing sodium concentration but do not produce angiotensinogen.
- **Endothelial Cells**: These cells line the blood vessels and are not involved in the production of angiotensinogen.
- **Liver Cells**: The liver is known for synthesizing various plasma proteins, including angiotensinogen. It consists of approximately 453 amino acids.

4. **Conclusion**: Based on the information, the correct answer is that angiotensinogen is produced and secreted by liver cells.

**Final Answer**: Angiotensinogen is a protein produced and secreted by liver cells.

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