Juxta-glomerular cells form

Options

A. Angiotensinogen and angiotensin
B. Renin and erythropoietin
C. Counter-current
D. Selective secretory and absorptive apparatus.

Answer

### Step-by-Step Solution:

1. **Understanding Juxtaglomerular Cells**:
- Juxtaglomerular cells are specialized cells located in the kidneys, specifically in the juxtaglomerular apparatus (JGA). This apparatus is formed at the junction where the afferent arteriole meets the distal convoluted tubule (DCT).

2. **Function of Juxtaglomerular Cells**:
- The primary function of juxtaglomerular cells is to regulate blood pressure and blood volume. They do this by secreting a hormone called renin when blood pressure decreases.

3. **Renin-Angiotensin-Aldosterone System (RAAS)**:
- Renin acts on angiotensinogen, an inactive protein produced by the liver, converting it into angiotensin I. Angiotensin I is then converted into angiotensin II, primarily in the lungs.

4. **Effects of Angiotensin II**:
- Angiotensin II has two main effects:
- It stimulates the adrenal cortex to release aldosterone, which increases the reabsorption of sodium and water in the kidneys, thus increasing blood volume and pressure.
- It causes vasoconstriction of blood vessels, which also helps to raise blood pressure.

5. **Conclusion**:
- Therefore, juxtaglomerular cells primarily form the hormone **renin**, which is crucial for the regulation of blood pressure through the RAAS.

### Final Answer:
Juxtaglomerular cells form **renin**.

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