Renin-angiotensin pathway mainly controls

Options

A. ultrafiltration
B. cardiac output
C. blood pressure
D. glucose reabsorption

Answer

### Step-by-Step Solution:

1. **Understanding the Renin-Angiotensin Pathway**: The Renin-Angiotensin System (RAS) is a hormone system that regulates blood pressure and fluid balance in the body. It involves the secretion of renin, an enzyme produced by the juxtaglomerular apparatus in the kidneys.

2. **Role of Juxtaglomerular Apparatus (JGA)**: The JGA detects decreases in blood pressure or blood volume. When it senses a drop, it releases renin into the bloodstream.

3. **Conversion Process**: Renin acts on angiotensinogen, a protein produced by the liver, converting it into angiotensin I. Angiotensin I is then converted into angiotensin II by the action of the angiotensin-converting enzyme (ACE), primarily in the lungs.

4. **Effects of Angiotensin II**: Angiotensin II has several effects that contribute to increasing blood pressure:
- It stimulates the adrenal cortex to release aldosterone, which promotes sodium and water reabsorption in the kidneys, increasing blood volume.
- It causes vasoconstriction, which narrows blood vessels and raises blood pressure.

5. **Conclusion**: The primary function of the renin-angiotensin pathway is to control blood pressure. Therefore, the correct answer to the question is that the Renin-Angiotensin pathway mainly controls **blood pressure**.

### Final Answer:
The Renin-Angiotensin pathway mainly controls **blood pressure** (Option 3).

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