RAAS is a system involving Many organs . Which of these statements about RAAS is false ?

Options

A. It operates in response to decrease in blood pressure or blood volume
B. The JG cells release an enzyme renin which converts angiotensinogen into a peptide angiotensin ,l
C. Angiotensin II inhibits the release of aldosterone from adrenal gland
D. Angiotensin II increases blood pressure by causing arterioles to constrict

Answer

To solve the question regarding the Renin-Angiotensin-Aldosterone System (RAAS) and identify the false statement, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the RAAS System**:
- The Renin-Angiotensin-Aldosterone System (RAAS) is a hormone system that regulates blood pressure and fluid balance. It involves several organs, including the kidneys, adrenal glands, and blood vessels.

2. **Identify the Trigger for RAAS Activation**:
- RAAS is activated in response to a decrease in blood pressure or blood volume. This is crucial for understanding how the system functions.

3. **Role of Juxtaglomerular (JG) Cells**:
- Juxtaglomerular cells in the kidneys release the enzyme renin when they detect a drop in blood pressure or blood volume.

4. **Conversion of Angiotensinogen**:
- Renin converts angiotensinogen (a protein produced by the liver) into angiotensin I.

5. **Conversion of Angiotensin I to Angiotensin II**:
- Angiotensin I is then converted to angiotensin II by the action of the angiotensin-converting enzyme (ACE), primarily in the lungs.

6. **Effects of Angiotensin II**:
- Angiotensin II is a potent vasoconstrictor, which means it narrows blood vessels, leading to an increase in blood pressure.
- It also stimulates the adrenal cortex to release aldosterone.

7. **Function of Aldosterone**:
- Aldosterone promotes sodium reabsorption in the kidneys, which helps to increase blood volume and, consequently, blood pressure.

8. **Identify the False Statement**:
- The statement that angiotensin II "inhibits the release of aldosterone" is false. In reality, angiotensin II stimulates the release of aldosterone.

### Conclusion:
The false statement regarding the RAAS system is that angiotensin II inhibits the release of aldosterone from the adrenal gland. The correct understanding is that it actually stimulates aldosterone release.