Renin is released from JGA in response to

Options

A. High glomerular blood pressure
B. Fall in glomerular blood flow
C. High GFR
D. Decrease in osmolarity

Answer

**Step-by-Step Solution:**

1. **Understanding Renin and JGA**: Renin is an enzyme that is released by the Juxtaglomerular Apparatus (JGA) in the kidneys. The JGA plays a crucial role in regulating blood pressure and fluid balance.

2. **Analyzing the Options**:
- **Option 1: High Glomerular Blood Pressure**: This option suggests that renin is released in response to high blood pressure. However, this is incorrect because high blood pressure actually inhibits the secretion of renin.

- **Option 2: Fall in the Glomerular Blood Flow**: This option indicates that a decrease in blood flow to the glomeruli triggers the release of renin. This is correct; when blood flow decreases, the JGA detects this change and releases renin to help increase blood pressure and restore blood flow.

- **Option 3: High GFR (Glomerular Filtration Rate)**: This option states that a high GFR leads to renin release. This is incorrect because a high GFR would not stimulate renin secretion.

- **Option 4: Decrease in Osmolarity**: This option suggests that a decrease in osmolarity triggers renin release. This is also incorrect, as renin release is not directly stimulated by changes in osmolarity.

3. **Conclusion**: After analyzing all the options, the correct answer is **Option 2: Fall in the Glomerular Blood Flow**. This is the primary stimulus for the release of renin from the JGA.