JGA plays a complex regulatory role when

Options

A. (1) there is fall in glomerular blood pressure
B. (2) ADH secretion is maximum
C. (3) glucose level is high in blood
D. (4) vitamin C absorption is minimum

Answer

### Step-by-Step Solution:

1. **Understanding the Juxtaglomerular Apparatus (JGA)**:
- The Juxtaglomerular Apparatus (JGA) is a specialized structure located in the nephron, specifically at the junction of the afferent arteriole and the distal convoluted tubule.
- It consists of specialized cells that play a crucial role in regulating blood pressure and the glomerular filtration rate (GFR).

2. **Role of JGA in Blood Pressure Regulation**:
- The JGA is responsible for the secretion of renin, an enzyme that is crucial in the renin-angiotensin-aldosterone system (RAAS).
- When there is a decrease in blood pressure, the stretch receptors in the walls of the afferent arterioles detect this change and stimulate the JGA to release renin.

3. **Analyzing the Options**:
- **Option 1**: "There is a fall in the glomerular blood pressure" - This is correct as the JGA responds to low blood pressure by secreting renin.
- **Option 2**: "ADH secretion is maximum" - This is incorrect because while ADH (antidiuretic hormone) plays a role in water retention, it is not directly regulated by the JGA.
- **Option 3**: "Glucose level is high in blood" - This is also incorrect as glucose levels are not directly regulated by the JGA.
- **Option 4**: "Vitamin C absorption is minimum" - This is incorrect since the JGA does not regulate vitamin C absorption.

4. **Conclusion**:
- The correct answer is **Option 1: There is a fall in the glomerular blood pressure**. The JGA plays a complex regulatory role primarily in response to changes in blood pressure.