Question

Why is the activity of juxtaglomerular (JG) cells required?

• A. To increase blood glucose levels
• B. To regulate blood pressure and blood volume
• C. To reabsorb urea from urine
• D. To digest proteins in the stomach

Hint:

JG Cells $\rightarrow$ Renin Secretion $\rightarrow$ RAAS Activation $\rightarrow$ Increased Blood Pressure and Blood Volume.

Answer 1

The Correct Option is B

Concept: Juxtaglomerular (JG) cells are specialized smooth muscle cells located in the walls of the afferent arteriole near the glomerulus of the nephron. These cells play a crucial role in maintaining blood pressure and blood volume through the renin-angiotensin-aldosterone system (RAAS).

Step 1: Location of JG Cells
JG cells are found in close association with the glomerulus and form part of the juxtaglomerular apparatus (JGA).

Step 2: Function of JG Cells
Whenever blood pressure falls, JG cells secrete renin. Renin initiates a hormonal cascade that eventually increases blood pressure and blood volume.

Step 3: Evaluate Other Options
Blood glucose regulation is mainly controlled by insulin and glucagon. Urea reabsorption occurs in kidney tubules and is not the primary function of JG cells. Protein digestion occurs in the stomach through enzymes such as pepsin. Thus, Options (A), (C), and (D) are incorrect. Conclusion: JG cells are required for maintaining normal blood pressure and blood volume. \[ \boxed{\text{(B) To regulate blood pressure and blood volume}} \]