The group of modified cells lying adjacent to the afferent and efferent arterioles is called?

JIPMER Nursing Officer-2024

Applied Anatomy

Easy

Appeared in: JIPMER Nursing Officer-2024

Explanation

The juxtaglomerular apparatus (JGA) is a specialized structure located at the vascular pole of the glomerulus.
It is composed of modified cells from both the distal convoluted tubule (macula densa) and the afferent arteriole (juxtaglomerular cells).
This unique anatomical arrangement allows the JGA to monitor tubular fluid composition and blood pressure.
Its primary function is to regulate systemic blood pressure and the glomerular filtration rate through the release of renin.

Option A: The renal corpuscle is the filtration unit of the nephron, consisting of the glomerulus and Bowman's capsule. It is not the specific group of regulatory cells mentioned.
Option C: The peritubular network is a system of capillaries surrounding the renal tubules, primarily involved in reabsorption and secretion, not blood pressure regulation at the vascular pole.
Option D: The vasa recta are specialized capillaries located in the medulla, associated with the Loop of Henle. They are crucial for concentrating urine, not located near the afferent/efferent arterioles in the cortex.

Visual 1: Diagram of the Nephron - A detailed illustration showing the renal corpuscle, proximal tubule, Loop of Henle, and distal tubule, with a magnified inset of the juxtaglomerular apparatus. The inset should clearly label the afferent arteriole, efferent arteriole, macula densa, and juxtaglomerular cells to show their proximity.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy and physiology of the nephron, specifically the juxtaglomerular apparatus as background academic context rather than a clinical decision trigger.
The JGA is the starting point of the Renin-Angiotensin-Aldosterone System (RAAS), a critical pathway for blood pressure regulation. When JG cells detect low blood pressure, they release renin, initiating a cascade that leads to vasoconstriction and sodium/water retention, ultimately increasing blood pressure.
Many antihypertensive medications, such as ACE inhibitors (e.g., Ramipril) and Angiotensin II Receptor Blockers (ARBs) (e.g., Losartan), directly target the RAAS pathway initiated by the JGA.
A nurse must understand the function of the JGA to appreciate why a patient with renal artery stenosis (narrowing of the artery to the kidney) often develops severe hypertension. The stenosis reduces blood flow to the JGA, which misinterprets it as low systemic blood pressure and chronically overproduces renin.

How to Approach the Question

This is a factual recall question based on renal anatomy.
First, identify the key anatomical terms in the question: 'modified cells,' 'adjacent,' 'afferent and efferent arterioles.' This points to a specific micro-structure within the kidney.
Mentally visualize the structure of a nephron, focusing on the area where the blood vessels enter and leave the glomerulus (the vascular pole).
Recall the names of the structures located in this specific region.
Differentiate the functions of the options: The renal corpuscle filters, the peritubular network reabsorbs/secretes, the vasa recta concentrates urine, and the juxtaglomerular apparatus regulates. The question describes the regulatory structure.

Concept Tested & Keywords

Concept Tested: Anatomy and physiology of the nephron, specifically the juxtaglomerular apparatus.
Stem keywords: modified cells, adjacent, afferent and efferent arterioles
Lead-in keywords: is called

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