RUHS, Jaipur, M.Sc Nu…: Renin is a \ \ \ \ \ \ produced by the \ \ \ \ \ \

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2024

Applied Physiology

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2024

Explanation

Renin is functionally classified as a proteolytic enzyme (an aspartyl protease) because it catalyzes the breakdown of a protein.
It is synthesized, stored, and secreted by the juxtaglomerular cells located in the afferent arterioles of the kidneys.
Renin's primary role is to initiate the Renin-Angiotensin-Aldosterone System (RAAS) by acting on its substrate, angiotensinogen.
This enzymatic action converts angiotensinogen (from the liver) into angiotensin I, which is the first step in a cascade that regulates blood pressure.

Option A: This is incorrect on both counts. Renin is an enzyme, not a hormone, and it is produced by the kidneys. The liver is the source of angiotensinogen, the substrate that renin acts upon.
Option B: While renin is produced by the kidney, it is functionally an enzyme, not a hormone. Hormones typically bind to receptors to exert a direct effect, whereas renin acts as a catalyst to modify another molecule.
Option C: Although renin is an enzyme, it is produced by the kidneys, not the liver. The liver produces many other enzymes and proteins, including angiotensinogen, but not renin.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiology of the Renin-Angiotensin-Aldosterone System (RAAS) as background academic context rather than a clinical decision trigger.
The RAAS pathway is a primary target for many antihypertensive medications, including ACE inhibitors (e.g., lisinopril), Angiotensin II Receptor Blockers (ARBs, e.g., losartan), and direct renin inhibitors (e.g., aliskiren).
Nurses must monitor blood pressure, serum potassium levels (risk of hyperkalemia), and renal function (BUN, creatinine) for patients on RAAS-inhibiting drugs.
Understanding this pathway is crucial for managing patients with hypertension, heart failure, and chronic kidney disease.

How to Approach the Question

First, break down the question. It asks for two pieces of information about renin: its biochemical classification (substance type) and its organ of origin.
Consider the first blank: 'Hormone' vs. 'Enzyme'. Recall that renin's job is to act on and change another molecule (angiotensinogen). This catalytic action is the defining characteristic of an enzyme.
Consider the second blank: 'liver' vs. 'kidney'. Recall that the renin-angiotensin system is a key mechanism for the kidneys to regulate blood pressure. Therefore, the kidney is the source of renin.
Combine the two correct pieces of information: Renin is an 'enzyme' produced by the 'kidney'.
Select the option that matches this conclusion.

Concept Tested & Keywords

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E6 Pharmacology Katzung 16e pp. 472-474, 473-475