The main function of kidney is to

OSSSC Nursing Officer-2021

Applied Physiology

Easy

Appeared in: OSSSC Nursing Officer-2021

Explanation

The kidneys are the primary organs for maintaining homeostasis by controlling the volume and composition of body fluids.
A key function is filtering the blood to remove metabolic waste products, such as urea, creatinine, and uric acid.
They precisely regulate the body's water and electrolyte balance by adjusting excretion to match intake, which is crucial for stable blood pressure and cell function.

Option A: Eliminating oxygen is not a function of the kidneys. Oxygen is utilized by cells for metabolism, and excess is not 'eliminated' in this way. Gas exchange, including taking in oxygen and removing carbon dioxide, is the role of the lungs.
Option C: While the kidneys play a crucial role in activating Vitamin D to its hormonal form (calcitriol), the primary organ for the metabolism of a wide range of vitamins is the liver. This is not the main function of the kidneys.
Option D: The elimination of carbon dioxide, a waste product of cellular respiration, is a primary function of the lungs through the process of exhalation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Primary functions of the kidney as background academic context rather than a clinical decision trigger.
Nurses monitor kidney function by tracking urine output, which should be at least 30 mL/hour for an adult. Oliguria (urine output less than 500 ml/day) can be a sign of acute kidney injury.
Lab values such as Blood Urea Nitrogen (BUN) and serum creatinine are critical indicators of kidney function. Elevated levels suggest the kidneys are not filtering waste effectively.
Patient education is vital for individuals with chronic kidney disease (CKD). Nurses teach about dietary restrictions (e.g., low sodium, potassium, protein) and fluid intake limits to reduce the workload on the kidneys.

How to Approach the Question

First, identify the core subject of the question, which is the 'main function' of the 'kidney'.
Recall the basic physiological roles of major organs. The kidney is part of the urinary system.
Evaluate each option against your foundational knowledge. Option A (oxygen) and D (carbon dioxide) relate to the respiratory system (lungs).
Consider Option C (metabolize vitamins). While the kidney does activate Vitamin D, the liver is the primary site for general vitamin metabolism. This is a secondary, not main, function.
Option B directly addresses the two most well-known and critical roles of the kidney: managing fluids and clearing waste. This aligns with the definition of the urinary system's primary purpose.
Select the option that describes the most comprehensive and central role of the organ in question.

Concept Tested & Keywords

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