AIIMS Nagpur NO - 2018: Regulation of pH within the body is done by?

AIIMS Nagpur NO - 2018

Applied Physiology

Easy

Appeared in: AIIMS Nagpur NO - 2018

Explanation

The kidneys are the most powerful system for long-term regulation of blood pH.
They maintain acid-base balance by selectively excreting or reabsorbing hydrogen ions (H+) and bicarbonate ions (HCO3−).
In acidosis (excess acid), the kidneys excrete H+ and conserve HCO3− to raise the pH back to normal.
In alkalosis (excess base), the kidneys excrete HCO3− and retain H+ to lower the pH back to normal.
This renal mechanism provides a permanent solution to acid-base disturbances, unlike the temporary actions of buffers and the respiratory system.

Option A: The spleen's primary functions are related to the immune system and filtering blood; it has no direct role in regulating the body's acid-base balance.
Option B: The liver has an indirect, metabolic role in acid-base balance (e.g., metabolism of amino acids and organic acids, which can produce or consume acid) but is not a primary, direct regulator of blood pH like the kidneys.
Option C: The heart is a muscular pump responsible for circulating blood throughout the body. It does not have a direct physiological function in regulating pH.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiological mechanisms of acid-base balance as background academic context rather than a clinical decision trigger.
Nurses must monitor renal function (e.g., BUN, creatinine, urine output) in patients with acid-base imbalances like metabolic acidosis or alkalosis, as kidney failure severely impairs the body's ability to compensate.
The normal pH of arterial blood is tightly controlled between 7.35 and 7.45. Deviations outside this range can disrupt cellular functions and be life-threatening.
What if? If a patient has chronic kidney disease (CKD), their ability to excrete acid is diminished. This often leads to chronic metabolic acidosis, which requires careful management, dietary changes, and sometimes alkali therapy (like sodium bicarbonate) to prevent complications.

How to Approach the Question

First, identify the core physiological process asked in the question, which is the 'Regulation of pH'.
Next, review the options provided: Spleen, Liver, Heart, and Kidney. These are all major organs.
Recall the primary function of each organ. Spleen is for immunity/blood filtration, Liver for metabolism/detoxification, and Heart for pumping blood.
Recall the body's main acid-base regulation systems. The key systems are the lungs (for rapid, short-term control via CO2) and the kidneys (for slow, long-term, and powerful control via H+ and HCO3-).
Compare the functions with the options. The kidney is the only organ listed that serves as a primary regulator of acid-base balance.
Therefore, select Kidney as the correct answer.

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