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 long-term regulators of acid-base balance in the body.
They maintain blood pH within the narrow range of 7.35-7.45 by controlling the excretion of acids (hydrogen ions, H⁺) and the reabsorption of bases (bicarbonate, HCO₃⁻).
This renal mechanism provides a permanent solution to acid-base disturbances, unlike the temporary buffering by blood or the rapid but short-term adjustments by the respiratory system.
By producing urine that is typically more acidic (pH ~6.0) than blood (pH 7.4), the kidneys demonstrate their constant role in removing excess acid from the body.

Option A: The spleen's primary functions are related to the immune system (filtering pathogens) and hematology (removing old red blood cells). It does not have a direct role in regulating the body's acid-base balance.
Option B: The liver's role in pH balance is indirect. While metabolic processes in the liver, such as the urea cycle, can consume bicarbonate and affect pH, it is not a primary regulator. Its main functions are metabolism, detoxification, and protein synthesis.
Option C: The heart's function is to act as a pump, circulating blood throughout the body. It ensures that blood reaches the kidneys and lungs, which are the organs that actually regulate pH, but it does not perform the regulation itself.

Visual 1: Diagram: The renal tubule showing the secretion of H+ ions and reabsorption of HCO3- ions, illustrating the kidney's mechanism for pH control.
Visual 2: Flowchart: The three lines of defense for acid-base balance (Blood Buffers, Respiratory System, Renal System), showing their speed and duration of action.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiological regulation 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 critically ill patients, as impaired kidney function directly compromises the body's ability to correct acid-base imbalances like metabolic acidosis.
Understanding renal compensation is vital when interpreting Arterial Blood Gas (ABG) results. For example, in a patient with respiratory acidosis, an elevated bicarbonate level indicates the kidneys are working to compensate.
What if? If a patient has Chronic Kidney Disease (CKD), their ability to excrete the daily metabolic acid load is diminished. This leads to a state of chronic metabolic acidosis, which can cause muscle wasting, bone disease, and progression of kidney failure.

How to Approach the Question

This is a factual recall question testing core physiological knowledge.
First, identify the key process in the question stem: 'Regulation of pH'.
Next, systematically review the primary function of each organ listed in the options.
Spleen: Primarily an immune and blood-filtering organ.
Liver: Primarily a metabolic and detoxification organ.
Heart: Primarily a circulatory pump.

Concept Tested & Keywords

Q4YWzls5tg4pgNfbY8vZ8L