Principal electrolyte of intracellular fluid compartment is? & x20; - RUHS, Jaipur, M.Sc Nursing Entrance Exam-2016

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2016

Applied Physiology

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2016

Explanation

Potassium (K+) is the most abundant cation within the cells, making it the principal electrolyte of the intracellular fluid (ICF).
The intracellular concentration of potassium is approximately 140–150 mEq/L, which is vastly higher than its extracellular concentration of 3.5–5.0 mEq/L.
This high intracellular potassium level is crucial for maintaining the cell's resting membrane potential, which is essential for nerve impulse conduction and muscle contraction.
The sodium-potassium pump, an active transport system, continuously moves potassium into the cells to maintain this high concentration gradient.

Option A: Calcium (Ca2+) is primarily an extracellular cation. While it has a very low concentration inside cells, its main roles are in bone structure, blood coagulation, and muscle contraction, regulated by ECF levels.
Option B: Sodium (Na+) is the principal electrolyte of the extracellular fluid (ECF), not the intracellular fluid. It is the main driver of fluid balance and osmotic pressure in the ECF.
Option D: Magnesium (Mg2+) is an intracellular cation, but it is the second most abundant after potassium. It is not considered the principal electrolyte.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Distribution of major electrolytes in body fluid compartments as background academic context rather than a clinical decision trigger.
Monitoring serum potassium levels is a critical nursing responsibility. Because the normal extracellular (serum) range is very narrow (3.5-5.0 mEq/L), even minor deviations can lead to life-threatening cardiac dysrhythmias.
Nurses must be vigilant for signs of hypokalemia (muscle weakness, fatigue, arrhythmias) and hyperkalemia (muscle weakness, paralysis, cardiac arrest) and report them immediately.
Many common medications, especially diuretics (like furosemide) and ACE inhibitors, can significantly alter potassium levels, requiring careful patient monitoring and education.

How to Approach the Question

This is a factual recall question testing fundamental physiology.
First, identify the key terms in the question: 'principal electrolyte' and 'intracellular fluid'.
'Intracellular' means inside the cell.
Recall the basic distribution of major electrolytes. A common mnemonic is that 'salt' (Sodium) is primarily found outside the cell, in the 'sea' of extracellular fluid.
Conversely, Potassium (K+) is the main electrolyte found inside the cell.
Evaluate the options based on this core concept. Sodium is the principal ECF electrolyte, while Potassium is the principal ICF electrolyte.

Concept Tested & Keywords

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