The main intracellular cation is?

Appeared in: AIIMS Patna NO - 2020

Explanation

Potassium (K⁺) is the most abundant cation within the cell (intracellular fluid).
The normal intracellular concentration of potassium is approximately 140–150 mEq/L, whereas the extracellular concentration is only 3.5–5.0 mEq/L.
This high intracellular concentration is maintained by the sodium-potassium pump.
Potassium is essential for critical physiological functions, including nerve impulse transmission, muscle contraction, and maintaining the heart's rhythm.

Option A: Zinc is a trace element, not a major cation responsible for establishing the primary electrical charge or fluid balance within cells.
Option B: Chloride (Cl⁻) is an anion (negatively charged ion), not a cation. Furthermore, it is the most abundant anion in the extracellular fluid, not intracellular.
Option D: Halide is a chemical category for ions of halogen elements (e.g., chloride, fluoride, bromide). It is not a specific electrolyte found in the body in the same way as potassium or sodium.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Major intracellular and extracellular electrolytes as background academic context rather than a clinical decision trigger.
Monitoring serum potassium levels is a critical nursing responsibility, as both low levels (hypokalemia) and high levels (hyperkalemia) can cause life-threatening cardiac dysrhythmias.
Nurses must be cautious when administering IV potassium, as rapid infusion can cause cardiac arrest. It must be diluted and infused slowly.
Many medications, such as diuretics, ACE inhibitors, and digoxin, can affect potassium levels, requiring careful patient monitoring and education.

How to Approach the Question

First, break down the question to its core components: 'main', 'intracellular' (inside the cell), and 'cation' (positively charged ion).
Recall the distribution of major electrolytes in the body's fluid compartments.
Evaluate each option against the criteria. Zinc is a trace element. Chloride is an anion and is extracellular. Halide is a chemical group.
Identify Potassium (K⁺) as the primary cation found in high concentrations inside the cell.
Confirm the answer by remembering the function of the Sodium-Potassium pump, which actively pumps K⁺ into cells and Na⁺ out of cells.

Concept Tested & Keywords

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Practise the full AIIMS Patna NO - 2020

Attempt every question from this paper in a timed mock, then review the full solution for each one.