Roles of Electrolytes: Sodium and Potassium

Sodium is the primary cation of extracellular fluid, making up to 90% of extracellular cations. Its concentration in blood plasma ranges from 135 - 145 mEq/L.

It is critical in maintaining fluid and electrolyte balance and the osmolarity of the extracellular fluid.

The propagation of action potentials in neurons and muscles heavily relies on the flow of sodium ions.

Sodium imbalances — hyponatremia and hypernatremia — can cause severe muscular and neuronal dysfunction.

Potassium ions are the main cations in the intracellular fluid, with a concentration of 140 mEq/L.

It plays an essential role in the conduction of nerve impulses, helps maintain the standard volume of intracellular fluid, and assists in regulating body fluid pH.

The normal potassium concentration in blood plasma is around 3.5 to 5.0 mEq/L.

Abnormal potassium levels, such as in hyperkalemia, typically caused by renal failure or aldosterone deficiency, can lead to muscular weakness and, in extreme cases, induces ventricular fibrillation.