Which of the following is the major extracellular cation?

Sodium is recognized as the major extracellular cation in the body, playing a crucial role in various physiological processes. It is predominantly found in the blood and the fluid surrounding cells, contributing significantly to the regulation of blood pressure, blood volume, and overall fluid balance. Sodium is essential for maintaining the osmotic balance of extracellular fluid and is vital in the conduction of nerve impulses and muscle contraction.

In contrast, while potassium is also an important cation, it is primarily located within cells, making it the major intracellular cation rather than extracellular. Magnesium, while important for numerous enzymatic processes and also found in extracellular fluid, is present in much lower concentrations compared to sodium. Chloride, on the other hand, is primarily an anion, balancing the positive charges of cations like sodium but does not fit the criteria of being a cation itself. This distinction of sodium as the major extracellular cation is fundamental to understanding electrolyte balance and its implications for health and disease.