What is the major extracellular cation in the human body?

Sodium is recognized as the major extracellular cation in the human body. It plays a crucial role in maintaining osmotic balance and fluid distribution between different body compartments. Sodium ions are essential in generating action potentials in neurons, which allows for proper nerve signaling. They also influence blood pressure regulation through their effect on blood volume.

In contrast, potassium is the primary intracellular cation and is vital for cellular functions, while calcium, although important for processes such as muscle contraction and neurotransmitter release, is present in lower concentrations in the extracellular fluid compared to sodium. Chloride primarily functions as an anion in the extracellular fluid, helping to maintain electrical neutrality and balance. Therefore, sodium’s predominant role in extracellular space makes it the correct answer to the question about the major extracellular cation.