What is the major cation found in intracellular fluid?

The major cation found in intracellular fluid is potassium. This is crucial because potassium plays a vital role in various cellular functions, including maintaining resting membrane potential, facilitating muscle contractions, and regulating enzyme activity. Intracellular fluid, which constitutes the fluid within cells, has a high concentration of potassium relative to other cations, which is essential for processes like nerve impulse transmission and cellular metabolism.

In contrast, sodium, while abundant in extracellular fluid, is maintained at lower levels within cells due to the activity of the sodium-potassium pump, which helps regulate the distribution of these ions across cell membranes. Calcium and magnesium also play important roles in cellular processes, but their concentrations do not match that of potassium in intracellular fluid. Understanding this concentration gradient and the role of potassium helps to appreciate how cells maintain their function and respond to physiological demands.