Final answer:
The most prevalent cation inside cells is potassium (K+), which is about 30 times higher in concentration inside cells than in the extracellular fluid. This is maintained by sodium-potassium pumps using ATP energy.
Step-by-step explanation:
The cation that is most prevalent inside cells is potassium (K+). Potassium is a major intracellular cation and is vital for various cellular functions, including establishing the resting membrane potential in neurons and muscle fibers. The normal concentration of potassium is about 30 times higher inside the cells when compared to the extracellular fluid (ECF). This high concentration inside cells is maintained by the action of sodium-potassium pumps, which actively transport potassium ions into the cell while expelling sodium ions out. Despite the leakage through membrane pores, the cellular machinery keeps the potassium levels high inside and low outside the cell utilizing energy provided by ATP, thus maintaining essential cellular functions and overall homeostasis.
In contrast, sodium (Na+) is the principal ion in the fluid outside of cells, with concentrations about 10 times higher outside than inside the cell. These differences in ion concentrations across cell membranes are essential for various physiological processes including muscle contraction and nerve impulse transmission.