Final answer:
c) Sodium Sodium is the chief ion used to maintain the volume of fluid outside cells due to its high concentration in the extracellular fluid.
Step-by-step explanation:
The chief ion used to maintain the volume of fluid outside cells is sodium. In body fluids, sodium ions are primarily responsible for regulating the extracellular fluid (ECF) volume because of their high concentration in that compartment. Normal sodium concentrations are about 10 times higher in the ECF compared to the intracellular fluid (ICF). The sodium-potassium pump, which uses ATP to exchange sodium and potassium ions across the cell membrane, plays a critical role in maintaining the different concentrations of these ions inside and outside the cells.
While sodium is the major extracellular cation, potassium is the primary intracellular cation, and its concentration is maintained at about 30 times higher inside than outside of cells.The chief ion used to maintain the volume of fluid outside cells is sodium (Na+). Sodium ions are concentrated in the extracellular fluid (ECF) of the body. They are maintained at high levels outside the cells by sodium-potassium pumps in the cell membranes, which use ATP energy to pump sodium out of the cell.