Key Electrolytes in the Body

Ion	Major Physiological Roles
Sodium (Na+)	Primary positive ion in extracellular fluid. Together with potassium, maintains electrolyte balance across all cell membranes. Vital to many basic physiological functions.
Potassium (K+)	Primary positive ion in intracellular fluid. Together with sodium, maintains electrolyte balance across all cell membranes. Vital to many basic physiological functions.
Magnesium (Mg2+)	Required for activity of many enzymes.
Calcium (Ca2+)	Major mineral in body and component of bone. Helps maintain normal heartbeat and nerve and muscle function.
Chloride (Cl−)	Primary negative ion in extracellular fluid. Plays a role in nerve function and other metabolic processes.
Phosphate (HPO42−)	Primary negative ion in intracellular fluid. Serves as an important buffer to maintain proper pH. Phosphorus is a major component of bone and is involved in almost all metabolic processes.