Electrolytes help regulate water distribution, govern acid-base balance, and transmit nerve impulses. They also contribute to energy generation and blood clotting. This table summarizes the functions of each of the body's major electrolytes. Check the illustration below to see how electrolytes are distributed in and around the cell.
Potassium (K)
- Main ICF cation
- Regulates cell excitability
- Permeates cell membranes, thereby affecting the cell's electrical status
- Helps to control ICF osmolality and, consequently, ICF osmotic pressure
Magnesium (Mg)
- A leading ICF cation
- Contributes to many enzymatic and metabolic processes, particularly protein synthesis
- Modifies nerve impulse transmission and skeletal muscle response (unbalanced Mg concentrations dramatically affect neuromuscular processes)
- Maintains cell membrane stability
Phosphorus (P)
- Main ICF anion
- Promotes energy storage and carbohydrate, protein, and fat metabolism
- Acts as a hydrogen buffer
Sodium (Na)
- Main ECF cation
- Helps govern normal ECF osmolality (a shift in Na concentrations triggers a fluid volume change to restore normal solute and water ratios)
- Helps maintain acid-base balance
- Activates nerve and muscle cells
- Influences water distribution (with chloride)
Chloride (Cl)
- Main ECF anion
- Helps maintain normal ECF osmolality
- Affects body pH
- Plays a vital role in maintaining acid-base balance; combines with hydrogen ions to produce hydrochloric acid
Calcium (Ca)
- A major cation in teeth and bones; found in fairly equal concentrations in ICF and ECF
- Also found in cell membranes, where it helps cells adhere to one another and maintain their shape
- Acts as an enzyme activator within cells (muscles must have Ca to contract)
- Aids coagulation
- Affects cell membrane permeability and firing level
Bicarbonate (HCO32)
- Present in ECF
- Regulates acid-base balance
