| Electrolyte | Physiologic Role |
|---|---|
| Sodium | Osmolarity |
| Extracellular fluid volume | |
| Action potential | |
| Potassium | Transmembrane potential |
| Action potential | |
| Calcium | Excitation–contraction |
| Neurotransmission | |
| Enzyme function | |
| Cardiac pacemaker activity | |
| Cardiac action potential | |
| Bone structure | |
| Phosphorus | Stores energy (adenosine triphosphate) |
| Component of second messengers (cyclic adenosine monophosphate) | |
| Component of cell membranes (phospholipids) | |
| Magnesium | Enzyme cofactor (sodium-potassium pump) |
| Controls potassium movement into cells | |
| Membrane excitability | |
| Bone structure |