Water is the main component of the body. In fact, an average 1000 pound horse is roughly 660 pounds (80 gallons) of water. About two-thirds of this water is inside cells, called intracellular fluid, and one-third is outside cells or extracellular fluid. To function normally, the body must keep the amount of water in these areas in balance and relatively constant. This is termed water balance. The water in the body contains dissolved mineral salts called electrolytes, primarily sodium, chloride, potassium, calcium and magnesium. These dissolved electrolytes exist as ions, which are charged particles that conduct electric currents, thus the name electrolytes. Electrolytes are used to maintain voltages across cell membranes, and are distributed through the body in a highly ordered way. Any disruption of this order can result in severe body dysfunction, including heart and gastrointestinal problems, muscle cramps and impaired brain and nerve function. Sodium and chloride concentrations are normally higher in extracellular fluid, while potassium concentration is higher in intracellular fluid. Electrolyte balance is tied very closely with water balance.