ELECTROLYTE, in biochemistry, electrolytes are the ions in the body fluids that serve such funetions as regulating water balance, osmotic pressure, acid-base balance, and nerve and muscle irritability. The electrolytes inelude sodium, potassium, magnesium, chloride, calcium, bicarbonate, carbonic acid, sulfate, organic and inorganic phosphates, organic acids, and protein.
The electrolyte composition of blood plasma and of a typical celi fluid is shown below. Any variation of more than about 10% in the ion concentration is harmful to the body. Ion concentration is controlled by balancing dietary intake with excretion by the kidneys and, to a much lesser extent, the skin.
Sodium and potassium serve a number of funetions in the body. Sodium is important in maintaining the proper volumes of extracellular fluids. If this balance is upset, edema or dehydration occurs. Potassium is an aetivator for many enzymes. Sodium and potassium ions are involved in the propagation of nerve impulses. Both ions are excreted by the kidneys. Wide variations in the plasma sodium levels are not harmful if the osmotic pressure of the fluid is not greatly altered. However, the plasma level of potassium is critical. Either high or low concentrations affect the heart, nerves, and museles and a severe imbalance may result in death due to heart failure.
Calcium is essential for the activity of many enzymes, blood elotting, transmission of nerve impulses, and muscle contraction. Phosphate ions are constituents of many metabolic intermediates and of nucleic acids. Bone consists largely of basic calcium phosphate embedded in an organic matrix and thus serves as a reservoir of both calcium and phosphate.
Magnesium acts as an aetivator for many enzymes involved in the metabolism of fats, proteins, and carbohydrates. It also affects nerve irritability. Magnesium. deficiency causes muscle tetany, while an overabundance reduces nerve irritability and acts as an anesthetic.
The sulfate ion is important for the detoxification of certain substances.
Carbonic acid and the bicarbonate ion are parts of the buffer system of the body fluids and act to control the acid-base balance.