by Tarek Musslimani

Created on: August 17, 2010   Last Updated: August 18, 2010

Electrolytes in the body are special ions and cations that each have a specific role in the body.  These electrolytes are physiologically essential for the normal function of the body tissues.  Electrolytes are soluble in water due to the presence of the charge on them.  They are distributed in the body between the extracellular and intracellular spaces.  This distribution is based on active transport of these ions across the cellular membrane that uses enzymes for this purpose. 

Certain electrolytes such as sodium ions control osmosis of water between the body compartments.  For example, excess sodium in the body can cause an osmotic effect on water increasing its re-absorption in the kidney tubules. Also when administering diuretics that decrease the re-absorption of sodium in the kidney tubules, the increased amount of sodium ions in the renal tubules exert an osmotic effect on water causing its diuresis in the urine. 

This osmotic effect of ions on water is not restricted to ions but also is observed with molecules which can also exert osmotic effect such as glucose and mannitol.  For example, in diabetes mellitus in which there is a state of hyperglycemia there is increased filtration of glucose in the glomeruli of the kidney.  The filtered glucose exerts an osmotic effect on water leading to its diuresis in the urine. 

Other functions of ions in the body act as buffers.  Especially notable here are the ions, phosphates and bicarbonates in addition to hydrogen ions.  Bicarbonate is the major buffer in the blood and the extracellular space.  While phosphate ions are the major buffers inside the cell.  In addition to phosphates also intracellular proteins usually function as buffers such as the hemoglobin molecules.  Other buffers in the body include the ammonia molecule which is the degradation product of amino acids.  It is obtained from the deamination process of certain amino acids. Protons or hydrogen ions are also present in the body.  They are also a type of electrolyte which can function as a buffer for bases. 

Acids are usually obtained in the body as a result of metabolic reactions such as anaerobic respiration in the case of ischemia which leads to the accumulation of lactic acids.  Also in diabetes mellitus the accumulation of ketonic acids in diabetic ketoacidosis can lead to the accumulation of acids in the body.  These

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