Acid-base balance and ph homeostasis, are crucial factors for normal body functioning, cell metabolism, and function.The body’s Metabolic processes, continuously produce acids. Hydrogen ions (H+ )are reactive as they can attach to negatively charged proteins and, therefore modify a protein’s configuration, function, and charge. Consequently, outside of an acceptable pH range, a variety of physiologic dysfunctions arise,  for example, denaturation of proteins such as enzymes and plasma proteins, change of membranes permeability and electrolyte distribution.  Daily, the plasma ph is influenced by external and internal factors on a regular basis. Small quantities of acidic substances enter the body with the ingested foods, however, the largest part of hydrogen ions originate as by-products of cellular respiration and conduce to disturbance of plasma ph balance.The greatest amount of acid comes from Carbohydrate and fat metabolism. According to the data in the article by James L. Lewis, Metabolism of carbohydrates and fats generates 15,000 to 20,000 mmol of carbon dioxide daily. Despite carbonic dioxide is not an acid, in the presence of a member of the carbonic anhydrase family of enzymes, it combines with water in the blood. As a consequence carbonic acid is formed: CO2+H20= H2CO3. This easily dissociates into hydrogen ion (H+) and bicarbonate (HCO3?).Lesser quantities of organic acid originate from  : 1. Lactic acid and ketoacids, resulting from the incomplete metabolism of glucose(C6H12O6) and fatty acids.2. Sulfuric acid, resulting from the metabolism of cysteine and methionine (sulfur-containing amino acids)3.  Metabolism of arginine, lysine, and histidine (cationic amino acids)Most bases come from :1.Metabolism of glutamate and aspartate (anionic amino acids) as they consume acid when oxidized and thus decrease the acid load.2 .Oxidation and consumption of organic anions (lactate and citrate) which produce bicarbonate.he kidneys have the predominant role in regulating the To maintain proper cellular function, the body has elaborate mechanisms that maintain blood Hydrogen ions (H+) concentration within a very narrow physiological range. It is typically 37 to 43 nmol/L. Therefore, the physiologic range of the pH is 7.43 to 7.37, where pH =?log H+. To maintain ph within this limits, the body uses three different mechanisms: The first is a chemical buffer, the second line of defense is the respiratory system, and last and the predominant one, is the renal system,  that will be discussed below.