Pathophysiology of Acid Base Regulation
The need for the existence of multiple mechanisms involved in acid-base regulation stems from the critical importance of the hydrogen ion (H+) concentration on the operation of many cellular enzymes and function of vital organs, most prominently the brain and the heart . The task imposed on the mechanisms that maintain acid-base homeostasis is large since metabolic pathways are continuously consuming or producing H+, and the daily load of waste products for excretion in the form of volatile (carbonic acid) and fixed acids is substantial. The equilibrium reaction of water and CO2, the end product of oxidative metabolism, results in the daily formation of large amounts of carbonic acid, approximately 15,000 mEq/day . The acceptance of the H+ derived from carbonic acid by haemoglobin results in the transformation of carbonic acid into bicarbonate, and this ion transports ∼ 80% of the CO2 added to the blood from the peripheral tissues to the lungs. As red cells reach the lungs and oxygen is taken up by haemoglobin, H+ is released decomposing bicarbonate into CO2 that diffuses into the alveoli for final excretion. The presence of carbonic anhydrase in red cells facilitates bicarbonate generation in peripheral tissues and decomposition in the lungs, speeding up the mechanisms of blood CO2 loading and unloading.
KeywordsMetabolic Acidosis Lactic Acidosis Metabolic Alkalosis Urea Synthesis Fixed Acid
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- 1.Adrogué HJ, Wesson DE (1994) Acid-base. Blackwell’s basics of medicine. Blackwell Science, BostonGoogle Scholar
- 2.Cohen JJ, Kassirer JP (1982) Acid/base. Little, Brown, BostonGoogle Scholar
- 3.Cohen RD (1995) The liver and acid-base regulation. In: Arieff AI, DeFronzo RA (eds) Fluid, electrolyte, and acid-base disorders. Churchill Livingstone, New York, pp 777–790Google Scholar
- 6.Hood VL, Tannen RL (1994) Maintenance of acid base homeostasis during ketoacidosis and lactic acidosis: Implications for therapy. Diabetes/Metab Rev 2:177–194Google Scholar
- 7.Madias NE (1995) Fluid, electrolyte and acid-base disorders. In: Jacobson HR, Striker GE, Klahr S (eds) The principles and practice of nephrology. Decker, Philadelphia, pp 864–963Google Scholar
- 9.Alberti KGMM (1990) Diabetic acidosis, hyperosmolar coma, and lactic acidosis. In: Becker KL (ed) Principles and practice of endocrinology and metabolism. Lippincott, Philadelphia, pp 1175–1187Google Scholar