Acid-base buffering system

The acid-base buffering system is a vital physiological framework responsible for maintaining the body's arterial blood pH within the narrow range of 7.35 to 7.45, which is critical for optimal enzymatic activity and cellular function (StatPearls, NBK507807). It operates through three integrated mechanisms: chemical buffers in the blood (primarily the bicarbonate, phosphate, and protein systems), respiratory compensation via the lungs, and metabolic compensation via the kidneys (StatPearls, NBK507807; Merck Manual). The bicarbonate buffer system is the most prominent extracellular buffer, utilizing the reversible reaction of CO2 and water to form carbonic acid, which dissociates into bicarbonate and hydrogen ions, a process often facilitated by the enzyme carbonic anhydrase (StatPearls, NBK557736). Clinical disturbances in this system result in acidosis or alkalosis, which can stem from respiratory failure, renal dysfunction, or metabolic insults like ketoacidosis (StatPearls, NBK448098). Therapeutic management involves addressing the underlying cause and may include the administration of buffering agents like sodium bicarbonate or the use of drugs like acetazolamide to manipulate renal ion handling (StatPearls, NBK557736; Merck Manual).

Other names

pH buffering systemAcid-base homeostasisBicarbonate buffer systemPhosphate buffer systemProtein buffer system

The system functions through the chemical neutralization of excess hydrogen or hydroxide ions by buffer pairs, the respiratory regulation of carbon dioxide partial pressure through ventilation, and the renal regulation of bicarbonate reabsorption and hydrogen ion excretion (StatPearls, NBK507807).