Acid-base imbalance

Overview
Acid-base imbalance has several possible causes. An excess of acid is called acidosis and an excess in bases is called alkalosis. Acidosis is much more common than alkalosis. The imbalance is compensated by negative feedback to restore normal values. There are various renal responses to acidosis and alkalosis.

Causes
Sources of acid gain:
 * 1) Carbon dioxide (since CO2 and H2O form HCO3-, bicarbonate, and H+, a proton, in the presence of carbonic anhydrase)
 * 2) Production of nonvolatile acids from the metabolism of proteins and other organic molecules
 * 3) Loss of bicarbonate in faeces or urine
 * 4) Intake of acids or acid precursors

Sources of acid loss:
 * 1) Use of hydrogen ions in the metabolism of various organic anions
 * 2) Loss of acid in the vomitus or urine

Response
Responses to acidosis:
 * 1) Bicarbonate is added to the blood plasma by tubular cells.
 * 2) * Tubular cells reabsorb more bicarbonate from the tubular fluid.
 * 3) * Collecting duct cells secrete more hydrogen and generate more bicarbonate.
 * 4) Ammoniagenesis leads to increased buffer formation (in the form of NH3)

Responses to alkalosis:
 * 1) Excretion of bicarbonate in urine.
 * 2) *This is caused by lowered rate of hydrogen ion secretion from the tubular epithelial cells.
 * 3) *This is also caused by lowered rates of glutamine metabolism and ammonia excretion.