Diuresis, or the elimination of water, salt and other solutes as well as several metabolites in the form of urine by the kidneys, is the main process of blood or arterial pressure control. This long-term regulation process acts in two ways: 1), when the levels of extracellular fluid rises, and consequently the arterial pressure and blood volume increases, the kidney is stimulated to eliminate water and salt, thus returning the blood pressure to its normal levels; and 2), when the arterial pressure is bellow normal levels, diuresis is decreased, allowing the accumulation of extracellular fluid and blood volume in order to reach the normal pressure levels.

Regulation of body fluid volume involves the alternate excretion and reabsorption by the renal tubules of different concentrations of solutes and water in the urine, such as potassium and sodium and other electrolytes. Five different hormones control specific...