The liver continuously produces bile. If there is no secretion of bile into the intestine (with digestion), the bile is stored in the gall bladder. A five to ten fold concentration of bile salts, bilirubine and cholesterol take place, due to the strong resorption of water and electrolytes. Bile that comes directly from the liver therefore has a different composition (especially less acid) then bile that has been stored in the gallbladder, the PH of the latter can drop to 5.6. Because the bile that is stored in the gallbladder is so concentrated, gall stones easily develop. The gall stones consist of cholesterol, bilirubine and calcium salts, in varying concentrations. The development of stones is promoted by a prolonged storage of bile in the gallbladder and by inflammation of the gallbladder (cholecystitis).