Bile secretion is proportional to concentration of fat. The liver produces and secretes 250 to 1500mL of bile per day. The major constituents of bile are bilirubin, biliverdin, bile salts, cholesterol and phospholipids. The bile salts play a very important role in the digestion of fats. The bile salt, which are partly water and partly lipid-soluble, emulsify the fat particles and as a result the fat-drops acquired a greater surface area.