 Dear students, in this topic we shall discuss the endocrine secretions of bile and bile salts. Bile is secreted in vertebrates by the liver. It does not contain any enzymes, but it contains many important salts. These bile salts are essential for the digestion of fats. Bile is a weakly basic mixture which contains water, cholesterol, lecithin, many inorganic salts, various organic salts and bile pigments. The organic salts of bile are manufactured in the liver from cholesterol and amino acids which are complexed with sodium. These bile pigments are derived from biliverdin and bilirobin which are the products of breakdown of hemoglobin. Dear students, bile is transported from the gallbladder into the gallbladder by a hepatic duct from liver. Bile duct comes out of the liver which takes this bile to the gallbladder. Gallbladder stores this bile and concentrates it during storage. Concentration of bile in the gallbladder involves permeability of the epithelium of gallbladder. This gallbladder epithelium helps in the osmotic removal of water. In addition to this, the concentration process includes active transport of sodium and chloride ions which are taken out of the bile. Dear students, bile performs many functions which are important especially for the digestion of fats. The first function of bile is due to its alkalinity which neutralizes the acidic content of the food coming from stomach. Bile is secreted in the duodenum. The duodenum also receives acidic food from stomach. To reduce the acidity of acidic food, various salts act in the bile and help in making alkaline. The most important function of bile salts is that they work as a detergent. This detergent emulsifies fats. As a result, fats become water soluble. This action of emulsification of the bile salts facilitates later enzymatic digestion of fats. The third important function of bile salts is that it also acts on lipid soluble vitamins and disperses them and helps in absorption and transport. In addition to this, the bile uses the liver to remove certain metabolites and waste substances. The liver works as an outlet for the gallbladder in which the bile is sent and the bile has to be released from the body through the digestive tract. For example, the products of breakdown of hemoglobin pigments, cholesterol, steroids, metabolites of drugs are included in the bile. When the bile is secreted in the intestine, gastrointestinal enzymes act on these products or they are digested or these products are excreted out of the body as such.