Overview Bile necessary for digestion and absorption of lipids in gastrointestinal system synthesized and secreted by liver, stored in gallbladder Bile composition bile salts synthesis cholesterol → primary bile acids → secondary bile acids → bile salts conjugation liver conjugates bile acids with amino acids (glycine, taurine) to form bile salts conjugation changes pKs of bile acids, increasing water solubility function emulsification of dietary lipids formation of micelles with products of lipid digestion bile pigments e.g., bilirubin cholesterol phospholipids electrolytes (aka ions) water Bile Secretion Secretory pathway cholecystokinin (CCK) stimulates (1) contraction of gallbladder and (2) relaxation of sphincter of Oddi bile flows gallbladder → duodenum bile emulsifies and solubilizes dietary lipids in small intestine