The bile ducts connect the gallbladder (vesica fellea or biliaris, Latin vesica “bladder” and fellis or bilis “bile”) to the small intestine. Through the bile ducts, bile synthesized (formed) in the liver and concentrated (thickened to about 10% of its initial volume; 30-80 ml of bile) in the gallbladder is directed to the small intestine, where it serves mainly for fat digestion and absorption.In the bile duct system, mechanical and chemical defense systems ensure that bacteria cannot colonize and cause infections. For example, the sphincter Oddi (sphincter in the area where the bile duct opens into the duodenum/duodenum) closes the ductus choledochus (common bile duct) against the intestinal lumen. The permanent flow of bile prevents the ascending (“ascending”) of germs from the duodenum (duodenum). The bile itself is sterile. The bile itself or its components (bile acids/bile salts) have an antibiotic effect.As long as the bile can flow freely, pathogenic (pathological) bacterial colonization of the bile ducts does not occur.