Structure and function of the gallbladder and biliary tract

Biliary tract They consist of internally- and extrahepatic bile ducts. Bile, produced by hepatocytes, is released in the bile capillaries. She then enters the intrahepatic bile ducts.

Because the liver excreted through the bile the right and left hepatic ducts, which form the common hepatic duct. Because of the common hepatic duct bile is mainly supplied through the cystic duct into the gallbladder.

A small amount of bile may enter the common hepatic duct directly into the common bile duct, bypassing the gallbladder.

The common bile duct It starts from the confluence of the common hepatic duct and cystic. Because of the common bile duct bile is released into the duodenum. The gallbladder concentrates the bile and takes a dark olive-yellow color, capacity of 40-60 ml of the gallbladder.

The mucous membrane of the biliary tract covered with prismatic (cylindrical) epithelium, cells whose small size. The gall bladder is also lined with high prismatic epithelium, whose cells have microvilli with striated rim. Especially small prismatic epithelial cells lining the hepatic ducts. Duodenal mucosa is lined with high columnar epithelium (height about 30 m), cells which have the cuticle and lint.

The function of the biliary tract It carried out under the influence of neurohumoral regulation. During digestion and amplification duodenal motility or after duodenal administration via stimulus probe (Magnesium sulfate, sorʙita, olive oil, egg yolk, etc.. d.) in the mucosa of the duodenum produced biologically active ingredient - cholecystokinin (pankreozimin), which causes relaxation of the sphincter of the common hepatic duct and gallbladder contraction. Bile is released into the duodenum, which is involved in digestion. Under the influence of bile into the duodenum emulsified fats, which are further subjected to the action of pancreatic lipase. Fats and fat-soluble vitamins are absorbed in the presence of bile in the duodenum.

The assimilation of phylloquinone (Vitamin K), needed for synthesis in the liver prothrombin, проконвертина и IX, X, XI plasma clotting factors, are important bile acids. Besides, bile, getting into the duodenum, It stimulates the secretion of digestive juices of the pancreas, stomach and intestines.

In turn, duodenum reflex and humoral way has a significant influence on the tone of the biliary tract.

For Example, increasing the pressure in the lumen of the duodenum is accompanied by hypertension, hepatic, pancreatic sphincter ampoule (sfinktera simple), and the reduction contributes to its disclosure.

Hormones, produced by the duodenal mucosa (secretin, cholecystokinin-pancreozymin, and others.), actively influence the tone of the sphincter of pancreatic and hepatic ampoules and contraction of the gallbladder.