Bile is a complex biological fluid. In a lot of bile components. The basic amount of its mass bile acids, cholesterol, phospholipids and bile pigments.
Bile acids are formed in the liver from cholesterol. In the synthesis of bile acids, mainly cholic acid and dezoksiholevaya, spent from 40 to 45% of the total stock of cholesterol in the body. Once in the intestine, bile acids are involved in the process of digestion and absorption of fats.
Thanks to bile acids, cholesterol dissolved in bile, which is not soluble in water. Bile acids themselves stimulate the excretion of bile from the liver. In the intestine, bile acids activate the motor activity of the muscles of small and large intestine, transport of water and electrolytes through the intestinal wall into the bloodstream.
In about 5 per day is produced, the bile acids that are far from sufficient for the needs of the body. Therefore, bile acids are absorbed from the intestine back into the blood. Through the portal vein, they fall into the liver, then in the space of Disse (the space between the capillaries and liver cells) and captured microvilli of liver cells. Liver cells secrete bile acids back into the bile.
Part of bile acids from the small intestine enters the fat and excreted from the body. With the strong entry of bile acids in the body with drugs or foods, the synthesis of bile acids in the liver is slowed down and enhanced by loss of bile acids (deleting part of the small intestine, taking cholestyramine), their synthesis is enhanced.
Bile is secreted by liver cells (hepatocytes), comes from the cells of the liver into the bile ducts, which are located in the hepatic lobules. Bile ducts coalesce to form larger ducts, which empty into the interlobular ducts. Interlobular ducts merge into a septal ducts.
The bottom surface of the liver bile duct are two main, left and right, merge and form a common hepatic duct. Common hepatic duct is connected to the duct from the gallbladder and common bile duct is called the (common bile duct). The length of the common bile duct of about 10 cm It passes through the head of the pancreas and empties into the duodenum.
Place the confluence of the bile duct into the duodenum is called duodenal papilla large. In the wall of the duct in the gut is the confluence of the circular muscle layer, which forms the sphincter. This is called the sphincter of Oddi sphincter.
Thus, the extrahepatic biliary tract consists of the gallbladder, right, left and common hepatic duct, cystic duct and common bile duct.
The liver secretes bile under a pressure of about 300 mm of water column. The pressure in the gall bladder, if before mealtime, he fell and was released from the bile, is 100 mm water column. Bile from the liver enters the gallbladder is freed up until the pressure in the gall bladder is not equal to the pressure in the hepatic bile ducts. All this happens under the condition that the stomach is empty, the digestive process is absent and the sphincter of Oddi is closed. In the gall bladder contains about 50 ml of bile.
The musculature of the gall bladder is in a constant tone, slowly stirring the bile. At the time of the meal duodenal mucosa synthesizes the hormone cholecystokinin. This hormone stimulates the reduction of the gall bladder, sphincter of Oddi relaxes, stimulates contraction of the muscles of bile ducts. As a result of the duodenum through the papilla major duodenal bile comes from the common bile duct. Of the hepatic bile duct enters synthesized in the liver and released from the gall bladder bile is more concentrated.