Biliary tree
Encyclopedia
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
term for the path by which bile
Bile
Bile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...
is secreted by the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
then transported to the first part of the small intestine
Small intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
, also known as the duodenum
Duodenum
The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum...
. A structure common to most members of the mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
family, it is referred to as a tree because it begins with many small branches which end in the common bile duct, sometimes referred to as the trunk of the biliary tree. The duct, the branches of the hepatic artery
Common hepatic artery
In anatomy, the common hepatic artery is a short blood vessel that supplies oxygenated blood to the liver, pylorus , duodenum and pancreas....
and the portal vein
Hepatic portal vein
The hepatic portal vein is not a true vein, because it does not conduct blood directly to the heart. It is a vessel in the abdominal cavity that drains blood from the gastrointestinal tract and spleen to capillary beds in the liver...
form the central axis of the portal triad
Portal triad
A portal triad is a distinctive arrangement in the liver. It is a component of the hepatic lobule. It consists of the following five structures:* hepatic artery* hepatic portal vein* bile duct*lymphatic vessels...
. Bile flows in the direction opposite to that of the blood present in the other two channels.
The name usually excludes the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
, but sometimes does include it.
Clinical significance
Pressure inside in the biliary tree can give rise to gallstoneGallstone
A gallstone is a crystalline concretion formed within the gallbladder by accretion of bile components. These calculi are formed in the gallbladder, but may pass distally into other parts of the biliary tract such as the cystic duct, common bile duct, pancreatic duct, or the ampulla of...
s and lead to cirrhosis of the liver.
Blockage can cause jaundice
Jaundice
Jaundice is a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae , and other mucous membranes caused by hyperbilirubinemia . This hyperbilirubinemia subsequently causes increased levels of bilirubin in the extracellular fluid...
.
The biliary tract can also serve as a reservoir for intestinal tract infections. Since the biliary tract is an internal organ, it has no somatic nerve supply
Somatic nervous system
The somatic nervous system is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles...
, and colicky pain due to infection and inflammation of the biliary tract is not a somatic pain. Rather, pain may be caused by luminal distension, which causes stretching of the wall. This is the same mechanism that causes pain in bowel obstruction
Bowel obstruction
Bowel obstruction is a mechanical or functional obstruction of the intestines, preventing the normal transit of the products of digestion. It can occur at any level distal to the duodenum of the small intestine and is a medical emergency...
s.
Path
The path is as follows:- Bile canaliculi >> Canals of HeringCanals of HeringThe Canals of Hering, or intrahepatic bile ductules, are part of the outflow system of exocrine bile product from the liver.-Anatomy:They are found between the bile canaliculi and interlobular bile ducts near the outer edge of a classic liver lobule...
>> bile ductules (in portal tracts) >> intrahepatic bile ducts >> left and right hepatic ducts >> - merge to form >> common hepatic ductCommon hepatic ductThe common hepatic duct is the duct formed by the convergence of the right hepatic duct and the left hepatic duct . The common hepatic duct then joins the cystic duct coming from the gallbladder to form the common bile duct...
>> - exits liver and joins >> cystic ductCystic ductThe cystic duct is the short duct that joins the gall bladder to the common bile duct. It usually lies next to the cystic artery. It is of variable length...
(from gall bladder) >> - forming >> common bile ductCommon bile ductThe common bile duct is a tube-like anatomic structure in the human gastrointestinal tract. It is formed by the union of the common hepatic duct and the cystic duct . It is later joined by the pancreatic duct to form the ampulla of Vater...
>> joins with >> pancreatic ductPancreatic ductThe pancreatic duct, or duct of Wirsung , is a duct joining the pancreas to the common bile duct to supply pancreatic juices which aid in digestion provided by the "exocrine pancreas"...
>> - forming >> ampulla of Vater >> enters duodenum