Bile duct
Encyclopedia
A bile duct is any of a number of long tube-like structures that carry bile
.
Bile, required for the digestion
of food, is excreted by the liver
into passages that carry bile toward the hepatic duct, which joins with the cystic duct
(carrying bile to and from the gallbladder
) to form the common bile duct
, which opens into the intestine
.
The biliary tree (see below) is the whole network of various sized ducts branching through the liver.
The path is as follows: Bile canaliculi → Canals of Hering
→ interlobular bile ducts
→ intrahepatic bile ducts
→ left and right hepatic ducts merge to form → common hepatic duct
exits liver and joins → cystic duct
(from gall bladder) forming → common bile duct
→ joins with pancreatic duct
→ forming ampulla of Vater → enters duodenum
, gallstones, or scarring from injury prevents the bile from being transported to the intestine and the active ingredient in the bile (bilirubin
) instead accumulates in the blood
. This condition results in jaundice
, where the skin
and eyes become yellow from the bilirubin in the blood. This condition also causes severe itchiness from the bilirubin deposited in the tissues. In certain types of jaundice, the urine will be noticeably darker, and the stools will be much paler than usual. This is caused by the bilirubin all going to the bloodstream and being filtered into the urine by the kidneys, instead of some being lost in the stools through the ampulla of Vater.
Jaundice
is commonly caused by conditions such as pancreatic cancer
, which causes blockage of the bile duct passing through the cancerous portion of the pancreas; cholangiocarcinoma
, cancer of the bile ducts; blockage by a stone in patients with gallstone
s; and from scarring after injury to the bile duct during gallbladder removal.
, activation of the brain stem
and the insular cortex
, prefrontal cortex
, and somatosensory cortex.
or biliary catheter). It can be used to relieve a blockage in the bile duct, either permanently or as a temporary solution before definite treatment such as surgery. The drain can be placed percutaneous
ly through the liver, with the procedure then being called percutaneous transhepatic biliary drainage (PTBD). This can additionally be performed as part of a percutaneous transhepatic cholangiography
, then a form of interventional radiology
. A biliary drain can also be used to take bile samples for diagnostic workup or disease monitoring, as well as providing a route of administration
for medical substances.
In infants with biliary atresia
, hepatoportoenterostomy
is an alternative method of providing bile drainage.
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...
.
Bile, required for the digestion
Digestion
Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones....
of food, is excreted 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...
into passages that carry bile toward the hepatic duct, which joins with the cystic duct
Cystic duct
The 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...
(carrying bile to and from the gallbladder
Gallbladder
In vertebrates the gallbladder is a small organ that aids mainly in fat digestion and concentrates bile produced by the liver. In humans the loss of the gallbladder is usually easily tolerated....
) to form the common bile duct
Common bile duct
The 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...
, which opens into the intestine
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
.
The biliary tree (see below) is the whole network of various sized ducts branching through the liver.
The path is as follows: Bile canaliculi → Canals of Hering
Canals of Hering
The 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...
→ interlobular bile ducts
Interlobular bile ducts
The interlobular bile ducts carries bile in the liver between the Canals of Hering and the intrahepatic bile ducts. They are part of the interlobular portal triad and can be easily localized by looking for the much larger portal vein. The cells of the ducts are described as cuboidal epithelium...
→ intrahepatic bile ducts
Intrahepatic bile ducts
Intrahepatic bile ducts are part of the outflow system of exocrine bile product from the liver.They can be divided into large and small ducts. Examples include:* Large: left and right hepatic ducts* Small: interlobular bile ducts...
→ left and right hepatic ducts merge to form → common hepatic duct
Common hepatic duct
The 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 duct
Cystic duct
The 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 duct
Common bile duct
The 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 duct
Pancreatic duct
The 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
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...
Pathology
Blockage of the bile duct by a cancerCancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
, gallstones, or scarring from injury prevents the bile from being transported to the intestine and the active ingredient in the bile (bilirubin
Bilirubin
Bilirubin is the yellow breakdown product of normal heme catabolism. Heme is found in hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases...
) instead accumulates in the blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
. This condition results in 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...
, where the skin
Human skin
The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals,...
and eyes become yellow from the bilirubin in the blood. This condition also causes severe itchiness from the bilirubin deposited in the tissues. In certain types of jaundice, the urine will be noticeably darker, and the stools will be much paler than usual. This is caused by the bilirubin all going to the bloodstream and being filtered into the urine by the kidneys, instead of some being lost in the stools through the ampulla of Vater.
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...
is commonly caused by conditions such as pancreatic cancer
Pancreatic cancer
Pancreatic cancer refers to a malignant neoplasm of the pancreas. The most common type of pancreatic cancer, accounting for 95% of these tumors is adenocarcinoma, which arises within the exocrine component of the pancreas. A minority arises from the islet cells and is classified as a...
, which causes blockage of the bile duct passing through the cancerous portion of the pancreas; cholangiocarcinoma
Cholangiocarcinoma
Cholangiocarcinoma is a cancer of the bile ducts which drain bile from the liver into the small intestine. Other biliary tract cancers include pancreatic cancer, gallbladder cancer, and cancer of the ampulla of Vater...
, cancer of the bile ducts; blockage by a stone in patients with gallstone
Gallstone
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 from scarring after injury to the bile duct during gallbladder removal.
Sensation
Inflation of a balloon in the bile duct causes through the vagus nerveVagus nerve
The vagus nerve , also called pneumogastric nerve or cranial nerve X, is the tenth of twelve paired cranial nerves...
, activation of the brain stem
Brain stem
In vertebrate anatomy the brainstem is the posterior part of the brain, adjoining and structurally continuous with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves...
and the insular cortex
Insular cortex
In each hemisphere of the mammalian brain the insular cortex is a portion of the cerebral cortex folded deep within the lateral sulcus between the temporal lobe and the frontal lobe. The cortical area overlying it towards the lateral surface of the brain is the operculum...
, prefrontal cortex
Prefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...
, and somatosensory cortex.
Drainage
Biliary drainage is performed with a tube or catheter (called a biliary drain, biliary stentStent
In the technical vocabulary of medicine, a stent is an artificial 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow...
or biliary catheter). It can be used to relieve a blockage in the bile duct, either permanently or as a temporary solution before definite treatment such as surgery. The drain can be placed percutaneous
Percutaneous
In surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an "open" approach where inner organs or tissue are exposed .The percutaneous approach is commonly used in vascular procedures...
ly through the liver, with the procedure then being called percutaneous transhepatic biliary drainage (PTBD). This can additionally be performed as part of a percutaneous transhepatic cholangiography
Percutaneous transhepatic cholangiography
Percutaneous transhepatic cholangiography or percutaneous hepatic cholangiogram is a radiologic technique used to visualize the anatomy of the biliary tract. A contrast medium is injected into a bile duct in the liver, after which X-rays are taken...
, then a form of interventional radiology
Interventional radiology
Interventional radiology is a specialty of radiology, in which image-guided procedures are used to diagnose and treat a multitude of diseases across all body systems...
. A biliary drain can also be used to take bile samples for diagnostic workup or disease monitoring, as well as providing a route of administration
Route of administration
A route of administration in pharmacology and toxicology is the path by which a drug, fluid, poison, or other substance is taken into the body.-Classification:Routes of administration are usually classified by application location...
for medical substances.
In infants with biliary atresia
Biliary atresia
Biliary atresia, also known as "extrahepatic ductopenia" and "progressive obliterative cholangiopathy" is a congenital or acquired disease of the liver and one of the principle forms of chronic rejection of a transplanted liver allograft. As a birth defect in newborn infants, it has an occurrence...
, hepatoportoenterostomy
Hepatoportoenterostomy
A hepatoportoenterostomy, or Kasai portoenterostomy is a surgical treatment performed on infants with biliary atresia to allow for bile drainage...
is an alternative method of providing bile drainage.