Biliary tract

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Biliary tree
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Biliary tract
Ducts of the biliary tract
Details
FunctionFacilitate movement of bile, which aids in fat absorption
Identifiers
MeSHD001659
FMA79646
Anatomical terminology

The biliary tract (also biliary tree or biliary system) refers to the

conjugated bilirubin.[2] Some components are synthesized by hepatocytes (liver cells); the rest are extracted from the blood by the liver.[3]

Bile is secreted by the liver into small ducts that join to form the common hepatic duct.[4] Between meals, secreted bile is stored in the gallbladder.[5] During a meal, the bile is secreted into the duodenum (part of the small intestine) to rid the body of waste stored in the bile as well as aid in the absorption of dietary fats and oils.[5]

Structure

Accessory pancreatic duct, 17. Pancreatic duct.
18. Small intestine: 19. Duodenum, 20. Jejunum
21–22. Right and left kidneys.
The front border of the liver has been lifted up (brown arrow).[6]

The biliary tract refers to the path by which bile is secreted by the liver then transported to the

portal triad.[7] Bile flows in the direction opposite to that of the blood present in the other two channels.[8]

The system is usually referred to as the biliary tract or system,[9] and can include the use of the term "hepatobiliary" when used to refer just to the liver and bile ducts.[1] The name biliary tract is used to refer to all of the ducts, structures and organs involved in the production, storage and secretion of bile.[10]

The tract is as follows:

Function

Bile is secreted by the liver into small ducts that join to form the

bile acids.[5]

Clinical significance

Union of common bile duct and pancreatic duct terminating at duodenum (small intestine).

cholelithiasis, is very common in the United States, impacting over 20 million people.[11]

Gallstones frequently occur without causing symptoms– this is known as

asymptomatic cholelithiasis.[11] Sometimes gallstones may get stuck in the cystic duct, which serves as a bridge between the gallbladder and the common bile duct, and can lead to inflammation in the wall of the gallbladder.[11] This inflammation of the gallbladder is known as cholecystitis and is a common indication for surgical removal of the gallbladder, or cholecystectomy.[12]

Occasionally gallstones may become lodged in the common bile duct and obstruct the flow of bile from the gallbladder to the small intestine– this condition is known as

acute cholangitis and is commonly associated with a triad of clinical symptoms known as Charcot's Triad, which includes fever, right upper quadrant abdominal pain, and jaundice.[11] This constellation of symptoms has a 96% specificity for cholangitis,[11] and can be expanded upon with the addition of hypotension and altered mental status to form Reynold's Pentad.[11]

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, and biliary colic 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 obstructions.[13]

Chronic inflammatory conditions of the biliary tract, including Primary Sclerosing Cholangitis (PSC) and Primary Biliary Cirrhosis (PBC), can lead to hardening of the ducts in the biliary tree.[14]

An obstruction of the biliary tract can result in jaundice, a yellowing of the skin and whites of the eyes.[15]

References

  1. ^
    ISBN 978-1-4160-6257-8
    .
  2. ^
    PMID 29262229
    , retrieved 2022-11-14
  3. ISBN 978-0275972837
    .
  4. ^
    PMID 18992589
    .
  5. ^
    PMID 29494095
    , retrieved 2022-11-03
  6. ISBN 978-0-8089-2371-8
    .
  7. PMID 7473903
    .
  8. PMID 12529265
    .
  9. ^ Biliary+tract at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
  10. ISBN 978-1-4160-6257-8
    .
  11. ^
    PMID 33478678
    .
  12. ^
    PMID 28846328
    , retrieved 2022-11-03
  13. PMID 25540231
    .
  14. PMID 10980934
    .
  15. ^ "Definition: biliary tract". Online Medical Dictionary.
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