Gallbladder

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Gallbladder
Illu pancrease.svg
Diagram of Stomach
Surface projections of the organs of the trunk.png
Surface projections of the organs of the trunk, with gallbladder labeled at the transpyloric plane
LatinVesica biliaris, vesica fellea
Gray'ssubject #250 1197
SystemDigestive system
ArteryCystic artery
VeinCystic vein
NerveCeliac ganglia, vagus[1]
PrecursorForegut
 
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Gallbladder
Illu pancrease.svg
Diagram of Stomach
Surface projections of the organs of the trunk.png
Surface projections of the organs of the trunk, with gallbladder labeled at the transpyloric plane
LatinVesica biliaris, vesica fellea
Gray'ssubject #250 1197
SystemDigestive system
ArteryCystic artery
VeinCystic vein
NerveCeliac ganglia, vagus[1]
PrecursorForegut
1. Bile ducts: 2. Intrahepatic bile ducts, 3. Left and right hepatic ducts, 4. Common hepatic duct, 5. Cystic duct, 6. Common bile duct, 7. Ampulla of Vater, 8. Major duodenal papilla
9. Gallbladder, 10–11. Right and left lobes of liver. 12. Spleen.
13. Esophagus. 14. Stomach. Small intestine: 15. Duodenum, 16. Jejunum
17. Pancreas: 18: Accessory pancreatic duct, 19: Pancreatic duct.
20–21: Right and left kidneys (silhouette).
The anterior border of the liver is lifted upwards (brown arrow). Gallbladder with Longitudinal section, pancreas and duodenum with frontal one. Intrahepatic ducts and stomach in transparency.

In vertebrates the gallbladder (cholecyst, gall bladder or biliary vesicle) is a small organ where bile is stored, before it is released into the small intestine. Humans can live normal lives without a gallbladder. The surgical removal of the gallbladder is called a cholecystectomy.

Structure[edit]

The gallbladder is a hollow system that sits just beneath the liver.[2] In adults, the gallbladder measures approximately 8 centimetres (3.1 in) in length and 4 centimetres (1.6 in) in diameter when fully distended.[3] It is divided into three sections: fundus, body and neck. The neck tapers and connects to the biliary tree via the cystic duct, which then joins the common hepatic duct to become the common bile duct. At the neck of the gallbladder is a mucosal fold called Hartmann's pouch, where gallstones commonly get stuck. The angle of the gallbladder is located between the costal margin and the lateral margin of the rectus abdominis muscle. The fundus is at the same level as the transpyloric plane; the body is attached to the liver.

Histology[edit]

The different layers of the gallbladder are as follows:[4]

Unlike elsewhere in the intestinal tract, the gallbladder does not have a muscularis mucosae.

Function[edit]

The main purpose of the gallbladder is to store bile, or gall. The gallbladder is part of the biliary system and serves as a reservoir for bile, which is produced by the liver. The liver produces the bile and then it flows through the bile ducts into the gallbladder. The gallbladder releases the bile in response to a hormone called cholecystokinin, which is released from the small intestine. When the bile is released, it is released into the small intestine and its purpose is to break down large fat molecules into smaller ones. After the fat is absorbed, the bile is also absorbed and transported back to the liver for reuse.

When food containing fat (and amino acids) enters the digestive tract, it stimulates the secretion of cholecystokinin (CCK) from I cells of the duodenum and jejunum. In response to CCK, the adult human gallbladder, which stores about 50 millilitres (1.7 U.S. fl oz; 1.8 imp fl oz) of bile, contracts and releases its contents into the duodenum. The bile, originally produced in the liver, emulsifies fats in partly digested food.

During storage in the gallbladder, bile becomes more concentrated which increases its potency and intensifies its effect on fats.

In 2009, it was proposed that the gallbladder can produce several pancreatic hormones, including insulin.[5]

Clinical significance[edit]

Gallstone[edit]

"By far, the most common gallbladder problem is Gallstones" (Rodriguez). The gallbladder is supposed to store bile in a natural, semi-liquid form at all times. Hydrogen ions secreted from the inner lining of the gallbladder are supposed to keep the bile acidic enough to prevent hardening. To dilute the bile, water and electrolytes from the digestion system are added. Also, salts attach themselves to cholesterol molecules in the bile to keep them from crystallizing. Sometimes there can be too much cholesterol or bilirubin in the bile, or the gallbladder doesn't empty like it should and the systems listed above fail. This is how gallstones form. All it takes is a tiny bit of calcium to get coated with either cholesterol or bilirubin and crystallization of the bile, to form a gallstone. Gallstones are dangerous because they may never cause any pain or symptoms until they are causing a problem in the biliary system.

Gallbladder removal[edit]

The recurrence rate of gallstone related issues is very high, so elective surgical resection of the gallbladder is the standard of care after such issues. This is fine because the digestive system will still be able to function properly .[citation needed] The gallbladder does not produce anything needed for digestion, it simply stores bile until digestion, when it is released into the small intestine. With no gallbladder, bile will just continuously drip from the liver during digestion for the breakdown of fats. Patients undergoing a cholecystectomy seldom have long-term post-surgical issues with the function of their digestive system .[citation needed]

A traditional cholecystectomy is most commonly performed from the infundibulum to the fundus.[6]

In other animals[edit]

Most vertebrates have gallbladders, whereas invertebrates do not. However, its precise form and the arrangement of the bile ducts may vary considerably. In many species, for example, there are several separate ducts running to the intestine, rather than a single common bile duct, as in humans. Several species of mammals (including horses, deer, rats, and various laminis[7]) and several species of birds lack a gallbladder altogether, as do lampreys.[8]

See also[edit]

References[edit]

  1. ^ Ginsburg, Ph.D., J.N. (2005-08-22). "Control of Gastrointestinal Function". In Thomas M. Nosek, Ph.D. Gastrointestinal Physiology. Essentials of Human Physiology. Augusta, Georgia, United State: Medical College of Georgia. pp. p. 30. Retrieved 2007-06-29. 
  2. ^ "Where is the Gallbladder Located in the Body". Buzzle.com. 2013-02-28. Retrieved 2013-08-18. 
  3. ^ Jon W. Meilstrup (1994). Imaging Atlas of the Normal Gallbladder and Its Variants. Boca Raton: CRC Press. p. 4. ISBN 0-8493-4788-2. 
  4. ^ "Staging of Gallbladder Cancer". 
  5. ^ Sahu, S.; Joglekar, M. V.; Dumbre, R.; Phadnis, S. M.; Tosh, D.; Hardikar, A. A. (2009). "Islet-like cell clusters occur naturally in human gall bladder and are retained in diabetic conditions". Journal of Cellular and Molecular Medicine 13 (5): 999–1000. doi:10.1111/j.1582-4934.2008.00572.x . PMID 19175681.  edit
  6. ^ Neri V, Ambrosi A, Fersini A, Tartaglia N, Valentino TP (2007). "Antegrade dissection in laparoscopic cholecystectomy". JSLS : Journal of the Society of Laparoendoscopic Surgeons / Society of Laparoendoscopic Surgeons 11 (2): 225–8. PMC 3015719. PMID 17761085. 
  7. ^ C. Michael Hogan. 2008. Guanaco: Lama guanicoe, GlobalTwitcher.com, ed. N. Strömberg
  8. ^ Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. p. 355. ISBN 0-03-910284-X. 

External links[edit]