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Bile (yellow material) in a liver biopsy in the setting of bile stasis, i.e. cholestasis. H&E stain.

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 between meals and upon eating is discharged into the duodenum.

In the medical theories prevalent in the West from Classical Antiquity up to the Middle Ages, the body's health depended on the equilibrium between four "humors" or vital fluids: blood, phlegm, "yellow bile" (or ichor) and "black bile". Excesses of the last two humors were supposed to produce aggression and depression, respectively; and the Greek names for them gave rise to the English words "cholera" and "melancholia". Those same theories explain the derivation of the English word "bilious" from "bile", and the alternate meaning of "gall" in English as "exasperation" or "impudence".

Contents


Constituents

Composition of bile
Constituent Intrahepatic In gallbladder Unit
pH 7.5 6.0
Na+ 141-165 220 mM
K+ 2.7-6.7 14 mM
Ca2+ 1.2-3.2 15 mM
Cl- 77-117 31 mM
HCO3- 12-55 19 mM
Total phosphorus 0.15 1.4 g/L
Bile acids 3-45 32 g/L
Total fatty acids 2.7 24 g/L
Bilirubin 1-2 3 g/L
Phospholipids 1.4-8.1 34 g/L
Cholesterol 1-3.2 6.3 g/L
Proteins 2-20 4.5 g/L
Unless else specified in boxes, then source is [1]

Bile has various components, some of which are produced by hepatocytes in the liver. The main components include:

The most important compounds are the anions of the bile acids, taurocholic acid and deoxycholic acid.

The bile acids are typically conjugated with taurine, or glycine and are produced by the liver from cholesterol. They are secreted in bile by hepatocytes along the bile canaliculi, which then join the bile duct, and hence into the gallbladder. Ordinarily the concentration of bile salts in bile is 0.8%, however the gallbladder removes water from the bile, concentrating it between meals. It concentrates it up to 5 times (increasing concentration to 4%), before contracting the walls and releasing it into the duodenum once chyme has entered the small intestine from the stomach.

Production

Digestive system diagram showing the bile duct

Bile is produced by hepatocytes in the liver, draining through the many bile ducts that penetrate the liver. During this process, the epithelial cells add a watery solution that is rich in bicarbonates that dilutes and increases alkalinity of the solution. Bile then flows into the common hepatic duct, which joins with the cystic duct from the gallbladder to form the common bile duct. The common bile duct in turn joins with the pancreatic duct to empty into the duodenum. If the sphincter of Oddi is closed, bile is prevented from draining into the intestine and instead flows into the gallbladder, where it is stored and concentrated to up to five times its original potency between meals. This concentration occurs through the absorption of water and small electrolytes, while retaining all the original organic molecules. Cholesterol is also released with the bile, dissolved in the acids and fats found in the concentrated solution. When food is released by the stomach into the duodenum in the form of chyme, the duodenum releases cholecystokinin, which causes the gallbladder to release the concentrated bile to complete digestion.

The human liver can produce close to one litre of bile per day (depending on body size). About 95% of the salts secreted in bile are reabsorbed in the terminal ileum and re-used. Blood from the ileum flows directly to the hepatic portal vein and returns to the liver where the hepatocytes reabsorb the salts and return them to the bile ducts to be re-used, sometimes two to three times with each meal.

Physiological functions

Action of bile salts in digestion

Bile acts to some extent as a surfactant, helping to emulsify the fats in the food. Bile salt anions have a hydrophilic side and a hydrophobic side, and therefore tend to aggregate around droplets of fat (triglycerides and phospholipids) to form micelles, with the hydrophobic sides towards the fat and hydrophilic towards the outside. The hydrophilic sides are positively charged due to the lecithin and other phospholipids that compose bile, and this charge prevents fat droplets coated with bile from re-aggregating into larger fat particles. Ordinarily, the micelles in the duodenum have a diameter of around 14-33 μm.

The dispersion of food fat into micelles thus provide a largely increased surface area for the action of the enzyme pancreatic lipase, which actually digests the triglycerides, and is able to reach the fatty core through gaps between the bile salts. A triglyceride is broken down into two fatty acids and a monoglyceride, which are absorbed by the villi on the intestine walls. Without bile salts, most of the lipids in the food would be passed out in feces, undigested.

Since bile increases the absorption of fats, it is an important part of the absorption of the fat-soluble substances, such as the vitamins D, E, K and A.

Besides its digestive function, bile serves also as the route of excretion for bilirubin, a byproduct of red blood cells recycled by the liver. Bilirubin derives from hemoglobin by glucuronidation.

The alkaline bile also has the function of neutralizing any excess stomach acid before it enters the ileum, the final section of the small intestine. Bile salts also act as bactericides, destroying many of the microbes that may be present in the food.

Bile soap

Bile from slaughtered animals can be mixed with soap. This mixture, called bile soap,[2] can be applied to textiles a few hours before washing and is a traditional and rather effective method for removing various kinds of tough stains.

Abnormal conditions associated with bile

  • The cholesterol contained in bile will occasionally accrete into lumps in the gall bladder, forming gallstones.
  • On an empty stomach – after repeated vomiting, for example – a person's vomit may be green or dark yellow, and very bitter. The bitter and greenish component is bile.[citation needed] (The color of bile is often likened to "fresh-cut grass", but in a vomit it may be mixed with other components in the stomach to look greenish yellow or dark yellow.)

See also

Footnotes

  1. ^ Unless else specified: Walter F., PhD. Boron (2003). Medical Physiology: A Cellular and Molecular Approach. Elsevier/Saunders. pp. 1300. ISBN 1-4160-2328-3. 
  2. ^ NEWTON, W. (1837). "The invention of certain improvements in the manufacture of soap, which will be particularly applicable to the felting of woollen cloths.". The London Journal Of Arts And Sciences; And Repertory Of Patent Inventions IX: 289. http://www.google.co.uk/books?vid=0MfyvmoTsdK02ZeP86W&id=GhMAAAAAMAAJ&pg=RA19-PA291&lpg=RA19-PA291&dq=bile+soap&as_brr=1. Retrieved 2007-02-08. 
  3. ^ Barabote RD, Tamang DG, Abeywardena SN, et al. (2006). "Extra domains in secondary transport carriers and channel proteins". Biochim. Biophys. Acta 1758 (10): 1557–79. doi:10.1016/j.bbamem.2006.06.018. PMID 16905115. 

References

  1. ^ Unless else specified: Walter F., PhD. Boron (2003). Medical Physiology: A Cellular and Molecular Approach. Elsevier/Saunders. pp. 1300. ISBN 1-4160-2328-3. 
  2. ^ NEWTON, W. (1837). "The invention of certain improvements in the manufacture of soap, which will be particularly applicable to the felting of woollen cloths.". The London Journal Of Arts And Sciences; And Repertory Of Patent Inventions IX: 289. http://www.google.co.uk/books?vid=0MfyvmoTsdK02ZeP86W&id=GhMAAAAAMAAJ&pg=RA19-PA291&lpg=RA19-PA291&dq=bile+soap&as_brr=1. Retrieved 2007-02-08. 
  3. ^ Barabote RD, Tamang DG, Abeywardena SN, et al. (2006). "Extra domains in secondary transport carriers and channel proteins". Biochim. Biophys. Acta 1758 (10): 1557–79. doi:10.1016/j.bbamem.2006.06.018. PMID 16905115. 

External links


Wiktionary

Up to date as of January 15, 2010
(Redirected to bile article)

Definition from Wiktionary, a free dictionary

Contents

English

Pronunciation

Etymology

Mid 16th century, via French, from Latin bīlis (bile).

Noun

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Wikipedia

Singular
bile

Plural
uncountable

bile (uncountable)

  1. (biochemistry) A bitter brownish-yellow or greenish-yellow secretion produced by the liver, stored in the gall bladder, and discharged into the duodenum where it aids the process of digestion.
  2. bitterness of temper; ill humour; irascibility.
  3. Two of the four humours, black bile or yellow bile, in ancient and medieval physiology.

Synonyms

Derived terms

Translations


French

Pronunciation

Noun

bile f (usually uncountable)

  1. bile

Italian

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Bile

Wikipedia it

Pronunciation

  • IPA: /ˈbile/

Noun

bile f. (plural bili)

  1. (physiology) bile

Derived terms

Anagrams

  • Anagrams of beil
  • beli

Old Irish

Etymology

From Proto-Celtic *belyo- (tree) < Proto-Indo-European *bholyo- (leaf).

Noun

bile

  1. tree

Descendants


Scottish Gaelic

Noun

bile f. (genitive bile, plural bilean )

  1. A lip of the mouth.
    Thàinig faite-gàire bheag gu a bhilean. — A small smile came to her lips.

Turkish

Conjunction

bile

  1. neither, even

West Frisian

Noun

bile (pl. bilen)

  1. axe

Simple English

Bile or gall is a green-yellow fluid. It is secreted from the liver of most vertebrate animals, and is often stored in the gall bladder. Bile helps digest fat.

The components of bile are

The name gall comes from the Greek word cholè meaning green or yellow. The term cholesterol and the illness cholera were named after gall. Bile is also stored in bile ducts. Often after liver transplants, bile comes out of the body








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