The Galle (Middle High German bile : gallbladder and their contents; gr. Χολή cholé ; lat. Bilis ) is a tough body fluid , which in the liver is produced before it in the gallbladder saved and at meals in the duodenum is distributed (duodenum) . Their color changes depending on the proportion of the main bile pigments bilirubin and biliverdin from yellowish to greenish. Heavily thickened, it takes on a brownish tone.
The bile is used to digest fat by emulsifying lipids , that is , breaking them down into small droplets that can be attacked by fat-splitting enzymes ( lipases ). Furthermore, the bile is an excretion medium for substances that are sparingly water-soluble and which are brought into a form that can be eliminated in the liver.
Colloquially , “bile” also refers to the bile juice and the gall bladder ; Common language dictionaries therefore give both the gallbladder and the bile as the meaning of bile . The movement of the bile in the bile ducts, including the associated movements of the gallbladder and bile ducts, is known as cholekinesis .
|Na +||130-165 mmol / L|
|K +||3-12 mmol / l|
|Cl -||90-120 mmol / l|
|HCO 3 -||30 mmol / l|
Bile consists mostly of water (82%), in which inorganic electrolytes are dissolved in a composition similar to that in blood plasma (see table on the right). Bile is slightly alkaline . The most important functional components, however, are the bile salts (12%), which play a central role in fat digestion. It also contains alkaline phosphatases , a group of enzymes that hydrolyze phosphoric acid esters .
The bile also contains lecithin and other phospholipids (4%), non- esterified cholesterol (0.7%) and degradation products from the liver, which pass through the bile into the digestive tract and are excreted with the feces. The latter include bilirubin , the breakdown product of the blood pigment hemoglobin , as well as some hormones and drugs.
The bile gets its color mainly from the bile pigments : the yellowish to red bilirubin, depending on the concentration, and the greenish biliverdin . Bilirubin is broken down in the intestine by the bacteria resident there to form stercobilin , bilifuscin and mesobilifuscin , among other things , which give the stool its characteristic color.
The transport of cholesterol in the bile takes place in micelles , which are formed from lecithin, cholesterol and bile salts. The mixing ratio of these three substances may only fluctuate within very narrow limits so that the cholesterol transport can function. Otherwise, the cholesterol will crystallize and gallstones will form .
The human body produces around 700 ml of bile per day, which is stored in the gallbladder interdigestively, i.e. between meals .
Bile is in the cells of the liver , the hepatocytes produced. The bile ducts ( canaliculi ), into which the bile is excreted by transmembrane transport , are located between two neighboring hepatocytes . These canaliculi combine to form larger canals that ultimately carry the bile to the digestive tract (see below).
Substances secreted into the canaliculi are lecithin, conjugated bile salts, cholesterol, hormones conjugated with glucuronic acid, and bilirubin. Drugs conjugated with glutathione can also be excreted in the bile. The hepatocytes extract the conjugated bile salts from the sinusoids, microscopic blood vessels that transport blood to the hepatocytes.
The liver cells have transport proteins ( carriers ) especially for bile salts in their cell membranes, which are adjacent to the sinusoids as well as the canaliculi . They are actively absorbed from the sinusoids with the help of a sodium symport transport protein (NTCP = Na + -taurocholate cotransporting polypeptide ) , while they are primarily actively taken up with the help of an ATP- dependent transporter (hBSEP: human bile salt export pump , also cBAT: canalicular bile acid transporter ) in the lumen of the canaliculi.
Transportation and storage
The extrahepatic (outside of the liver) bile ducts begin with the common hepatic duct (common liver duct), from which the cystic duct (gall bladder duct , connection between the gall bladder and main bile duct ) branches off to the gall bladder. The section after this branch is called the ductus choledochus and finally joins the ductus pancreaticus of the pancreas into the duodenum on the papilla duodeni major .
The bile is stored in the gallbladder and thickened to around ten percent of its volume. If lipids get into the small intestine with food, they stimulate the production of the hormone cholecystokinin (CCK) in the small intestinal mucosa. CCK stimulates the smooth muscles in the organ wall of the gallbladder, so that it contracts and its contents are mixed with the chyme in the duodenum. Increased activity of the parasympathetic vagus nerve ( vagotonus ) has the same effect. However, not all vertebrates have a gallbladder.
The bile plays an important role in the processing of fats from the food and contributes to the neutralization of the food, which is strongly acidic after passage through the stomach. It is also used to eliminate various substances from the body such as cholesterol , bilirubin and many drugs and their metabolic products. The formation of bile is essential for the balance of cholesterol in the body.
The bile salts are used for fat digestion by forming micelles with the water-insoluble components of food ( triacylglycerides , free fatty acids , vitamins and cholesterol) and thus enabling their transport in the blood . Medicines and their breakdown products are conjugated with glutathione and thus made water-soluble, and then excreted with the bile through the digestive tract and ultimately the feces. This also applies to metabolic products such as bilirubin, which arises from the breakdown of hemoglobin in the liver cells. Other tasks are the excretion of heavy metals , the neutralization of the duodenum after gastric emptying and the activation of the pancreatic enzymes . Bile acids also have a bactericidal effect , i.e. they kill bacteria.
Bile salts cycle
Bile salts are divided into primary and secondary bile salts. The primary bile salts, cholate and chenodeoxycholate , are synthesized from cholesterol by the liver. These are partially converted by bacteria in the digestive tract into secondary bile salts, deoxycholate and lithocholate . The bile salts are then deconjugated in the digestive tract, absorbed by the mucous membrane and , bound to albumin , transported back to the liver in the portal vein ( vena portae ) . There they are absorbed, re- conjugated with taurine and glycine, and again excreted in the bile. This cycle is known as the enterohepatic bile salt cycle and ensures that the body's bile salt inventory of just two to four grams can meet the fat absorption requirements of 20–30 g. It circulates five to ten times a day. Only about 0.3-0.6 g of bile salts are lost and have to be re-synthesized in the liver. Bile salts that are not conjugated with taurine or glycine are immediately reabsorbed, while those that are conjugated only take part in fat digestion in the ileum (ileum).
The symptoms that occur in humans with a disturbance of bile formation or bile secretion can be explained by their functions in fat digestion and the excretion of end products of the metabolism. A blockage of the biliary tract with retention of bile is called cholestasis in medical parlance . In this case, there is a fat intolerance, as this can only be absorbed from the intestine to a small extent. Higher fat intake in food leads to fatty stools ( steatorrhea ). Furthermore, so-called posthepatic jaundice (jaundice) occurs because the hemoglobin breakdown product bilirubin, a yellow pigment, can no longer be properly excreted and causes yellowing of the skin and mucous membranes. Due to the lack of bile pigments, the stool takes on a clay-like color known as acholic . These blockages can have various causes such as tumors of the pancreas, gallbladder, bile ducts or the duodenum. Gallstones in the common hepatic duct or common bile duct can be another cause . Obstructions of the cystic duct only rarely lead to a blockage of the bile discharge ( Mirizzi syndrome ).
Gallstones are crystallization products that arise when the mixing ratio between lecithin, cholesterol and the bile salts is out of balance. In the metabolic disorder erythropoietic protoporphyria , stones often arise from the heme precursor protoporphyrin IX . Symptoms only occur in about a quarter of all cases. These include colic , tenderness (tenderness) in the right upper abdomen and the jaundice mentioned above. In rare cases, there is also back pain.
Bile agar is obtained from bovine bile and is a nutrient medium used in microbiology . Depending on the substrate contained in addition to the bile, numerous germs such as streptococci , salmonella and shigella , but also fungi can be grown. If salmonella is to be enriched from a patient's blood, a bile broth consisting of three parts bile and one part blood is mixed. Salmonella can multiply in it.
The word Galle ( mhd . Galle , ahd . Galla ) is derived from the Indo-European root * ghel- , "yellow, green"; the bile is named after its color. From this root in Greek χολή ( cholé ) "bile" developed.
The cholera (χολέρα choléra "Bile diarrhea"), a caused by cholera or enteritis Salmonella enteritis, not its name originally due to the false assumption that it is caused by a bile disorder but derives rather from the Greek word cholera with the meanings Gutter ',' severe vomiting diarrhea 'or' biliary dysentery '.
In the humoral pathology of the Hippocrats , around 400 BC BC and determined medical teaching for over a thousand years, until it lost its importance with Paracelsus , the hot and dry body juice bile plays a central role. A distinction was made essentially between yellow bile (Latin cholera and Middle Latin colera , more precisely: cholera citrina ) and black bile ( melancholia ). Along with blood and mucus ("phlegm"), these two belong to the four so-called cardinal juices (→ four juices doctrine ). If these are in equilibrium ( eukrasia ), the person is healthy. An imbalance ( dyscrasia ) leads to illness. Yellow bile is produced in the liver and has been associated with choleric people and anger. According to the humoral pathology , black bile is produced in the testicles and the spleen and is associated with melancholics (from mélaina cholé , black bile). Proverbial expressions like “I get bile up” or “Spit poison and bile”, both metaphors for anger, are based on this teaching. More - in addition colera citrina , colera vitellina and colera nigra - in the Middle Ages (about the 1170 incurred Liber mitis of Guido d'Arezzo) distinct cholera -Erscheinungsformen were colera adusta , colera aeruginosa , colera flegmatica , colera prasina , colera Rubea and colera viridis .
- Manfred Dietel, Joachim Dudenhausen, Norbert Suttorp (eds.): Harrison's internal medicine. 15th edition. ABW Wissenschaftsverlag, Berlin 2003, ISBN 3-936072-10-8 .
- Eckhart G. Hahn, Jürgen F. Riemann : Clinical gastroenterology. Thieme, Stuttgart 1996, ISBN 3-13-477703-7 , pp. 1262-1269.
- Nikolaus Mani: The historical foundations of liver research, I: The ideas about anatomy, physiology and pathology of the liver in antiquity. Basel and Stuttgart 1959 (= Basel publications on the history of medicine and biology, 9), pp. 22, 28–34, 53–55 and 59.
- Robert F. Schmidt, Florian Lang, Gerhard Thews : Human Physiology. Springer, Berlin 2004, ISBN 3-540-21882-3 .
- See for example Jürgen Martin: The 'Ulmer Wundarznei'. Introduction - Text - Glossary on a monument to German specialist prose from the 15th century. Königshausen & Neumann, Würzburg 1991 (= Würzburg medical-historical research. Volume 52), ISBN 3-88479-801-4 (also medical dissertation Würzburg 1990), p. 129.
- See Galle und Gallensaft at Duden online.
- Georg Löffler, Petro E. Petrides: Biochemistry and Pathobiochemistry. 6th edition. Springer, Berlin 1998, ISBN 3-540-64350-8 .
- Stefan Silbernagl , Agamemnon Despopoulos : Pocket Atlas of Physiology. 6th edition. Thieme, Stuttgart 2003, ISBN 3-13-567706-0 , p. 248.
- Khalili MJ et al .: Erythropoietic protoporphyria and early onset of cholestasis. In: Turk J Pediatr. 2012 Nov-Dec; 54 (6): 645-50.
- See for example Jürgen Martin: The 'Ulmer Wundarznei'. Introduction - Text - Glossary on a monument to German specialist prose from the 15th century. Königshausen & Neumann, Würzburg 1991 (= Würzburg medical-historical research. Volume 52), ISBN 3-88479-801-4 (also medical dissertation Würzburg 1990), p. 123 ( colera ).
- Bruno Valentin : Cholera Letters. In: Sudhoff's archive. Volume 37, 1953, pp. 417-421, here: p. 417.
- Nikolaus Mani (1959)
- Konrad Goehl: The basics of galenics in a Florentine fragment of the 13th century. In: Konrad Goehl, Johannes Gottfried Mayer (Hrsg.): Editions and studies on Latin and German specialist prose of the Middle Ages. Festival ceremony for Gundolf Keil. Königshausen & Neumann, Würzburg 2000. ISBN 3-8260-1851-6 , pp. 17–53, here: p. 36.