AskDefine | Define liver

Dictionary Definition

liver

Noun

1 large and complicated reddish-brown glandular organ located in the upper right portion of the abdominal cavity; secretes bile and functions in metabolism of protein and carbohydrate and fat; synthesizes substances involved in the clotting of the blood; synthesizes vitamin A; detoxifies poisonous substances and breaks down worn-out erythrocytes
2 liver of an animal used as meat
3 a person who has a special life style; "a high liver"
4 someone who lives in a place; "a liver in cities"

User Contributed Dictionary

English

Pronunciation

Noun

  1. A large organ in the body that stores and metabolizes nutrients, destroys toxins and produces bile. Responsible for thousands of biochemical reactions.
  2. This livestock organ used as food.
  3. A dark brown colour, tinted with red and gray, like that of liver.
    liver colour:   

Derived terms

Translations

organ of the body
organ as food
  • Dutch: lever , levertjes m, dim, pl
  • Erzya: максо (makso)
  • Finnish: maksa
  • French: foie
  • Greek: συκώτι
  • Icelandic: lifur
  • Indonesian: hati
  • Italian: fegato
  • Japanese: レバー (rebā)
  • Kurdish:
  • Latvian: aknas f|p
  • Lithuanian: kepenys p
  • Maltese: fwied
  • Portuguese: fígado
  • Russian: печень
  • Slovene: jetrca n pl
  • Swedish: lever
colour

Adjective

(the noun as a modifier) liver (no or forms)
  1. Concerning or relating to the liver.
    liver transplant
  2. Intended for the liver.
    liver salts
  3. Of food, made of liver.
    liver pâté

Translations

concerning the liver
  • Dutch: lever- (in compounds)
  • Finnish: maksa- (in compounds)
  • French: de foie
  • Greek: ηπατικός
  • Irish: ae
  • Italian: di fegato
  • Swedish: lever-
intended for the liver
made of liver
  • Dutch: lever- (in compounds)
  • Finnish: maksa- (in compounds)
  • French: de foie
  • Hungarian: májas
  • Italian: di fegato
  • Swedish: lever
colour
  • Hungarian: májszínű

Breton

Noun

liver

Extensive Definition

The liver is the largest internal organ in the human body, and is an organ present in vertebrates and some other animals. The liver is necessary for survival, a human can only last up to 24 hours without liver function. It plays a major role in metabolism and has a number of functions in the body, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, and detoxification. The liver is also the largest gland in the human body. It lies below the diaphragm in the thoracic region of the abdomen. It produces bile, an alkaline compound which aids in digestion, via the emulsification of lipids. It also performs and regulates a wide variety of high-volume biochemical reactions requiring very specialized tissues.
Medical terms related to the liver often start in hepato- or hepatic from the Greek word for liver, hēpar (ήπαρ).

Anatomy

The adult human liver normally weighs between 1.4 - 1.6 kilograms (3.1 - 3.5 pounds), and it is a soft, pinkish-brown, triangular organ. Averaging about the size of an American football in adults, it is both the largest internal organ and the largest gland in the human body.
It is located on the right side of the upper abdomen below the diaphragm anatomy. The liver lies to the right of the stomach and overlies the gallbladder.

Flow of blood

The splenic vein joins the inferior mesenteric vein, which then together join the superior mesenteric vein to form the hepatic portal vein, bringing venous blood from the spleen, pancreas, stomach, small intestine, and large intestine, so that the liver can process the nutrients and by-products of food digestion.
The hepatic veins of the blood can be from other branches such as the superior mesenteric artery.
Both the portal venules & the hepatic arterioles enter approximately one million identical lobules acini, likened to and changes in the size of chylomicrons lipoproteins of dietary origin brought about by the quantity & types of food fats.
Approximately 60% to 80% of the blood flow to the liver is from the portal venous system, and 1/4 is from the hepatic artery.

Flow of bile

The bile produced in the liver is collected in bile canaliculi, which merge to form bile ducts.
These eventually drain into the right and left hepatic ducts, which in turn merge to form the common hepatic duct. The cystic duct (from the gallbladder) joins with the common hepatic duct to form the common bile duct.
Bile can either drain directly into the duodenum via the common bile duct or be temporarily stored in the gallbladder via the cystic duct. The common bile duct and the pancreatic duct enter the duodenum together at the ampulla of Vater.
The branchings of the bile ducts resemble those of a tree, and indeed the term "biliary tree" is commonly used in this setting.

Regeneration

The liver is among the few internal human organs capable of natural regeneration of lost tissue; as little as 25% of remaining liver can regenerate into a whole liver again.
This is predominantly due to the hepatocytes reentering the cell cycle (i.e. the hepatocytes go from the quiescent G0 phase to the G1 phase and undergo mitosis). There is also some evidence of bipotential stem cells, called ovalocyte (o´və-lo-sīt), which exist in the Canals of Hering. These cells can differentiate into either hepatocytes or cholangiocytes (cells that line the bile ducts).

Traditional (Surface) anatomy

Peritoneal ligaments

Apart from a patch where it connects to the diaphragm, the liver is covered entirely by visceral peritoneum, a thin, double-layered membrane that reduces friction against other organs. The peritoneum folds back on itself to form the falciform ligament and the right and left triangular ligaments.
These "ligaments" are in no way related to the true anatomic ligaments in joints, and have essentially no functional importance, but they are easily recognizable surface landmarks.

Lobes

Traditional gross anatomy divided the liver into four lobes based on surface features. The falciform ligament is visible on the front (anterior side) of the liver. This divides the liver into a left anatomical lobe, and a right anatomical lobe.
If the liver flipped over, to look at it from behind (the visceral surface), there are two additional lobes between the right and left. These are the caudate lobe (the more superior), and below this the quadrate lobe.
From behind, the lobes are divided up by the ligamentum venosum and ligamentum teres (anything left of these is the left lobe), the transverse fissure (or porta hepatis) divides the caudate from the quadrate lobe, and the right sagittal fossa, which the inferior vena cava runs over, separates these two lobes from the right lobe.
Each of the lobes is made up of lobules, a vein goes from the centre of each lobule which then joins to the hepatic vein to carry blood out from the liver.
On the surface of the lobules there are ducts, veins and arteries that carry fluids to and from them.

Modern (Functional) anatomy

The central area where the common bile duct, hepatic portal vein, and hepatic artery enter is the hilum or "porta hepatis". The duct, vein, and artery divide into left and right branches, and the portions of the liver supplied by these branches constitute the functional left and right lobes.
The liver performs over 500 jobs, and produces over 1,000 essential enzymes.
The functional lobes are separated by a plane joining the gallbladder fossa to the inferior vena cava. This separates the liver into the true right and left lobes. The middle hepatic vein also demarcates the true right and left lobes. The right lobe is further divided into an anterior and posterior segment by the right hepatic vein. The left lobe is divided into the medial and lateral segments by the left hepatic vein. The fissure for the ligamentum teres (the ligamentum teres becomes the falciform ligament) also separates the medial and lateral segments. The medial segment is what used to be called the quadrate lobe. In the widely used Couinaud or "French" system, the functional lobes are further divided into a total of eight subsegments based on a transverse plane through the bifurcation of the main portal vein. The caudate lobe is a separate structure which receives blood flow from both the right- and left-sided vascular branches. The subsegments corresponding to the anatomical lobes are as follows:
  • or lobe in the Caudate's case.
Each number in the list corresponds to one in the table.
Caudate Superior subsegment of the lateral segment Inferior subsegment of the lateral segment
Superior subsegment of the medial segment Inferior subsegment of the medial segment
Inferior subsegment of the anterior segment Inferior subsegment of the posterior segment Superior subsegment of the posterior segment Superior subsegment of the anterior segment

Physiology

The various functions of the liver are carried out by the liver cells or hepatocytes. Currently, there is no artificial organ or device capable of emulating all the functions of the liver. Some functions can be emulated by liver dialysis, an experimental treatment for liver failure.

Diseases of the liver

Many diseases of the liver are accompanied by jaundice caused by increased levels of bilirubin in the system. The bilirubin results from the breakup of the hemoglobin of dead red blood cells; normally, the liver removes bilirubin from the blood and excretes it through bile.
There are also many pediatric liver disease, including biliary atresia, alpha-1 antitrypsin deficiency, alagille syndrome, and progressive familial intrahepatic cholestasis, to name but a few.

Herbal Treatments

The most commonly used herbs for liver problems include Milk Thistle, Dandelion Root, Licorice Root, and Chicory root.
Milk Thistle is the best studied herb for hepatitis, and has shown to help protect and regenerate liver cells.

Liver transplantation

Human liver transplant was first performed by Thomas Starzl in USA and Roy Calne in Cambridge, England in 1963 and 1965 respectively.
Liver transplantation is the only option for those with irreversible liver failure. Most transplants are done for chronic liver diseases leading to cirrhosis, such as chronic hepatitis C, alcoholism, autoimmune hepatitis, and many others. Less commonly, liver transplantation is done for fulminant hepatic failure, in which liver failure occurs over days to weeks.
Liver allografts for transplant usually come from non-living donors who have died from fatal brain injury. Living donor liver transplantation is a technique in which a portion of a living person's liver is removed and used to replace the entire liver of the recipient. This was first performed in 1989 for pediatric liver transplantation. Only 20% of an adult's liver (Couinaud segments 2 and 3) is needed to serve as a liver allograft for an infant or small child.
More recently, adult-to-adult liver transplantation has been done using the donor's right hepatic lobe which amounts to 60% of the liver. Due to the ability of the liver to regenerate, both the donor and recipient end up with normal liver function if all goes well. This procedure is more controversial as it entails performing a much larger operation on the donor, and indeed there have been at least 2 donor deaths out of the first several hundred cases. A recent publication has addressed the problem of donor mortality, and at least 14 cases have been found. The risk of postoperative complications (and death) is far greater in right sided hepatectomy than left sided operations.
With the recent advances of non-invasive imaging, living liver donors usually have to undergo imaging examinations for liver anatomy to decide if the anatomy is feasible for donation. The evaluation is usually performed by multi-detector row computed tomography (MDCT) and magnetic resonance imaging (MRI). MDCT is good in vascular anatomy and volumetry. MRI is used for biliary tree anatomy. Donors with very unusual vascular anatomy, which makes them unsuitable for donation, could be screened out to avoid unnecessary operation.

Development

Fetal blood supply

In the growing fetus, a major source of blood to the liver is the umbilical vein which supplies nutrients to the growing fetus. The umbilical vein enters the abdomen at the umbilicus, and passes upward along the free margin of the falciform ligament of the liver to the inferior surface of the liver. There it joins with the left branch of the portal vein. The ductus venosus carries blood from the left portal vein to the left hepatic vein and then to the inferior vena cava, allowing placental blood to bypass the liver.
In the fetus, the liver develops throughout normal gestation, and does not perform the normal filtration of the infant liver. The liver does not perform digestive processes because the fetus does not consume meals directly, but receives nourishment from the mother via the placenta. The fetal liver releases some blood stem cells that migrate to the fetal thymus, so initially the lymphocytes, called T-cells, are created from fetal liver stem cells. Once the fetus is delivered, the formation of blood stem cells in infants shifts to the red bone marrow.
After birth, the umbilical vein and ductus venosus are completely obliterated two to five days postpartum; the former becomes the ligamentum teres and the latter becomes the ligamentum venosum. In the disease state of cirrhosis and portal hypertension, the umbilical vein can open up again.

Liver as food

Mammal and bird livers are commonly eaten as food by humans. Liver can be baked, broiled, or fried (often served as liver and onions) or eaten raw (liver sashimi), but is perhaps most commonly made into spreads (examples include liver pâté, foie gras, chopped liver, and leverpostej), or sausages such as Braunschweiger and liverwurst). Liver sausages may also be used as spreads.
Animal livers are rich in iron and Vitamin A, and cod liver oil is commonly used as a dietary supplement. Very high doses of Vitamin A can be toxic; in 1913, Antarctic explorers Douglas Mawson and Xavier Mertz were both poisoned, the latter fatally, from eating husky liver. In the US, the USDA specifies 3000 μg per day as a tolerable upper limit, which amounts to about 50 g of raw pork liver, or 30-90g of polar-bear liver. However, acute vitamin A poisoning is not likely to result from liver consumption, since it is present in a less toxic form than in many dietary supplements.

Cultural allusions

In Greek mythology, Prometheus was punished by the gods for revealing fire to humans by being chained to a rock where a vulture (or an eagle) would peck out his liver, which would regenerate overnight. Curiously, the liver is the only human internal organ that actually can regenerate itself to a significant extent; this characteristic may have already been known to the Greeks due to survived injuries in battle.
The Talmud (tractate Berakhot 61b) refers to the liver as the seat of anger, with the gallbladder counteracting this.
In Arabic and Persian language, the liver is used in figurative speech to refer to courage and strong feelings, or "their best," e.g. "This Mecca has thrown to you the pieces of its liver!"
The legend of Liver-Eating Johnson says that he would cut out and eat the liver of each man killed.
In the motion picture The Message, Hind bint Utbah is implied or portrayed eating the liver of Hamza ibn ‘Abd al-Muttalib during the Battle of Uhud.
Inuit will not eat the liver of polar bears (due to the fact a polar bear's liver contains so much Vitamin A as to be poisonous to humans) or seals

Further reading

The following are standard medical textbooks:
  • Eugene R. Schiff, Michael F. Sorrell, Willis C. Maddrey, eds. Schiff's diseases of the liver, 9th ed. Philadelphia : Lippincott, Williams & Wilkins, 2003. ISBN 0-7817-3007-4
  • Sheila Sherlock, James Dooley. Diseases of the liver and biliary system, 11th ed. Oxford, UK ; Malden, MA : Blackwell Science. 2002. ISBN 0-632-05582-0
  • David Zakim, Thomas D. Boyer. eds. Hepatology: a textbook of liver disease, 4th ed. Philadelphia: Saunders. 2003. ISBN 0-7216-9051-3
These are for the lay reader or patient:
  • Sanjiv Chopra. The Liver Book: A Comprehensive Guide to Diagnosis, Treatment, and Recovery, Atria, 2002, ISBN 0-7434-0585-4
  • Melissa Palmer. Dr. Melissa Palmer's Guide to Hepatitis and Liver Disease: What You Need to Know, Avery Publishing Group; Revised edition May 24, 2004, ISBN 1-58333-188-3. her webpage.
  • Howard J. Worman. The Liver Disorders Sourcebook, McGraw-Hill, 1999, ISBN 0-7373-0090-6. his Columbia University web site, "Diseases of the liver"

References

Gallery

Image:Digestive system showing bile duct.png|Accessory digestive system. Image:BauchOrgane wn.png|Digestive organs. Image:Portal triad.JPG|Portal triad "top") surface from Gray's Anatomy (1918) "bottom") surface from Gray's Anatomy (1918)
liver in Arabic: كبد
liver in Aymara: K'iwcha
liver in Min Nan: Koaⁿ
liver in Bosnian: Jetra
liver in Bulgarian: Черен дроб
liver in Catalan: Fetge
liver in Chuvash: Пĕвер
liver in Czech: Játra
liver in Welsh: Afu
liver in Danish: Lever
liver in German: Leber
liver in Dhivehi: ފުރަމޭ
liver in Estonian: Maks
liver in Modern Greek (1453-): Ήπαρ
liver in Spanish: Hígado
liver in Esperanto: Hepato
liver in Basque: Gibel
liver in French: Foie
liver in Irish: Ae
liver in Scottish Gaelic: Àdha
liver in Galician: Fígado
liver in Korean: 간
liver in Hindi: कलेजा
liver in Croatian: Jetra
liver in Ido: Hepato
liver in Indonesian: Hati
liver in Icelandic: Lifur
liver in Italian: Fegato
liver in Hebrew: כבד
liver in Javanese: Ati
liver in Georgian: ღვიძლი
liver in Kurdish: Kezeb
liver in Latin: Iecur
liver in Latvian: Aknas
liver in Lithuanian: Kepenys
liver in Lingala: Libale
liver in Lombard: Fídech
liver in Hungarian: Máj
liver in Macedonian: Црн дроб
liver in Malayalam: കരള്‍
liver in Maltese: Fwied
liver in Malay (macrolanguage): Hati
nah:Ēltapachtli
liver in Dutch: Lever
liver in Japanese: 肝臓
liver in Norwegian: Leveren
liver in Norwegian Nynorsk: Lever
liver in Occitan (post 1500): Fetge
liver in Pangasinan: Altey
liver in Polish: Wątroba
liver in Portuguese: Fígado
liver in Romanian: Ficat
liver in Quechua: Kukupin
liver in Russian: Печень
liver in Albanian: Mëlçia
liver in Sicilian: Fìcatu
liver in Simple English: Liver
liver in Slovak: Pečeň
liver in Slovenian: Jetra
liver in Serbian: Јетра
liver in Serbo-Croatian: Jetra
liver in Sundanese: Ati
liver in Finnish: Maksa
liver in Swedish: Lever
liver in Tamil: கல்லீரல்
liver in Telugu: కాలేయం
liver in Thai: ตับ
liver in Vietnamese: Gan
liver in Tajik: Ҷигар
liver in Turkish: Karaciğer
liver in Ukrainian: Печінка
liver in Yiddish: לעבער
liver in Dimli: Kezebe
liver in Chinese: 肝臟

Synonyms, Antonyms and Related Words

abatis, abdomen, absorption, anus, appendix, assimilation, bile, blind gut, bowels, brain, brains, cecum, chitterlings, cholangitis, cholecystitis, cirrhosis, cockscomb, colon, denizen, digestion, digestive system, duodenum, dweller, endocardium, entrails, foregut, gastric juice, gastrointestinal tract, giblets, gizzard, guts, haslet, heart, hepatitis, hepatoma, hindgut, icterus, infectious hepatitis, ingestion, innards, inner mechanism, insides, internals, intestinal juice, intestine, inwards, jaundice, jejunum, kidney, kidneys, kishkes, large intestine, liver and lights, lung, marrow, midgut, occupant, pancreas, pancreatic digestion, pancreatic juice, perineum, predigestion, pump, pylorus, rectum, resident, resider, saliva, salivary digestion, salivary glands, secondary digestion, serum hepatitis, small intestine, spleen, stomach, sweetbread, ticker, tongue, tripe, tripes, vermiform appendix, viscera, vitals, works
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