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'{{other uses}} {{Infobox Anatomy | Name = Liver | Latin = Jecur, iecer ([[Greek language|Greek]]: Hepar) | GraySubject = 250 | GrayPage = 1188 | Image = Leber Schaf.jpg | Caption = Liver of a [[sheep]]: (1) right lobe, (2) left lobe, (3) [[caudate lobe]], (4) quadrate lobe, (5) hepatic artery and portal vein, (6) [[hepatic lymph nodes]], (7) [[gall bladder]]. | Image2 = Surface projections of the organs of the trunk.png | Caption2 = Surface projections of the organs of the [[Torso|trunk]], showing liver in center | Width = 240 | Precursor = [[foregut]] | System = |digestive system Artery = [[Hepatic artery proper|hepatic artery]] | Vein = [[hepatic vein]], [[hepatic portal vein]] | Nerve = [[celiac ganglia]], [[vagus]]<ref>{{GeorgiaPhysiology|6/6ch2/s6ch2_30}}</ref> | Lymph = | MeshName = Liver | MeshNumber = A03.620 | DorlandsPre = | DorlandsSuf = | }} The '''liver''', ''hepar'', is a [[vital organ]] present in [[vertebrate]]s and some other animals. It has a wide range of functions, including [[detoxification]], [[protein synthesis]], and production of biochemicals necessary for [[digestion]]. The liver is necessary for survival; there is currently no way to compensate for the absence of liver function in the long term, although new [[liver dialysis]] techniques can be used in the short term. This [[Organ (anatomy)|organ]] 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, [[hormone]] production, and detoxification. It lies below the diaphragm in the abdominal-pelvic region of the abdomen. It produces [[bile]], an alkaline compound which aids in [[digestion]] via the [[emulsification]] of [[lipids]]. The liver's highly specialized [[biological tissue|tissues]] regulate a wide variety of high-volume biochemical reactions, including the synthesis and breakdown of small and complex molecules, many of which are necessary for normal vital functions.<ref>{{cite book | last = Maton | first = Anthea | authorlink = | coauthors = Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright | title = Human Biology and Health | publisher = Prentice Hall | year = 1993 | location = Englewood Cliffs, New Jersey, USA | isbn = 0-13-981176-1 | oclc = 32308337}}</ref> Medical terms related to the liver often start in ''hepato-'' or ''hepatic'' from the [[Greek language|Greek]] word for liver, ''hēpar'' (ἡπαρ). ==Anatomy== The liver is a reddish brown organ with four [[Lobe (anatomy)|lobes]] of unequal size and shape. A human liver normally weighs {{convert|1.44|-|1.66|kg|lb|abbr=on}},<ref name="robbins">{{cite book |author=Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. |title=Robbins and Cotran pathologic basis of disease |publisher=Elsevier Saunders |location=St. Louis, MO |year=2005 |page=878 |isbn=0-7216-0187-1 |edition=7th }}</ref> and is a soft, pinkish-brown, triangular organ. It is both the largest internal organ (the [[skin]] being the largest organ overall) and the largest [[gland]] in the human body. It is located in the [[right upper quadrant]] of the [[abdominal cavity]], resting just below the [[Thoracic diaphragm|diaphragm]]. The liver lies to the right of the stomach and overlies the [[gallbladder]]. It is connected to two large [[blood vessel]]s, one called the hepatic artery and one called the [[portal vein]]. The [[hepatic artery]] carries blood from the aorta, whereas the portal vein carries blood containing digested nutrients from the entire [[gastrointestinal tract]] and also from the [[spleen]] and [[pancreas]]. These blood vessels subdivide into capillaries, which then lead to a lobule. Each lobule is made up of millions of hepatic cells which are the basic metabolic cells. [[Lobules of liver|Lobules]] are the functional units of the liver. ===Cell types=== Two major types of cells populate the liver lobes: karat parenchymal and non-parenchymal cells. 80% of the liver volume is occupied by parenchymal cells commonly referred to as [[hepatocytes]]. Non-parenchymal cells constitute 40% of the total number of liver cells but only 6.5% of its volume. Sinusoidal endothelial cells, [[Kupffer cells]] and hepatic stellate cells are some of the non-parenchymal cells that line the hepatic sinusoid.<ref>{{cite journal |author=Kmieć Z |title=Cooperation of liver cells in health and disease |journal=Adv Anat Embryol Cell Biol |volume=161 |issue= |pages=III–XIII, 1–151 |year=2001 |pmid=11729749 |doi=}}</ref> ===Blood flow=== The liver gets a dual blood supply from the [[hepatic portal vein]] and [[hepatic artery (disambiguation)|hepatic arteries]]. Supplying approximately 75% of the liver's blood supply, the hepatic portal vein carries [[venous blood]] drained from the [[spleen]], [[gastrointestinal tract]], and its associated organs. The hepatic arteries supply [[blood|arterial blood]] to the liver, accounting for the remainder of its [[blood flow]]. Oxygen is provided from both sources; approximately half of the liver's oxygen demand is met by the hepatic portal vein, and half is met by the hepatic arteries.<ref name="isbn1-55009-364-9">{{cite book |author=Benjamin L. Shneider; Sherman, Philip M. |title=Pediatric Gastrointestinal Disease |publisher=PMPH-USA|location=Connecticut |year=2008 |pages=751 |isbn=1-55009-364-9 }}</ref><br> Blood flows through the [[liver sinusoid]]s and empties into the central vein of each lobule. The [[Central veins of liver|central veins]] coalesce into hepatic veins, which leave the liver. [[File:Axial CT anomalous hepatic veins.jpg|thumb|right|axial CT image showing anomalous hepatic veins coursing on the subcapsular anterior surface of the liver.<ref name="Sheporaitis">{{cite journal|author=Lori Sheporaitis; Patrick C. Freeney|title=Hepatic and Portal Surface Veins:A New Anatomic Variant Revealed During Abdominal CT|publisher=American Journal of Roengenology 1998;171:1559-1564}}</ref>]] [[File:Anterior MIP image of anomalous hepatic veins.jpg|thumb|right|Maximum intensity projection (MIP) CT image as viewed anteriorly showing the anomalous hepatic veins coursing on the anterior surface of the liver]] [[File:Lateral MIP CT of anomalous surface hepatic veins.jpg|thumb|right|Lateral MIP view in the same patient]] ===Biliary flow=== [[Image:Anatomy of liver and gall bladder.png|thumb|200px|The biliary tree]] The term ''[[biliary tree]]'' is derived from the arboreal branches of the bile ducts. The [[bile]] produced in the liver is collected in [[bile canaliculi]], which merge to form [[bile duct]]s. Within the liver, these ducts are called ''intrahepatic'' (within the liver) bile ducts, and once they exit the liver they are considered ''extrahepatic'' (outside the liver). The intrahepatic ducts eventually drain into the right and left [[hepatic duct]]s, which 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 either drains 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 second part of the duodenum together at the [[ampulla of Vater]]. ===Surface anatomy=== ====Peritoneal ligaments==== Apart from a patch where it connects to the [[diaphragm (anatomy)|diaphragm]] (the so-called "[[bare area]]"), the liver is covered entirely by [[visceral]] [[peritoneum]], a thin, double-layered [[Mesothelium|membrane]] that reduces [[friction]] against other organs. The [[peritoneum]] folds back on itself to form the [[falciform ligament]] and the [[right triangular ligament|right]] and [[left triangular ligament]]s. These "[[peritoneum|lits]]" are in no way related to the true [[ligament|anatomic ligaments]] in [[joints]], and have essentially no known functional importance, but they are easily recognizable surface landmarks. An exception to this is the falciform ligament, which attaches the liver to the posterior portion of the anterior body wall. ====Lobes==== Traditional [[gross anatomy]] divided the liver into four [[lobe (anatomy)|lobe]]s 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 is 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 the [[quadrate lobe]] (the more inferior). From behind, the lobes are divided up by the [[ligamentum venosum]] and [[Round ligament of liver|ligamentum teres]] (anything left of these is the left lobe). The [[Transverse fissure of liver|transverse fissure]] (or ''[[porta hepatis]]'') divides the [[Caudate lobe of liver|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, 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. ===Functional anatomy=== {| class="wikitable" cellpadding=3 cellspacing=0 border=1 style="border-collapse: collapse; float:right; margin-left: 10px; margin-bottom:10px" |+ Correspondence between anatomic lobes and Couinaud segments |- !bgcolor="#ffffff"| '''Segment*''' !bgcolor="#cccccc"| '''[[Couinaud]] segments''' |- |bgcolor="#eeeeee"| Caudate |align=center|1 |- |bgcolor="#eeeeee"| Lateral |align=center|2, 3 |- |bgcolor="#eeeeee"| Medial |align=center|4a, 4b |- |bgcolor="#eeeeee"| Right |align=center| 5, 6, 7, 8 |- |colspan="2"| <div style="font-size:smaller"> <nowiki>*</nowiki> or lobe, in the case of the caudate lobe <br/> Each number in the list corresponds to one in the table. 1. Caudate <br> 2. Superior subsegment of the lateral segment <br> 3. Inferior subsegment of the lateral segment <br> 4a. Superior subsegment of the medial segment <br> 4b. Inferior subsegment of the medial segment <br> 5. Inferior subsegment of the anterior segment <br> 6. Inferior subsegment of the posterior segment <br> 7. Superior subsegment of the posterior segment <br> 8. Superior subsegment of the anterior segment <br> </div> |} The central area where the [[common bile duct]], [[hepatic portal vein]], and [[hepatic artery proper]] enter is the [[hilum (anatomy)|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 functional lobes are separated by an imaginary plane (historically called '''Cantlie's line''') joining the gallbladder fossa to the inferior vena cava. The plane 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 (anatomy)|posterior]] segment by the right hepatic vein. The left lobe is divided into the [[medial]] and [[Anatomical terms of location#Directional terms|lateral]] segments by the left hepatic vein. The fissure for the [[Round ligament of liver|ligamentum teres]] also separates the medial and lateral segments. The medial segment is also called the [[quadrate lobe]]. In the widely used [[Claude Couinaud|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.<ref name="3d">{{cite web |url=http://dpi.radiology.uiowa.edu/nlm/app/livertoc/liver/liver.html |title=Three-dimensional Anatomy of the Couinaud Liver Segments |work= |accessdate=2009-02-17}}</ref><ref name="strunk">{{cite web |url=http://www.uni-bonn.de/~umm705/quiz0403.htm |title=Prof. Dr. Holger Strunk |accessdate=2009-02-17}}</ref> ===In other animals=== The liver is found in all [[vertebrate]]s, and is typically the largest [[viscera]]l organ. Its form varies considerably in different species, and is largely determined by the shape and arrangement of the surrounding organs. Nonetheless, in most species it is divided into right and left lobes; exceptions to this general rule include [[snake]]s, where the shape of the body necessitates a simple cigar-like form. The internal structure of the liver is broadly similar in all vertebrates.<ref name=VB>{{cite book |author=Romer, Alfred Sherwood|author2=Parsons, Thomas S.|year=1977 |title=The Vertebrate Body |publisher=Holt-Saunders International |location= Philadelphia, PA|pages= 354–5 |isbn= 0-03-910284-X}}</ref> An organ sometimes referred to as a liver is found associated with the digestive tract of the primitive chordate ''[[Amphioxus]]''. However, this is an enzyme secreting gland, not a metabolic organ, and it is unclear how truly [[homology (biology)|homologous]] it is to the vertebrate liver.<ref name=VB/> ==Physiology== The various functions of the liver are carried out by the liver cells or [[hepatocyte]]s. 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]]. The liver is thought to be responsible for up to 500 separate functions, usually in combination with other systems and organs. ===Synthesis=== {{Further|Proteins produced and secreted by the liver}} [[File:CTscanofmyLiver.jpg|thumb|A CT scan in which the liver and portal vein are shown.]] * A large part of [[amino acid synthesis]] * The liver performs several roles in [[carbohydrate metabolism]]: ** ''[[Gluconeogenesis]]'' (the synthesis of [[glucose]] from certain [[amino acid]]s, [[lactic acid|lactate]] or [[glycerol]]) ** ''[[Glycogenolysis]]'' (the breakdown of [[glycogen]] into [[glucose]]) ** ''[[Glycogenesis]]'' (the formation of glycogen from glucose)(muscle tissues can also do this) * The liver is responsible for the mainstay of protein [[metabolism]], synthesis as well as degradation. * The liver also performs several roles in [[lipid]] metabolism: ** ''[[Cholesterol]] synthesis'' ** ''[[Lipogenesis]]'', the production of [[triglyceride]]s (fats). ** A bulk of the lipoproteins are synthesized in the liver. * The liver produces [[coagulation factors]] [[fibrinogen|I]] (fibrinogen), [[thrombin|II]] (prothrombin), [[factor V|V]], [[factor VII|VII]], [[factor IX|IX]], [[factor X|X]] and [[factor XI|XI]], as well as [[protein C]], [[protein S]] and [[antithrombin]]. * In the first trimester [[fetus]], the liver is the main site of [[red blood cell]] production. By the 32nd week of [[gestation]], the [[bone marrow]] has almost completely taken over that task. * The liver produces and excretes [[bile]] (a yellowish liquid) required for emulsifying fats and help the absorption of vitamin K from the diet. Some of the bile drains directly into the [[duodenum]], and some is stored in the [[gallbladder]]. * The liver also produces [[insulin-like growth factor 1]] (IGF-1), a [[polypeptide]] [[protein]] hormone that plays an important role in childhood growth and continues to have [[anabolism|anabolic effects]] in adults. * The liver is a major site of [[thrombopoietin]] production. Thrombopoietin is a [[glycoprotein]] hormone that regulates the production of [[platelet]]s by the [[bone marrow]]. ===Breakdown=== * The breakdown of [[insulin]] and other [[hormone]]s * The liver [[glucuronidation|glucoronidates]] [[bilirubin]], facilitating its excretion into [[bile]]. * The liver breaks down or modifies [[toxic]] substances (e.g., methylation) and most medicinal products in a process called [[drug metabolism]]. This sometimes results in [[toxication]], when the metabolite is more toxic than its precursor. Preferably, the toxins are [[Xenobiotic conjugation|conjugated]] to avail excretion in bile or urine. * The liver converts [[ammonia]] to [[urea]] ([[urea cycle]]). ===Other functions=== * The liver stores a multitude of substances, including glucose (in the form of [[glycogen]]), [[vitamin A]] (1–2 years' supply), [[vitamin D]] (1–4 months' supply){{Citation needed|date=September 2012}}, [[vitamin B12]] (1–3 years' supply), [[vitamin K]], [[iron]], and [[copper]]. * The liver is responsible for immunological effects—the [[reticuloendothelial system]] of the liver contains many immunologically active cells, acting as a 'sieve' for antigens carried to it via the [[Hepatic portal system|portal system]]. * The liver produces [[albumin]], the major [[osmolar]] component of [[Blood plasma|blood serum]]. * The liver synthesizes [[angiotensinogen]], a hormone that is responsible for raising the [[blood pressure]] when activated by [[renin]], an enzyme that is released when the [[juxtaglomerular apparatus|kidney]] senses [[Hypotension|low blood pressure]]. SHIT SHIT SHIT SHIT SHIT SHIT SHIT FUCK FUCK FUCK FUCK FUCK BALLS BALLS BALLS BALLS TITS TITS TITS TITS ===Relation to medicine and pharmacology=== The oxidative capacity of the liver decreases with aging and therefore, [[benzodiazepines]] (BZDs) that require oxidation are more likely to accumulate to toxic levels. Therefore, those with shorter half-lives, such as [[lorazepam]] and [[oxazepam]] are preferred when benzodiazepines are required in regards to [[geriatric medicine]]. ==Diseases of the liver== <!-- This section is linked from [[George Mason University]] --> {{Main|Liver disease}} [[File:Big Liver Tumor.JPG|right|thumb| Left lobe liver tumor]] The liver supports almost every organ in the body and is vital for survival. Because of its strategic location and multidimensional functions, the liver is also prone to many diseases.<ref>[http://digestive.niddk.nih.gov/ddiseases/pubs/cirrhosis/ Cirrhosis Overview] National Digestive Diseases Information Clearinghouse. Retrieved on 2010-01-22</ref> The most common include: Infections such as [[Viral hepatitis|hepatitis A, B, C, D, E]], [[alcoholic beverage|alcohol]] damage, [[fatty liver]], [[cirrhosis]], [[cancer]], drug damage (particularly by [[paracetamol|acetaminophen]] (paracetamol) and cancer drugs). 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 [[Haemoglobin|hemoglobin]] of dead [[red blood cell]]s; normally, the liver removes bilirubin from the blood and excretes it through bile. There are also many pediatric liver diseases including [[biliary atresia]], [[alpha-1 antitrypsin deficiency]], [[alagille syndrome]], [[progressive familial intrahepatic cholestasis]], and [[Langerhans cell]] histiocytosis, to name but a few. Diseases that interfere with liver function will lead to derangement of these processes. However, the liver has a great capacity to [[regeneration (biology)|regenerate]] and has a large reserve capacity. In most cases, the liver only produces symptoms after extensive damage. Liver diseases may be diagnosed by [[liver function tests]], for example, by production of [[acute phase protein]]s. ==Disease symptoms== The classic symptoms of liver damage include the following: * '''Pale stools''' occur when [[stercobilin]], a brown pigment, is absent from the stool. Stercobilin is derived from bilirubin metabolites produced in the liver. * '''Dark urine''' occurs when bilirubin mixes with urine * '''Jaundice''' (yellow skin and/or whites of the eyes) This is where [[bilirubin]] deposits in skin, causing an intense [[itch]]. Itching is the most common complaint by people who have liver failure. Often this itch cannot be relieved by drugs. * '''[[swelling (medical)|Swelling]]''' of the abdomen, ankles and feet occurs because the liver fails to make [[albumin]]. * '''Excessive fatigue''' occurs from a generalized loss of nutrients, [[dietary mineral|minerals]] and vitamins. * '''[[bruise|Bruising]]''' and easy bleeding are other features of liver disease. The liver makes substances which help prevent bleeding. When liver damage occurs, these substances are no longer present and severe bleeding can occur.<ref>[http://www.ccfa.org/info/about/complications/liver Extraintestinal Complications: Liver Disease] Crohn's & Colitis Foundation of America. Retrieved on 2010-01-22</ref> ==Diagnosis== The diagnosis of liver function is made by [[blood test]]s. Liver function tests can readily pinpoint the extent of liver damage. If [[infection]] is suspected, then other [[serology|serological]] tests are done. Sometimes, one may require an [[ultrasound]] or a [[X-ray computed tomography|CT scan]] to produce an image of the liver. Physical examination of the liver is not accurate in determining the extent of liver damage. It can only reveal presence of tenderness or the size of liver, but in all cases, some type of radiological study is required to examine it.<ref>[http://www.healthline.com/galecontent/liver Liver Information] HealthLine. Retrieved on 2010-01-22</ref> ==Biopsy / scan== Damage to the liver is sometimes determined with a [[biopsy]], particularly when the cause of liver damage is unknown. In the 21st century they were largely replaced by high-resolution radiographic scans. The latter do not require ultrasound guidance, lab involvement, microscopic analysis, organ damage, pain, or patient sedation; and the results are available immediately on a computer screen. In a biopsy, a needle is inserted into the skin just below the rib cage and a tissue sample obtained. The tissue is sent to the laboratory, where it is analyzed under a [[microscope]]. Sometimes, a radiologist may assist the physician performing a [[liver biopsy]] by providing ultrasound guidance.<ref>[http://www.medicinenet.com/script/main/art.asp?articlekey=191 Liver.. The largest gland in the body] MedicineNet. Retrieved on 2010-01-22</ref> ==Regeneration== The liver is the only internal human organ capable of natural [[regeneration (biology)|regeneration]] of lost [[Biological tissue|tissue]]; as little as 25% of a liver can regenerate into a whole liver.<ref name=regen>{{cite book|title=Liver Regeneration|year=2011|publisher=De Gruyter|location=Berlin|isbn=9783110250794|pages=214|url=http://books.google.co.za/books?id=RJEg-p-9iqsC&pg=PA1|editor=Dieter Häussinger|page=1}}</ref> This is, however, not true regeneration but rather [[Compensatory growth (organ)|compensatory growth]].<ref>{{cite book|title=Robbins and Cotran Pathologic Basis of Disease|year=1999|isbn=0-8089-2302-1|edition=7th|page=101}}</ref> The lobes that are removed do not regrow and the growth of the liver is a restoration of function, not original form. This contrasts with true regeneration where both original function and form are restored. This is predominantly due to the [[hepatocyte]]s re-entering the [[cell cycle]]. That is, the hepatocytes go from the quiescent [[G0 phase]] to the [[G1 phase]] and undergo mitosis. This process is activated by the [[p75]] receptors.<ref name="pmid18515089">{{cite journal |author=Suzuki K, Tanaka M, Watanabe N, Saito S, Nonaka H, Miyajima A |title=p75 Neurotrophin receptor is a marker for precursors of stellate cells and portal fibroblasts in mouse fetal liver |journal=Gastroenterology |volume=135 |issue=1 |pages=270–281.e3 |year=2008 |month=July |pmid=18515089 |doi=10.1053/j.gastro.2008.03.075 |url=http://linkinghub.elsevier.com/retrieve/pii/S0016-5085(08)00571-4}}</ref> There is also some evidence of [[bipotential]] [[stem cell]]s, called hepatic oval cells or ovalocytes (not to be confused with oval red blood cells of [[Southeast Asian ovalocytosis|ovalocytosis]]), which are thought to reside in the [[canals of Hering]]. These cells can differentiate into either [[hepatocyte]]s or [[cholangiocyte]]s, the latter being the cells that line the [[bile ducts]]. Scientific and medical works about liver regeneration often refer to the Greek [[Titan (mythology)|Titan]] [[Prometheus]] who was chained to a rock in the Caucasus where, each day, his liver was devoured by an eagle, only to grow back each night. Some think the myth indicates the [[Ancient Greece|ancient Greeks]] knew about the liver’s remarkable capacity for self-repair, though this claim has been challenged.<ref>An argument for the ancient Greek’s knowing about liver regeneration is provided by Chen T and Chen P (1994). [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1294986/= "The Myth of Prometheus and the Liver"]. Journal of the Royal Society of Medicine 87(12): 754-755. A counterargument is provided by Power C and Rasko J (2008). [http://www.annals.org/content/149/6/421.full.pdf+html?sid=b7f69a75-d6ef-4268-92f9-f6cd391f18da= "Whither Prometheus' Liver? Greek Myth and the Science of Regeneration"]. Annals of Internal Medicine 149(6): 421-426.</ref> ==Liver transplantation== {{Main|Liver transplantation}} Human liver transplants were first performed by [[Thomas Starzl]] in the [[United States]] and [[Roy Calne]] in [[Cambridge]], [[England]] in 1963 and 1965, respectively. [[File:Liver..JPG|right|thumb|After resection of left lobe liver tumor]] [[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 [[allograft]]s for [[organ transplantation|transplant]] usually come from donors who have died from fatal [[Traumatic brain injury|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 percent 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 percent of the liver. Due to the ability of the liver to [[regeneration (biology)|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 two 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.<ref>{{cite journal | author = Bramstedt K | title = Living liver donor mortality: where do we stand? | journal = Am. J. Gastrointestinal | volume = 101 | issue = 4 | pages = 755–9 | year = 2006 | pmid = 16494593 | doi = 10.1111/j.1572-0241.2006.00421.x}}</ref> The risk of postoperative complications (and death) is far greater in right-sided operations than that in left-sided operations. With the recent advances of noninvasive 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 multidetector 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 operations. <gallery> Image:LDLTA.jpg|MDCT image. Arterial anatomy contraindicated for liver donation Image:LDLTP.jpg|MDCT image. Portal venous anatomy contraindicated for liver donation Image:LDLT volume measure.jpg|MDCT image. 3D image created by MDCT can clearly visualize the liver, measure the liver volume, and plan the dissection plane to facilitate the liver transplantation procedure. Image:R_vs_L_Liver_by_CT.PNG|Phase contrast CT image. Contrast is perfusing the right liver but not the left due to a left portal vein thrombus. </gallery> ==Additional Images== <gallery> File:Slide1ppp.JPG|Liver File:Liver 5.jpg|Liver File:Liver 2.jpg|Liver File:Liver 3.jpg|Dissection of portal vein in right lobe of liver]] </gallery> ==Development== ===Organogenesis=== The origins of the liver lie in both the ventral portion of the [[foregut]] [[endoderm]] (endoderm being one of the 3 embryonic germ cell layers) and the constituents of the adjacent [[septum transversum]] [[mesenchyme]]. In human [[embryo]], the [[hepatic diverticulum]] is the tube of endoderm that extends out from the foregut into the surrounding mesenchyme. The mesenchyme of septum transversum induces this endoderm to proliferate, to branch, and to form the glandular epithelium of the liver. A portion of the hepatic diverticulum (that region closest to the digestive tube) continues to function as the [[Biliary tract|drainage duct]] of the liver, and a branch from this duct produces the [[gallbladder]].<ref>{{cite book | last = Gilbert SF | first = | authorlink = | coauthors = | title = Developmental Biology | edition=6th | publisher = Sinauer Associates | year = 2000 | location = Sunderland (MA) | isbn = | oclc = |url=http://www.ncbi.nlm.nih.gov/books/NBK10107/#A3752}}</ref> Besides of signals from the septum transversum mesenchyme, [[fibroblast growth factor]] from the [[Heart development|developing heart]] also contribute to hepatic competence, along with [[retinoic acid]] emanating from the [[lateral plate mesoderm]]. The hepatic endodermal cells undergo a morphological transition from columnar to pseudostratified resulting in thickening into the early [[Hepatic diverticulum|liver bud]]. Their expansion forms a population of the bipotential hepatoblasts.<ref name="pmid21337461">{{cite journal | author = Lade AG, Monga SP | title = Beta-catenin signaling in hepatic development and progenitors: which way does the WNT blow? | journal = Dev Dyn | volume = 240 | issue = 3 | pages = 486–500 | year = 2011 | pmid = 21337461 | doi = 10.1002/dvdy.22522}}</ref> [[Hepatic stellate cell]]s are derived from mesenchyme.<ref>{{cite journal | author = Berg T, DeLanghe S, Al Alam D, Utley S, Estrada J, Wang KS | title = β-catenin regulates mesenchymal progenitor cell differentiation during hepatogenesis | journal = J Surg Res | volume = 164| issue = 2 | pages = 276–85 | year = 2010 | pmid = 20381814 | doi = 10.1016/j.jss.2009.10.033}}</ref> After migration of hepatoblasts into the septum transversum mesenchyme, the hepatic architecture begins to be established, with sinusoids and bile canaliculi appearing. The liver bud separates into the lobes. The left [[umbilical vein]] becomes the [[ductus venosus]] and the right [[Vitelline veins|vitelline vein]] becomes the [[portal vein]]. The expanding liver bud is colonized by [[Hematopoietic stem cell|hematopoietic cells]]. The bipotential hepatoblasts begin differentiating into [[Cholangiocyte|biliary epithelial cells]] and [[hepatocyte]]s. The biliary epithelial cells differentiate from hepatoblasts around portal veins, first producing a monolayer, and then a bilayer of cuboidal cells. In ductal plate, focal dilations emerge at points in the bilayer, become surrounded by portal mesenchyme, and undergo tubulogenesis into intrahepatic bile ducts. Hepatoblasts not adjacent to portal veins instead differentiate into hepatocytes and arrange into cords lined by sinudoidal epithelial cells and bile canaliculi. Once hepatoblasts are specified into hepatocytes and undergo further expansion, they begin acquiring the functions of a mature hepatocyte, and eventually mature hepatocytes appear as highly polarized epithelial cells with abundant [[glycogen]] accumulation. In the adult liver, hepatocytes are not equivalent, with position along the portocentrovenular axis within a [[Lobules of liver|liver lobule]] dictating expression of metabolic genes involved in drug metabolism, carbohydrate metabolism, ammonia detoxification, and bile production and secretion. [[Wnt signaling pathway|WNT/β-catenin]] has now been identified to be playing a key role in this phenomenon.<ref name="pmid21337461"/> ===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 in two to five days; the former becomes the [[Round ligament of liver|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. ==As food== {{main|Liver (food)}} ==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. (The liver is the only human internal organ that actually can regenerate itself to a significant extent.) Many ancient peoples of the Near East and Mediterranean areas practiced a type of [[divination]] called [[haruspicy]], where they tried to obtain information by examining the livers of sheep and other animals. In Plato, and in later physiology, the liver was thought to be the seat of the darkest emotions (specifically wrath, jealousy and greed) which drive men to action.<ref>{{cite book |title= Kundalini – the evolutionary energy in man |last= Krishna |first= Gopi |authorlink= Gopi Krishna |coauthors= [[James Hillman|Hillman, James]] (commentary)|year= 1970 |publisher= Stuart & Watkins |location= London |id= SBN 7224 0115 9 |pages= 77 |url= http://www.scribd.com/doc/7577310/KUNDALINI-the-evolutionary-energy-in-man }}</ref> The [[Talmud]] (tractate ''Berakhot 61b'') refers to the liver as the seat of [[anger]], with the [[gallbladder]] counteracting this. The [[Persian language|Persian]], [[Urdu]], and [[Hindi]] languages (جگر or जिगर or ''jigar'') refer to the liver in figurative speech to indicate courage and strong feelings, or "their best"; e.g., "This [[Mecca]] has thrown to you the pieces of its liver!".<ref>[http://www.shawuniversitymosque.org/m/faq_qanda.php?id=94 THE GREAT BATTLE OF BADAR (Yaum-e-Furqan)]</ref> The term ''jan e jigar'', literally "the strength (power) of my liver", is a term of endearment in Urdu. In Persian slang, ''jigar'' is used as an adjective for any object which is desirable, especially women. In the [[Zulu language]], the word for liver (isibindi) is the same as the word for courage. The legend of [[Liver-Eating Johnson]] says that he would cut out and eat the liver of each man killed after dinner. In the motion picture ''[[Mohammad, Messenger of God (film)|The Message]]'', [[Hind bint Utbah]] is implied or portrayed eating the liver of [[Hamza ibn ‘Abd al-Muttalib]] during the [[Battle of Uhud]]. Although there are narrations that suggest that Hind did "taste", rather than eat, the liver of Hamza, the authenticity of these narrations have to be questioned. == See also == * [[Artificial liver]] * [[Bile]] * [[Bile canaliculus]] * [[Hepatic cyst]] (liver cyst) * [[Hepatocyte]] * [[Liver function tests]] * [[Liver shot|Liver shot (martial arts strike)]] * [[Polycystic liver disease]] * [[Anastomosis|Porto-Systemic anastomosis]] ==References== {{reflist|2}} ==External links== {{Wiktionary|liver}} {{Commons category|Livers}} *[http://search.dmoz.org/cgi-bin/search?search=liver Liver] at the [[Dmoz|Open Directory Project]]. *[http://pie.med.utoronto.ca/VLiver/ VIRTUAL Liver - online learning resource] *[http://liverenzymes.net Liver enzymes] {{Animal anatomy}} {{Digestive glands}} [[Category:Liver| ]] [[Category:Organs]] {{Link GA|cs}} [[af:Lewer]] [[am:ጉበት]] [[ang:Lifere]] [[ar:كبد]] [[an:Figado]] [[arc:ܟܒܕܐ]] [[ast:Fégadu]] [[av:ТӀул]] [[ay:K'iwcha]] [[az:Qaraciyər]] [[bn:যকৃৎ]] [[zh-min-nan:Koaⁿ]] [[be:Печань]] [[be-x-old:Печань]] [[bg:Черен дроб]] [[bs:Jetra]] [[br:Avu]] [[ca:Fetge]] [[cv:Пĕвер]] [[cs:Játra]] [[sn:Chitaka]] [[cy:Afu]] [[da:Lever]] [[de:Leber]] [[dv:ފުރަމޭ]] [[et:Maks]] [[el:Ήπαρ]] [[es:Hígado]] [[eo:Hepato]] [[eu:Gibel]] [[fa:کبد]] [[fr:Foie]] [[ga:Ae]] [[gd:Àdha]] [[gl:Fígado]] [[hak:Kôn-tshóng]] [[ko:간]] [[hy:Լյարդ]] [[hi:यकृत]] [[hr:Jetra]] [[io:Hepato]] [[id:Hati]] [[is:Lifur]] [[it:Fegato]] [[he:כבד]] [[jv:Ati]] [[kn:ಯಕೃತ್ತು]] [[pam:Ate]] [[ka:ღვიძლი]] [[kk:Бауыр (орган)]] [[sw:Ini]] [[ht:Fwa]] [[ku:Kezeb]] [[lbe:ТтиликӀ]] [[la:Iecur]] [[lv:Aknas]] [[lt:Kepenys]] [[ln:Libale]] [[lez:Лекь (анатомия)]] [[lmo:Fídech]] [[hu:Máj]] [[mk:Црн дроб]] [[ml:കരൾ]] [[mt:Fwied]] [[mr:यकृत]] [[ms:Hati]] [[mn:Элэг]] [[my:အသည်း]] [[nah:Ēltapachtli]] [[nl:Lever]] [[new:सें]] [[ja:肝臓]] [[no:Lever]] [[nn:Lever]] [[oc:Fetge]] [[mhr:Мокш]] [[or:ଯକୃତ]] [[om:Tiruu]] [[pag:Altey]] [[pnb:کلیجہ]] [[ps:اينه]] [[nds:Lebber]] [[pl:Wątroba]] [[pt:Fígado]] [[ro:Ficat]] [[qu:Kukupin]] [[rue:Печунка]] [[ru:Печень]] [[sah:Быар]] [[sa:यकृत्]] [[sq:Mëlçia]] [[scn:Fìcatu]] [[simple:Liver]] [[sk:Pečeň]] [[sl:Jetra]] [[so:Beer (xubin)]] [[ckb:جەرگ]] [[sr:Јетра]] [[sh:Jetra]] [[su:Ati]] [[fi:Maksa]] [[sv:Lever]] [[tl:Atay]] [[ta:கல்லீரல்]] [[te:కాలేయం]] [[th:ตับ]] [[tg:Ҷигар]] [[tr:Karaciğer]] [[tk:Bagyr]] [[uk:Печінка]] [[ur:جگر]] [[ug:جىگەر]] [[za:Daep]] [[vec:Figà]] [[vi:Gan]] [[wa:Foete]] [[war:Atay]] [[yi:לעבער]] [[zh-yue:肝]] [[diq:Kezebe]] [[zh:肝臟]]'