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Liver
Leber Schaf.jpg
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.
Gray1224.png
Anterior view of the position of the liver (red) in the human abdomen.
Latin jecur, iecer
Gray's subject #250 1188
Vein hepatic vein, hepatic portal vein
Nerve celiac ganglia, vagus[1]
Precursor foregut
MeSH Liver

The liver is a vital organ present in vertebrates 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.

This 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 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 highly specialized tissues, including the synthesis and breakdown of small and complex molecules, many of which are necessary for normal vital functions.[2]

Medical terms related to the liver often start in hepato- or hepatic from the Greek word for liver, hēpar (ἡπαρ).[3]

Contents

Structural overview

The liver is the largest glandular organ with a weight of about 1.5 kg (3.3 lb). It is a reddish brown organ with four lobes of unequal size and shape. The liver is on the right side of the abdominal cavity just below the diaphragm and is connected to two large blood vessels, 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 small intestine and the descending colon. These blood vessels subdivide into capillaries which then lead to a lobule. Each lobule is made up of thousands of hepatic cells which are the basic metabolic cells.

Anatomy

An adult human liver normally weighs between 1.4–1.6 kg (3.1–3.5 lb),[4] 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 diaphragm. The liver lies to the right of the stomach and overlies the gallbladder.

Blood flow

The liver receives a dual blood supply from the hepatic portal vein and 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 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.[5]
Blood flows through the sinusoids and empties into the central vein of each lobule. The central veins coalesce into hepatic veins, which leave the liver and empty into the inferior vena cava.

Biliary flow

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 ducts. 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 ducts, 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 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 second part of the duodenum together at the ampulla of Vater.

The biliary tree

Surface anatomy

Peritoneal ligaments

Apart from a patch where it connects to the diaphragm (the so-called "bare area"), 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 "lits" 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. 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 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.

Functional anatomy

Correspondence between anatomic lobes and Couinaud segments
Segment* Couinaud segments
Caudate 1
Lateral 2, 3
Medial 4a, 4b
Right 5, 6, 7, 8

* or lobe in the case of the caudate lobe.
Each number in the list corresponds to one in the table.

  1. Caudate
  2. Superior subsegment of the lateral segment
  3. Inferior subsegment of the lateral segment
    1. Superior subsegment of the medial segment
    2. Inferior subsegment of the medial segment
  4. Inferior subsegment of the anterior segment
  5. Inferior subsegment of the posterior segment
  6. Superior subsegment of the posterior segment
  7. Superior subsegment of the anterior segment

The central area where the common bile duct, hepatic portal vein, and hepatic artery proper 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 functional lobes are separated by an imaginary plane 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 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 also separates the medial and lateral segments. The medial segment is also 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.[6][7]

In other animals

The liver is found in all vertebrates, and is typically the largest visceral 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 snakes, where the shape of the body necessitates a simple cigar-like form. The internal structure of the liver is broadly similar in all vertebrates.[8]

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 homologous it is to the vertebrate liver.[8]

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.

Synthesis

Breakdown

Other functions

Diseases of the liver

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. [9]

The most common include : Infections such as hepatitis A, B, C, E, alcohol damage, fatty liver, cirrhosis, cancer, drug damage (especially acetaminophen, 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 of dead red blood cells; 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 regenerate and has a large reserve capacity. In most cases, the liver only produces symptoms after extensive damage. [10]

Liver diseases may be diagnosed by liver function tests, for example, by production of acute phase proteins.

Disease signs

The classic signs 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
  • Bilirubin when it deposits in skin, causes an intense itch. Itching is the most common complaint by people who have liver failure. Often this itch cannot be relieved by drugs.
  • Swelling of the abdomen, ankles and feet occurs because the liver fails to make albumin.
  • Excessive fatigue occurs from a generalized loss of nutrients, minerals and vitamins.
  • 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. [11]

Diagnosis

The diagnosis of liver function is made by blood tests. Liver function tests can readily pinpoint the extent of liver damage. If infection is suspected, then other serological tests are done. Sometimes one may require an ultrasound or a CT scan to image the liver.

Physical exam of the liver is not accurate in determining the extent of liver damage. Physical exam can only reveal presence of tenderness or size of liver but in all cases some type of radiological study is required to look at the liver [12]

Biopsy

The ideal way to look at damage to the liver is with a biopsy. A biopsy is not required in all cases but may be necessary when the cause is unknown. The procedure is done at the bedside and only requires local anesthetic. A small thin needle is inserted into the skin just below the rib cage and a biopsy is obtained. The tissue is sent to the laboratory where it is analyzed under a microscope. Sometimes the radiologist may perform a liver biopsy under ultrasound guidance if only a small area is involved. [13]

Regeneration

The liver is the only internal human organ capable of natural regeneration of lost tissue; as little as 25% of a liver can regenerate into a whole liver. A human liver is known to grow back in as little as a week to no more than a few weeks, due to hyptochronatin cells in the remaining liver.[14]

This is predominantly due to the hepatocytes 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.[15] There is also some evidence of bipotential stem cells, called ovalocytes or hepatic oval cells, which are thought to reside in the canals of Hering. These cells can differentiate into either hepatocytes or cholangiocytes, the latter being the cells that line the bile ducts.

The capability for the liver to regenerate itself has been known since at least the times of the ancient Greeks, whose mythology includes a story about Prometheus being chained to a rock in the Caucasus mountain and his liver being partially eaten during the day by an eagle only to "regenerate" in the night.[16] The story, however, embellishes the speed with which this occurs.

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.

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 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.[17] 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 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 operations.

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 in two to five days; 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.

As food

Cultural allusions

The liver has always been an important symbol in occult physiology. As the largest organ, the one containing the most blood, it was regarded as the darkest, least penetrable part of man's innards. Thus it was considered to contain the secret of fate and was used for fortune-telling. In Plato, and in later physiology, the liver represented the darkest passions, particularly the bloody, smoky ones of wrath, jealousy, and greed which drive men to action. Thus the liver meant the impulsive attachment to life itself.

James Hillman[18]

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 practised a type of divination called haruspicy, whereby they tried to obtain information from examining the livers of sheep and other animals.

The Talmud (tractate Berakhot 61b) refers to the liver as the seat of anger, with the gallbladder counteracting this.

The 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!" [19]. 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 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

References

  1. ^ Physiology at MCG 6/6ch2/s6ch2_30
  2. ^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1. OCLC 32308337. 
  3. ^ The Greek word "ἡπαρ" was derived from hēpaomai (ηπάομαι): to mend, to repair, hence hēpar actually means "repairable", indicating that this organ can regenerate itself spontaneously in the case of lesion.
  4. ^ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease. St. Louis, MO: Elsevier Saunders. pp. 878. ISBN 0-7216-0187-1. 
  5. ^ Benjamin L. Shneider; Sherman, Philip M. (2008). Pediatric Gastrointestinal Disease. Connecticut: PMPH-USA. pp. 751. ISBN 1-55009-364-9. 
  6. ^ "Three-dimensional Anatomy of the Couinaud Liver Segments". http://dpi.radiology.uiowa.edu/nlm/app/livertoc/liver/liver.html. Retrieved 2009-02-17. 
  7. ^ "Prof. Dr. Holger Strunk - Homepage". http://www.uni-bonn.de/~umm705/quiz0403.htm. Retrieved 2009-02-17. 
  8. ^ a b Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 354-355. ISBN 0-03-910284-X. 
  9. ^ Cirrhosis Overview National Digestive Diseases Information Clearinghouse. Retrieved on 2010-01-22
  10. ^ Liver Tissue Damage And Treatment Retrieved on 2010-01-22
  11. ^ Extraintestinal Complications: Liver Disease Crohn's & Colitis Foundation of America. Retrieved on 2010-01-22
  12. ^ Liver Information HealthLine. Retrieved on 2010-01-22
  13. ^ Liver.. The largest gland in the body MedicineNet. Retrieved on 2010-01-22
  14. ^ Liver Regeneration May Be Simpler Than Previously Thought, April 2007, http://www.medicalnewstoday.com/articles/67653.php 
  15. ^ Suzuki K, Tanaka M, Watanabe N, Saito S, Nonaka H, Miyajima A (July 2008). "p75 Neurotrophin receptor is a marker for precursors of stellate cells and portal fibroblasts in mouse fetal liver". Gastroenterology 135 (1): 270–281.e3. doi:10.1053/j.gastro.2008.03.075. PMID 18515089. http://linkinghub.elsevier.com/retrieve/pii/S0016-5085(08)00571-4. 
  16. ^ Michalopoulos, George K., and DeFrances, Marie C., "Liver regeneration:, Science, 4 April 1997: Vol. 276. no. 5309, pp. 60 - 66: "The ancient Greeks recognized liver regeneration in the myth of Prometheus. Having stolen the secret of fire from the gods of Olympus, Prometheus was condemned to having a portion of his liver eaten daily by an eagle. His liver regenerated overnight,"
  17. ^ Bramstedt K (2006). "Living liver donor mortality: where do we stand?". Am. J. Gastrointestinal 101 (4): 755–9. doi:10.1111/j.1572-0241.2006.00421.x. PMID 16494593. 
  18. ^ Krishna, Gopi; Hillman, James (commentary) (1970). Kundalini – the evolutionary energy in man. London: Stuart & Watkins. pp. 77. SBN 7224 0115 9. http://www.scribd.com/doc/7577310/KUNDALINI-the-evolutionary-energy-in-man. 
  19. ^ THE GREAT BATTLE OF BADAR (Yaum-e-Furqan)

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"

External links


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

LIVER (0. Eng. lifer; cf. cognate forms, Dutch lever, Ger. Leber, Swed. lefver, &c.; the O. H. Ger. forms are libara, lipora, &c.; the Teut. word has been connected with Gr.: 7,7rap and Lat. jecur), in anatomy, a large reddish-brown digestive gland situated in the upper and right part of the abdominal cavity. When hardened in situ its shape is that of a right-angled, triangular prism showing five surfaces - superior, anterior, inferior, posterior and right lateral which represents the base of the prism. It weighs about three pounds or one-fortieth of the body weight.

Although the liver is a fairly solid organ, it is plastic, and moulds itself to even hollow neighbouring viscera rather than they to it. The superior surface is in contact with the diaphragm, but has peritoneum between (see Coelom And Serous Membranes). At its posterior margin the peritoneum of the great sac is reflected on to the diaphragm to form the anterior layer of the coronary ligament. Near the mid line of the body, and at right angles to the last, another reflection, the falciform ligament, runs forward, and the line of attachment of this indicates the junction of the right and left lobes of the liver. The anterior surface is in contact with the diaphragm and the anterior abdominal wall. The attachment of the falciform ligament is continued down it. The posterior surface is more complicated (see fig. I); starting from the right and working toward the left, a large triangular area, uncovered by peritoneum and in direct contact with the diaphragm, is seen. This is bounded on the left by the inferior vena cava, which is sunk into a deep groove in the liver, and into the upper part of this the hepatic veins open. Just to the right of this and at the lower part of the bare area is a triangular depression for the right suprarenal body. To the left of the vena cava is the Spigelian lobe, which lies in front of the bodies of the tenth and eleventh thoracic vertebrae, the lesser sac of peritoneum, diaphragm and thoracic aorta intervening. To the left of this is the fissure for the ductus venosus, and to the left of this again, the left lobe, in which a broad shallow groove for the oesophagus may usually be seen. Sometimes the left lobe stretches as far as the left abdominal wall, but more often it ends below the apex of the heart, which is 3 in. to the left of the mid line of the body. The relations of the lower surface can only be understood if it is realized that it looks backward and to the left as well as downward (see fig. I). Again starting from the right side, two impressions are seen; the anterior one is for the hepatic flexure of the colon, and the posterior for the upper part of the right kidney. To the left of the colic impression is a smaller one for the second part of the duodenum. Next comes the gall bladder, a pear-shaped bag, the fundus of which is in front and below, the neck behind and above. From the neck passes the cystic duct, which is often twisted into the form of an S. To the left of the gall bladder is the quadrate lobe, which is in contact with the pylorus of the stomach. To the left of this is the left lobe of the liver, separated from the quadrate lobe by the umbilical fissure in which lies the round ligament of the liver, the remains of the umbilical vein of the foetus. Sometimes this fissure is partly turned into a tunnel by a bridge of liver substance known as the pons hepatis. The under surface of the left lobe is concave for the interior surface of the stomach (see Alimentary Canal: Stomach Chamber), while a convexity, known as the tuber omentale, fits into the lesser curvature of that organ. The posterior boundary of the quadrate lobe is the transverse fissure, which is little more than an inch long and more than half an inch wide. This fissure represents the hilum of the liver, and contains the right and left hepatic ducts and the right and left branches of the hepatic artery and portal vein, together with nerves and lymphatics, the whole being enclosed in some condensed subperitoneal tissue known as Glisson's capsule. Behind the transverse fissure the lower end of the Spigelian lobe is seen as a knob called the tuber papillare, and from tree right of this a narrow bridge runs forward and to the right to join the Spigelian lobe to the right Vena cava in its fossa lobe and to shut off the transverse fissure from that for the vena cava. This is the caudate lobe. The right surface of the liver is covered with peritoneum and is in contact with the diaphragm, outside which are the pleura and lower ribs. From its lower margin the right lateral ligament is reflected on to the diaphragm. A similar fold passes from the tip of the left lobe as the left lateral ligament, and both these are the lateral margins of the coronary ligament. Sometimes, especially in women, a tongueshaped projection downward of the right lobe is found, known as Riedel's lobe; it is of clinical interest as it may be mistaken for a tumour or floating kidney (see C. H. Leaf, Proc. Anat. Soc., February 1899; Journ. Anat. and Phys. vol. 33, p. ix.). The right and left hepatic ducts, while still in the transverse fissure, unite into a single duct which joins the cystic duct from the gall bladder at an acute angle. When these have united the Spigelian lobe re of ductus venosus mental tuberosity ageal groove End of right suprarenal vein Suprarenal impression R; ght end of caudate lobe Uncovered area of right lobe Renal impression Attachment of right lateral ligament Fissu Portal fissure Umbilical fissure Quadrate lobe Portal vein Gall bladder Duodenal impression 0 Oesoph Cohc impressio; From A. Birmingham Cunningham's Text-book of Anatomy. FIG. I. - The Liver from below and behind, showing the whole of the visceral surface and the posterior area of the parietal surface. The portal fissure has been slightly opened up to show the vessels passing through it; the other fissures are represented in their natural condition - closed. In this liver, which was hardened in situ, the impressions of the sacculations of the colon are distinctly visible at the colic impression. The round ligament and the remains of the ductus venosus are hidden in the depths of their fissures.

duct is known as the common bile duct, and runs down to the second part of the duodenum (see Alimentary Canal). Minute Structure of the Liver. - The liver is made up of an enormous number of lobules of' ? a conical form (see fig. 3). If the portal vein is followed from the transverse fissure, it will be seen to branch and rebranch until minute twigs called interlobular veins (fig. 2, i) ramify around the lobules. From these intralobular capillaries run toward the centre of the lobule, forming a network among the polygonal hepatic cells. On reaching the core of the conical lobule they are collected into a central or intralobular vein (fig. 2, c) which unites with other similar ones to form a sublobular vein (fig. 3, s). These eventually reach the hepatic radicles, and so the blood is conducted into the vena cava. In man the lobules are not disftinctl se arated one from the other,but in some animals, e.g. the pig, each one has a fibrous sheath derived from Glisson's ca sule (fig. 3, ct.).

Embryology

The liver first appears as an ento dermal hollow longitudinal outgrowth from the duo denum into the ventral mesentery. The upper part of this forms the future liver, and grows up into the septum transversum from which the central part of the diaphragm is formed (see Diaphragm). From the cephalic part of this primary diverticulum solid rods of cells called the hepatic cylinders grow out, and these branch again and again until a cellular network is formed surrounding and breaking up the umbilical and vitelline veins. The liver cells, therefore, are entodermal, but the supporting connective tissue mesodermal from the septum transversum. The lower (caudal) part of the furrow-like outgrowth remains hollow and forms the gall bladder. At first the liver is embedded in the septum transversum, but later the diaphragm and it are constricted off one from the other, and soon the liver becomes very large and fills the greater part of the abdomen. At birth it is proportionately much larger than in the adult, and forms one eighteenth instead of one r ??"` fortieth of the body weight, /``? rG / i, the right and left lobes being -',;r©,? nearly equal in size.

`??? !j,` '1', /, e . Comparative Anatomy. - In ?/?/ i / the Acrania (Amphioxus) the ??? '?? ??? ? Z % liver is probably represented ?? ? / by a single ventral diver /? t t(t, ?l`? ? ? f ticulum from the anterior i ??1 ?i ? ?' ?a ?? end of the intestine, which ?? o????©????? has on hepatic portal circula 'a' 1? ti on and secretes digestive ????? %- fluid. In all the Craniata a = z ' ? ? solid liver is developed. In ... - / ,,,;- the adult lamprey among the Cyclostomata the liver underFIG. 3. - Vertical section through two goes retrogression, and the hepatic lobules of a pig. bile ducts and gall bladder disappear, though they are present in the larval form (Ammocoetes). In fishes and amphibians the organ consists of right and left lobes, and a gall-bladder is present. The same description applies to the reptiles, but a curious net work of cystic ducts is found in snakes and to a less extent in crocodiles. the Varanidae (Monitors) the hepatic duct is also retiform (see F. E. Beddard, Proc. Zool. Soc., 1888, p. 105). In birds two lobes are also present, but in some of them, e.g. the pigeon, there is no gall-bladder.

In mammals Sir William Flower pointed out that a generalized type of liver exists, from which that of any mammal may be derived by suppression or fusion of lobes. The accompanying diagram of Flower (fig. 4) represents an ideal mammalian liver. It will be seen that the umbilical fissure (u) divides the organ into right and left halves, as in the lower vertebrates, but that the ventral part of each half is divided into a central and lateral lobe. Passing from right to left there are therefore: right lateral (rl), right central (rc), left central (lc), and left lateral (11) lobes. The gall-bladder (g), when it is present, is always situated on the caudal surface or in the substance of the right central lobe. The Spigelian (s) and caudate lobes (c) belong to the right half of the liver, the latter being usually a leaf shaped lobe attached by its stalk to the Spigelian, and having its blade flattened between the right lateral lobe and the right kidney. The vena cava (vc) is always found to the right of the Spigelian lobe and dorsal to the stalk of the caudate. In tracing the lobulation of man's liver back to this generalized type, it is evident at once that his quadrate lobe does not correspond to any one generalized lobe, but is merely that part of the right central which lies between the gall bladder and the umbilical fissure. From a careful study of human variations (see A. Thomson, Journ. Anat. and Phys. vol. 33, p. 546) compared with an Anthropoid liver, such as that of the gorilla, depicted by W. H. L. Duckworth (Morphology and Anthro- FIG. 4. - Diagrammatic Plan of the Inferior Surface of a Multilobed Liver of a Mammal. The posterior or attached border is uppermost.

u, Umbilical vein of the foetus, rlf, The right lateral fissure. represented by the round cf, The cystic fissure. ligament in the adult, lying 11, The left lateral lobe. in the umbilical fissure. lc, The left central lobe.

dv, The ductus venosus. rc, The right central lobe.

vc, The inferior vena cava. rl, The right lateral lobe. p, The vena portae entering the s, The Spigelian lobe.

transverse fissure. c, The caudate lobe.

llf, The left lateral fissure. g, The gall bladder.

pology, Cambridge, 1904, p. 98), it is fairly clear that the human liver is formed, not by a suppression of any of the lobes of the generalized type, but by a fusion of those lobes and obliteration of certain fissures. This fusion is, probably correctly, attributed by Keith to the effect of pressure following the assumption of the erect position (Keith, Proc. Anat. Soc. of Gt. Britain, Journ. Anat. and Phys. vol. 33, p. xii.). The accom panying diagram (fig. 5) shows an abnormal human liver in the Anatomical Department of St Thomas's Hospital which reproduces the generalized type. In its lobulation it is singularly like, in many details, that of the baboon (Papio maimon) figured by G. Ruge (Morph. Jahrb., Bd. 35, p. 197); see F. G. Parsons, Proc. Anat. Soc., Feb. 1904, Journ. Anat. and Phys. vol. 33, p. xxiii. Georg Ruge " Die dusseren Formverha,ltnisse der Leber bei den Primaten," (Morph. Jahrb., Bd. 29 and _ 35) gives a critical study of FIG: 5. - Human Liver showing a the primate liver, and among reversion to the generalized mamother things suggests the remalian type.

cognition of the Spigelian and caudate lobes as parts of a single lobe, for which he proposes the name of lobus venae cavae. This doubtless would be an advantage morphologically, though for human descriptive anatomy the present nomenclature is not likely to be altered.

The gall-bladder is usually present in mammals, but is wanting in the odd-toed ungulates (Perissodactyla) and Procavia (Hyrax). In the giraffe it may be absent or present. The cetacea and a few rodents are also without it. In the otter the same curious network of bile ducts already recorded in the reptiles is seen (see P. H. Burne, Proc. Anat. Soc., Journ. Anat. and Phys. vol. 33, p. xi.). (F. G. P.) Surgery Of Liver And Gall-Bladder. - EXpOSed as it is in the upper part of the abdomen, and being somewhat friable, the human liver is often torn or ruptured by blows or kicks, and, the large blood-vessels being thus laid open, fatal haemorrhage 2. - Transverse section through the hepatic lobules.

i, Interlobular veins ending in the intralobular capillaries.

c, c, Central veins joined by the intralobular capillaries. At a, a the capillaries of one lobule communicate with those adjacent to it.

FIG.

c, c, Central veins receiving the intralobular capillaries.

s, Sublobular vein.

ct, Interlobular connective tissue forming the capsules of the lobules.

i, 1, Interlobular veins.

into the belly-cavity may take place. The individual becomes faint, and the faintness keeps on increasing; and there are pain and tenderness in the liver-region. The right thing to do is to open the belly in the middle line, search for a wound in the liver and treat it by deep sutures, or by plugging it with gauze.

Cirrhosis of the Liver

As the result of chronic irritation of the liver increased supplies of blood pass to it, and if the irritation is unduly prolonged inflammation is the result. ,:The commonest causes of this chronic hepatitis are alcoholism and syphilis. The new fibrous tissue which is developed throughout the liver, as the result of the chronic inflammation, causes general enlargement of the liver with, perhaps, nausea, vomiting and jaundice. Later the new fibrous tissue undergoes contraction and the liver becomes smaller than natural. Blood then finds difficulty in passing through it, and, as a result, dropsy occurs in the belly (ascites). This may be relieved by tapping the cavity with a small hollow needle (Southey's trocar), or by passing into it a large sharp-pointed tube. This relieves the dropsy, but it does not cure the condition on which the dropsy depends. A surgical operation is sometimes undertaken with success for enabling the engorged veins to empty themselves into the blood-stream in a manner so as to avoid the liver-route.

Inflammation of the Liver (hepatitis) may also be caused by an attack of micro-organisms which have reached it through the veins coming from the large intestine, or through the main arteries. There are, of course, as the result, pain and tenderness, and there is often jaundice. The case should be treated by rest in bed, fomentations, calomel and saline aperients. But when the hepatitis is of septic origin, suppuration is likely to occur, the result being an hepatic abscess.

Hepatic Abscess is especially common in persons from the East who have recently undergone an attack of dysentery. In addition to the local pain and tenderness, there is a high temperature accompanied with shiverings or occasional rigors, the patient becoming daily more thin and miserable. Sometimes the abscess declares itself by a bulging at the surface, but if not an incision should be made through the belly-wall over the most tender spot, and a direct examination of the surface of the liver made. A bulging having been found, that part of the liver which apparently overlies the abscess should be stitched up to the sides of the opening made in belly-wall, and should then be explored by a hollow needle. Pus being found, the abscess should be freely opened and drained. It is inadvisable to explore for a suspected abscess with a hollow needle without first opening the abdomen, as septic fluid might thus be enabled to leak out, and infect the general peritoneal cavity. If an hepatic abscess is injudiciously left to itself it may eventually discharge into the chest, lungs or belly, or it may establish a communication with a piece of intestine. The only safe way for an abscess to evacuate itself is on to the surface of the body.

Hydatic Cysts are often met with in the liver. They are due to a peculiar development of the eggs of the tape-worm of the dog, which have been received into the alimentary canal with infected water or uncooked vegetables, such as watercress. The embryo of the taenia echinococcus finds its way from the stomach or intestine into a vein passing to the liver, and, settling itself in the liver, causes so much disturbance there that a capsule of inflammatory material forms around it. Inside this wall is the special covering of the embryo which shortly becomes distended with clear hydatid fluid. The cyst should be treated like a liver-abscess, by incision through the abdominal or thoracic wall, by circumferential suturing and by exploration and drainage.

Tumours of the Liver may be innocent or malignant. The most important of the former is the gumm y of tertiary syphilis; this may steadily and completely disappear under the influence of iodide of potassium. The commonest form of malignant tumour is the result of the growth of cancerous elements which have been brought to the liver by the veins coming up from a primary focus of the large intestine. Active surgical treatment of such a tumour is out of the question. Fortunately it is, as a rule, painless.

The Gall-bladder may be ruptured by external violence, and if bile escapes from the rent in considerable quantities peritonitis will be set up, whether the bile contains septic germs or not. If, on opening the abdomen to find out what serious effects some severe injury has caused, the gall-bladder be found torn, the rent may be sewn up, or, if thought better, the gall-bladder may be removed. The peritoneal surfaces in the region of the liver should then be wiped clean, and the abdominal wound closed, except for the passage through it of a gauze drain.

Biliary concretions, known as gall stones, are apt to form in the gall-bladder. They are composed of crystals of bile-fat, cholesterine. Sometimes in the course of a post-mortem examination a gall-bladder is found packed full of gall-stones which during life had caused no inconvenience and had given rise to no suspicion of their presence. In other cases gall-stones set up irritation in the gall-bladder which runs on to inflammation, and the gall-bladder being infected by septic germs from the intestine (bacilli coli) an abscess forms.

Abscess of the Gall-bladder gives rise to a painful, tender swelling near the cartilage of the ninth rib of the right side. If the abscess is allowed to take its course, adhesions may form around it and it may burst into the intestine or on to the surface of the abdomen, a biliary fistula remaining. Abscess in the gall-bladder being suspected, an incision should be made down to it, and, its covering having been stitched to the abdominal wall, the gall-bladder should be opened and drained. The presence of concretions in the gall-bladder may not only lead to the formation of abscess but also to invasion of the gall-bladder by cancer.

Stones in the gall-bladder should be removed by operation, as, if left, there is a great risk of their trying to escape with the bile into the intestine and thus causing a blockage of the common bile-duct, and perhaps a fatal leakage of bile into the peritoneum through a perforating ulcer of the duct. If before opening the gall-bladder the surface is stitched to the deepest part of the abdominal wound, the biliary fistula left as the result of the opening of the abscess will close in due course.

" Biliary colic " is the name given to the distressing symptoms associated with the passage of a stone through the narrow bileduct. The individual is doubled up with acute pains which, starting from the hepatic region, spread through the abdomen and radiate to the right shoulder blade. Inasmuch as the stone is blocking the duct, the bile is unable to flow into the intestine; so, being absorbed by the blood-vessels, it gives rise to jaundice. The distress is due to spasmodic muscular contraction, and it comes on at intervals, each attack increasing the patient's misery. He breaks out into profuse sweats and may vomit. If the stone happily finds its way into the intestine the distress suddenly ceases. In the meanwhile relief may be afforded by fomentations, and by morphia or chloroform, but if no prospect of the stone escaping into the intestine appears likely, the surgeon will be called upon to remove it by an incision through the gall-bladder, or the bile-duct, or through the intestine at the spot where it is trying to make its escape. Sometimes a gall-stone which has found its way into the intestine is large enough to block the bowel and give rise to intestinal obstruction which demands abdominal section.

A person who is of what used to be called a " biliary nature " should live sparingly and take plenty of exercise. He should avoid fat and rich food, butter, pastry and sauces, and should drink no beer or wine - unless it be some very light French wine or Moselle. He should keep his bowels regular, or even loose, taking every morning a dose of sulphate of soda in a glass of hot water. A course at Carlsbad, Vichy or Contrexeville, may be helpful. It is doubtful if drugs have any direct influence upon gall-stones, such as sulphate of soda, olive oil or oleate of soda. No reliance can be placed upon massage in producing the onward passage of a gall-stone from the gall-bladder towards the intestine. Indeed this treatment might be not only distressing but harmful. (E. O.*)


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From BibleWiki

(Heb. kabhed, "heavy;" hence the liver, as being the heaviest of the viscera, Ex 29:13, 22; Lev 3:4, 1, 10, 15) was burnt upon the altar, and not used as sacrificial food. In Ezek 21:21 there is allusion, in the statement that the king of Babylon "looked upon the liver," to one of the most ancient of all modes of divination. The first recorded instance of divination (q.v.) is that of the teraphim of Laban. By the teraphim the LXX. and Josephus understood "the liver of goats." By the "caul above the liver," in Lev 4:9; 7:4, etc., some understand the great lobe of the liver itself.

This entry includes text from Easton's Bible Dictionary, 1897.

what mentions this? (please help by turning references to this page into wiki links)

This article needs to be merged with LIVER (Jewish Encyclopedia).

Simple English

The liver is an organ in the abdomen. It is part of the gastrointestinal system. Sometimes people use hepato- as a prefix when they talk about the liver. For example if people talk about liver cells, they say hepatocellular. Another word for liver cell is hepatocyte (-cyte means cell.)

File:Digestive system showing bile
Liver and digestive system

Contents

What the liver does

The liver does many important things in the body:

  • The liver makes bile. This is a yellow-green liquid that goes into the small intestines to help digest the food we eat.
  • The liver stores glucose when we eat and then puts the glucose into the blood when our blood glucose level goes down (when we have not eaten for a while.)
  • The liver takes protein and fat and turns it into glucose. This is important if we have no food to eat. We can use the fat we have saved, and make it into glucose to use.
  • The liver also makes some fats and cholesterol
  • The liver metabolizes (breaks down) many things in the blood:
  • The liver stores (keeps) vitamins and minerals
  • The liver makes many proteins:
  • In fetuses when they are very small, the liver makes red blood cells

Liver diseases

There are many different liver diseases. Liver disease can make someone very very sick because of all the important work the liver does. People who have bad liver disease usually die unless they can get a Liver transplant. This is where the liver from someone who has just died is put in another person. This is very difficult surgery. But surgeons do it because it can save a person's life.

Symptoms of liver disease

The symptoms of liver disease happen because the liver does not do the work it should.

The liver cannot metabolize (break down) toxins and waste so these bad things stay in the blood longer than they otherwise would. One thing that builds up is a substance called bilirubin. When red blood cells die, the hemoglobin in them leaks into the blood. The hemoglobin becomes bilirubin (a yellow substance that makes bile yellow.) The liver takes the bilirubin out of the blood and puts it into the bile. The bile goes into the intestines and then goes out with the waste from your body. If the liver is hurt, it does not remove the bilirubin, so the bilirubin stays in the body. This makes the person's body look yellow and is known as jaundice. So yellow eyes and yellow skin are symptoms of liver disease.

Other symptoms of liver disease are:

  • Bleeding because the liver does not make enough coagulation proteins (to make clots)
  • Swelling of body. If the swelling is of the abdomen it is called ascites
  • Confusion and acting very tired because of the extra ammonia that the liver cannot metabolize
  • Bleeding from very big swollen veins in the esophagus called esophageal varices. If these bleed, it can cause the person to die very quickly.

Types of liver disease

Hepatitis is when liver cells get inflamed (sick.) This can be from virus infections. This can be from toxins or poisons. (The most common toxin to cause hepatitis is alcohol.) This can be from genetic disease. This can be from autoimmune diseases when the body's immune system hurts itself.

Cirrhosis is from death of liver cells that happens again and again. When the cells die, scar tissue forms. This scar tissue damages the structure of the liver. This makes the liver not work as well. But it also makes the pressure in the veins that go to the liver very high. This high pressure makes esophageal varices. The most common reason for cirrhosis in the world is hepatitis B virus infection.

Some diseases cause bad things to build up in the liver. Hemochromatosis causes extra iron to build up in the liver. Wilson's disease causes extra copper to build up in the liver. Both of these diseases hurt the cells and can cause very bad liver disease that kills people.

You can also get cancer of your liver. This can be metastatic cancer that came from some other place in your body. The liver is a common place to get metastases because it takes bad things out of the blood. So it takes cancer cells out of the blood and they grow in the liver. Cancer can also grow from the liver. If it grows from the liver it is called hepatocellular carcinoma (liver cell cancer) if it is from liver cells. Most hepatocellular carcinoma is from cirrhosis. If it is from the cells that line the bile ducts in the liver, it is called cholangiocarcinoma.

Treatments for liver disease

Some liver diseases can be treated easily with medicine. Hemochromatosis is treated just by taking blood from people every 2 months.

Some liver diseases can be stopped before they start. Two types of viral hepatitis can be stopped with an immunization. Hepatitis A and B viruses can be stopped with a total of 5 shots in a person's life.

Some liver diseases can only be treated with liver transplant.

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