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106-441: 220296 72927 ENSG00000165478 ENSMUSG00000046240 Q14CZ8 Q640R3 NM_152722 NM_175189 NP_689935 NP_780398 Gene HEPACAM *, named based on its original site of identification - hepa tocytes and the nature of its protein product - a cell adhesion molecule ( CAM ), was first discovered and characterised in human liver . The gene encodes a protein of 416 amino acids, designated as hepaCAM**, which
212-426: A benign tumour the most common type of liver tumour, thought to be congenital. A genetic disorder causing multiple cysts to form in the liver tissue, usually in later life, and usually asymptomatic, is polycystic liver disease . 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,
318-418: A central tendon , which forms the crest of the dome. Its peripheral part consists of muscular fibers that take origin from the circumference of the inferior thoracic aperture and converge to be inserted into a central tendon. The muscle fibres of the diaphragm radiate outward from the central tendon. While the diaphragm is one muscle, it is composed of two distinct muscle regions: the costal, which serves as
424-454: A hepatocellular carcinoma patient. These genes were subsequently evaluated against a panel of human HCC specimens, leading to the identification of a novel gene HEPN1 . Based on the sequence of HEPN1, the new gene HEPACAM was then isolated and characterised. Structurally, hepaCAM is a glycoprotein containing an extracellular domain with 2 Ig-like loops, a transmembrane region and a cytoplasmic domain. Matched to chromosome 11q24, gene HEPACAM
530-421: A pneumoperitoneum , in which there is gas in the abdomen. An X-ray may also be used to check for herniation. The adoption of a deeper breathing pattern typically occurs during physical exercise in order to facilitate greater oxygen absorption. During this process the diaphragm more consistently adopts a lower position within the body's core. In addition to its primary role in breathing, the diaphragm also plays
636-410: A dual blood supply from the hepatic portal vein and hepatic arteries. The hepatic portal vein delivers around 75% of the liver's blood supply and 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 remaining quarter of its blood flow. Oxygen is provided from both sources; about half of
742-408: A key role in this phenomenon. At birth, the liver comprises roughly 4% of body weight and weighs on average about 120 g (4 oz). Over the course of further development, it will increase to 1.4–1.6 kg (3.1–3.5 lb) but will only take up 2.5–3.5% of body weight. Hepatosomatic index (HSI) is the ratio of liver weight to body weight. In the growing fetus, a major source of blood to
848-437: A lower position to facilitate a higher IAP. Therefore, if a person's diaphragm position is lower in general, through deep breathing, then this assists the strengthening of their core during that period. This can be an aid in strength training and other forms of athletic endeavour. For this reason, taking a deep breath or adopting a deeper breathing pattern is typically recommended when lifting heavy weights. The existence of
954-399: A membrane separating the pharynx from the stomach can be traced widely among the chordates . Thus the model organism , the marine chordate lancelet , possesses an atriopore by which water exits the pharynx, which has been claimed (and disputed) to be homologous to structures in ascidians and hagfishes . The tunicate epicardium separates digestive organs from the pharynx and heart, but
1060-410: A population of the bipotential hepatoblasts. Hepatic stellate cells are derived from mesenchyme. After migration of hepatoblasts into the septum transversum mesenchyme, the hepatic architecture begins to be established, with liver sinusoids and bile canaliculi appearing. The liver bud separates into the lobes. The left umbilical vein becomes the ductus venosus and the right vitelline vein becomes
1166-430: A protective benefit against liver cancer for moderate coffee drinkers. A 2017 study revealed that the positive effects of caffeine on the liver were evident regardless of the coffee preparation method. Thoracic diaphragm The thoracic diaphragm , or simply the diaphragm ( / ˈ d aɪ ə f r æ m / ; Ancient Greek : διάφραγμα , romanized : diáphragma , lit. 'partition'),
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#17330861083201272-409: A role in the production of clotting factors, as well as red blood cell production. Some of the proteins synthesized by the liver include coagulation factors I (fibrinogen), II (prothrombin), V , VII , VIII , IX , X , XI , XII , XIII , as well as protein C , protein S and antithrombin . The liver is a major site of production for thrombopoietin , a glycoprotein hormone that regulates
1378-400: A secondary role in strengthening the posture of the core. This is especially evident during deep breathing where its generally lower position increases intra-abdominal pressure, which serves to strengthen the lumbar spine. The key to real core stabilization is to maintain the increased IAP while going through normal breathing cycles. [...] The diaphragm then performs its breathing function at
1484-420: A superficial division of the liver into a left and right lobe. From below, the two additional lobes are located between the right and left lobes, one in front of the other. A line can be imagined running from the left of the vena cava and all the way forward to divide the liver and gallbladder into two halves. This line is called Cantlie's line . Other anatomical landmarks include the ligamentum venosum and
1590-491: A thin diaphragm leads to greater lung compliance, which can contribute to respiratory failure. Furthermore, reduction in diaphragm thickness during the early stages of disease can serve as a prognostic marker in sepsis patients, and COVID-19 patients. The diaphragm is also involved in non-respiratory functions. It helps to expel vomit , feces , and urine from the body by increasing intra-abdominal pressure, aids in childbirth, and prevents acid reflux by exerting pressure on
1696-401: Is a "satellite" of hepatitis B virus (it can only infect in the presence of hepatitis B), and co-infects nearly 20 million people with hepatitis B, globally. Hepatic encephalopathy is caused by an accumulation of toxins in the bloodstream that are normally removed by the liver. This condition can result in coma and can prove fatal. Budd–Chiari syndrome is a condition caused by blockage of
1802-415: Is a dark reddish brown, wedge-shaped organ with two lobes of unequal size and shape. A human liver normally weighs approximately 1.5 kilograms (3.3 pounds) and has a width of about 15 centimetres (6 inches). There is considerable size variation between individuals, with the standard reference range for men being 970–1,860 grams (2.14–4.10 lb) and for women 600–1,770 g (1.32–3.90 lb). It
1908-409: Is a new member of the immunoglobulin superfamily of cell adhesion molecules ( IgSF CAM ). The main biological functions of hepaCAM include a) modulating cell-matrix adhesion and migration , and b) inhibiting cancer cell growth . (Note: *HEPACAM, gene name; **hepaCAM, protein name) Through differential screening of gene expression, over 200 genes were found to be either up- or down-regulated in
2014-424: Is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity . The diaphragm is the most important muscle of respiration , and separates the thoracic cavity , containing the heart and lungs , from the abdominal cavity : as the diaphragm contracts, the volume of the thoracic cavity increases, creating a negative pressure there, which draws air into
2120-407: Is both the heaviest internal organ 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, to the right of the stomach, and overlying the gallbladder . The liver is connected to two large blood vessels : the hepatic artery and the portal vein . The hepatic artery carries oxygen-rich blood from the aorta via
2226-457: Is capable of inducing senescence-like growth arrest via a p53/p21-dependent pathway. Moreover, hepaCAM is proteolytically cleaved near the transmembrane region. These findings indicate that the new Ig-like cell adhesion molecule hepaCAM is also a tumour suppressor . Mutations in the human HEPACAM gene are linked to forms of leukodystrophy , a group of inherited disorders characterized by degeneration of brain white matter. The protein produced from
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#17330861083202332-405: Is higher up (superior) to the left half, since the large liver rests beneath the right half of the diaphragm. There is also speculation that the diaphragm is lower on the other side due to heart's presence. Other mammals have diaphragms, and other vertebrates such as amphibians and reptiles have diaphragm-like structures, but important details of the anatomy may vary, such as the position of
2438-450: Is known as the duodenal impression. The inferior surface of the left lobe of the liver presents behind and to the left of the gastric impression. This is moulded over the upper front surface of the stomach, and to the right of this is a rounded eminence, the tuber omentale , which fits into the concavity of the lesser curvature of the stomach and lies in front of the anterior layer of the lesser omentum . Microscopically, each liver lobe
2544-449: Is responsible for the breakdown and excretion of many waste products. It plays a key role in breaking down or modifying 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 conjugated to avail excretion in bile or urine. The liver converts ammonia into urea as part of
2650-405: Is seen to be made up of hepatic lobules . The lobules are roughly hexagonal, and consist of plates of hepatocytes , and sinusoids radiating from a central vein towards an imaginary perimeter of interlobular portal triads. The central vein joins to the hepatic vein to carry blood out from the liver. A distinctive component of a lobule is the portal triad , which can be found running along each of
2756-405: 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 drainage duct of the liver, and a branch from this duct produces
2862-446: Is ubiquitously expressed in normal human tissues, with particularly high expression levels in the central nervous system (CNS), and is frequently suppressed in a variety of tumour types. Functionally, hepaCAM is involved in cell-extracellular matrix interactions and growth control of cancer cells, and is able to induce differentiation of glioblastoma cells. In cell signaling, hepaCAM directly interacts with F-actin and calveolin 1 , and
2968-413: Is uneven and concave. It is covered in peritoneum apart from where it attaches the gallbladder and the porta hepatis. The fossa of gallbladder lies to the right of the quadrate lobe, occupied by the gallbladder with its cystic duct close to the right end of porta hepatis. Several impressions on the surface of the liver accommodate the various adjacent structures and organs. Underneath the right lobe and to
3074-441: The ampulla of Vater . The liver plays a major role in carbohydrate, protein, amino acid, and lipid metabolism. The liver performs several roles in carbohydrate metabolism. The liver is responsible for the mainstay of protein metabolism , synthesis as well as degradation. All plasma proteins except Gamma-globulins are synthesised in the liver. It is also responsible for a large part of amino acid synthesis . The liver plays
3180-415: The cardia of the stomach and the oesophagus disappear. Not all hiatus hernias cause symptoms however, although almost all people with Barrett's oesophagus or oesophagitis have a hiatus hernia. Hernias may also occur as a result of congenital malformation, a congenital diaphragmatic hernia . When the pleuroperitoneal membranes fail to fuse, the diaphragm does not act as an effective barrier between
3286-425: The celiac trunk , whereas the portal vein carries blood rich in digested nutrients from the entire gastrointestinal tract and also from the spleen and pancreas . These blood vessels subdivide into small capillaries known as liver sinusoids , which then lead to hepatic lobules . Hepatic lobules are the functional units of the liver. Each lobule is made up of millions of hepatic cells (hepatocytes), which are
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3392-442: The duodenum to help with digestion . The liver's highly specialized tissue , consisting mostly of hepatocytes , regulates a wide variety of high-volume biochemical reactions, including the synthesis and breakdown of small and complex organic molecules, many of which are necessary for normal vital functions. Estimates regarding the organ's total number of functions vary, but is generally cited as being around 500. For this reason,
3498-401: The esophagus as it passes through the esophageal hiatus . In some non-human animals, the diaphragm is not crucial for breathing; a cow, for instance, can survive fairly asymptomatically with diaphragmatic paralysis as long as no massive aerobic metabolic demands are made of it. If either the phrenic nerve , cervical spine or brainstem is damaged, this will sever the nervous supply to
3604-421: The fibrinogen beta chain protein. Organogenesis , the development of the organs, takes place from the third to the eighth week during embryogenesis . The origins of the liver lie in both the ventral portion of the foregut endoderm (endoderm being one of the three embryonic germ layers ) and the constituents of the adjacent septum transversum mesenchyme . In the human embryo , the hepatic diverticulum
3710-399: The hepatic veins (including thrombosis ) that drain the liver. It presents with the classical triad of abdominal pain, ascites and liver enlargement . 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
3816-417: The inferior vena cava and left suprarenal vein . The sternal portion of the muscle is sometimes wanting and more rarely defects occur in the lateral part of the central tendon or adjoining muscle fibers. The thoracic diaphragm develops during embryogenesis , beginning in the third week after fertilization with two processes known as transverse folding and longitudinal folding. The septum transversum ,
3922-432: The internal intercostal muscles used in conjunction with the abdominal muscles , which act as an antagonist paired with the diaphragm's contraction. Diaphragm dysfunction is a well-known factor associated with various complications in patients, such as prolonged respiratory failure, difficulties in weaning from mechanical ventilation, extended hospitalization, increased morbidity, and mortality. Studies have reported that
4028-428: The ornithine cycle or the urea cycle, and the urea is excreted in the urine. Because the liver is an expandable organ, large quantities of blood can be stored in its blood vessels. Its normal blood volume, including both that in the hepatic veins and that in the hepatic sinuses, is about 450 milliliters, or almost 10 percent of the body's total blood volume. When high pressure in the right atrium causes backpressure in
4134-403: The right and left triangular ligaments . These peritoneal ligaments are not related to the anatomic ligaments in joints, and the right and left triangular ligaments have no known functional importance, though they serve as surface landmarks. The falciform ligament functions to attach the liver to the posterior portion of the anterior body wall. The visceral surface or inferior surface
4240-410: The round ligament of the liver , which further divide the left side of the liver in two sections. An important anatomical landmark, the porta hepatis , divides this left portion into four segments, which can be numbered starting at the caudate lobe as I in an anticlockwise manner. From this parietal view, seven segments can be seen, because the eighth segment is only visible in the visceral view. On
4346-433: The thorax and abdomen , fluid abnormally present in the thorax, or air abnormally present in the abdomen, may collect on one side of the diaphragm. An X-ray may reveal this. Pleural effusion , in which there is fluid abnormally present between the two pleurae of the lungs , is detected by an X-ray of the chest, showing fluid collecting in the angle between the ribs and diaphragm . An X-ray may also be used to reveal
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4452-555: The HEPACAM gene was found to interact with the gene products of MLC1 and CLCN2 , two other human genes linked to leukodystrophies. Metastatic canine mammary carcinoma and their metastases are characterized by decreased HEPACAM2 but unchanged HEPACAM2 expression levels when compared to normal glands. Human liver The liver is a major metabolic organ exclusively found in vertebrate animals , which performs many essential biological functions such as detoxification of
4558-513: The abdomen and thorax. Herniation is usually of the left, and commonly through the posterior lumbocostal triangle , although rarely through the anterior foramen of Morgagni . The contents of the abdomen, including the intestines , may be present in the thorax, which may impact development of the growing lungs and lead to hypoplasia . This condition is present in 0.8 - 5/10,000 births. A large herniation has high mortality rate, and requires immediate surgical repair. Due to its position separating
4664-504: 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 produces insulin-like growth factor 1 , a polypeptide protein hormone that plays an important role in childhood growth and continues to have anabolic effects in adults. The liver is responsible for the breakdown of insulin and other hormones . The liver breaks down bilirubin via glucuronidation , facilitating its excretion into bile. The liver
4770-482: The alligator diaphragmaticus muscle does not insert on the esophagus and does not affect pressure of the lower esophageal sphincter. The lungs are located in the abdominal compartment of amphibians and reptiles, so that contraction of the diaphragm expels air from the lungs rather than drawing it into them. In birds and mammals, lungs are located above the diaphragm. The presence of an exceptionally well-preserved fossil of Sinosauropteryx , with lungs located beneath
4876-450: The anus returns to the upper compartment to discharge wastes through an outgoing siphon. Thus the diaphragm emerges in the context of a body plan that separated an upper feeding compartment from a lower digestive tract, but the point at which it originates is a matter of definition. Structures in fish, amphibians, reptiles, and birds have been called diaphragms, but it has been argued that these structures are not homologous . For instance,
4982-403: The basic metabolic cells. The lobules are held together by a fine, dense, irregular, fibroelastic connective tissue layer extending from the fibrous capsule covering the entire liver known as Glisson's capsule after British doctor Francis Glisson . This tissue extends into the structure of the liver by accompanying the blood vessels, ducts, and nerves at the hepatic hilum. The whole surface of
5088-455: The blood and constitute plasma proteins and hepatokines . Other liver-specific proteins are certain liver enzymes such as HAO1 and RDH16 , proteins involved in bile synthesis such as BAAT and SLC27A5 , and transporter proteins involved in the metabolism of drugs, such as ABCB11 and SLC2A2 . Examples of highly liver-specific proteins include apolipoprotein A II , coagulation factors F2 and F9 , complement factor related proteins , and
5194-520: The blood and excretes it through bile. Other disorders caused by excessive alcohol consumption are grouped under alcoholic liver diseases and these include alcoholic hepatitis , fatty liver , and cirrhosis . Factors contributing to the development of alcoholic liver diseases are not only the quantity and frequency of alcohol consumption, but can also include gender, genetics, and liver insult. Liver damage can also be caused by drugs , particularly paracetamol and drugs used to treat cancer. A rupture of
5300-406: The center of the vault formed by the muscle, closer to the front than to the back of the thorax . The central part of the tendon is attached above to pericardium . The both sides of the posterior fibres are attached to paracolic gutters (the curving of ribs before attaching to both sides of the vertebral bodies). There are a number of openings in the diaphragm through which structures pass between
5406-467: The centre of each segment are branches of the portal vein, hepatic artery, and bile duct. In the periphery of each segment is vascular outflow through the hepatic veins. The classification system uses the vascular supply in the liver to separate the functional units (numbered I to VIII) with unit 1, the caudate lobe, receiving its supply from both the right and the left branches of the portal vein. It contains one or more hepatic veins which drain directly into
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#17330861083205512-419: The cervical spinal cord (C3,4, and 5). As the septum transversum descends inferiorly, the phrenic nerve follows, accounting for its circuitous route from the upper cervical vertebrae, around the pericardium , finally to innervate the diaphragm. The diaphragm is the main muscle of respiration and functions in breathing . During inhalation, the diaphragm contracts and moves in the inferior direction, enlarging
5618-414: The common hepatic duct to form the common bile duct. The biliary system and connective tissue is supplied by the hepatic artery alone. Bile either drains directly into the duodenum via the common bile duct, or is 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 hepatopancreatic ampulla, also known as
5724-406: The decomposition of red blood cells . The liver is also an accessory digestive organ that produces bile , an alkaline fluid containing cholesterol and bile acids , which emulsifies and aids the breakdown of dietary fat . The gallbladder , a small hollow pouch that sits just under the right lobe of liver, stores and concentrates the bile produced by the liver, which is later excreted to
5830-419: The diaphragm as in crocodiles, has been used to argue that dinosaurs could not have sustained an active warm-blooded physiology, or that birds could not have evolved from dinosaurs. An explanation for this (put forward in 1905), is that lungs originated beneath the diaphragm, but as the demands for respiration increased in warm-blooded birds and mammals, natural selection came to favor the parallel evolution of
5936-458: The diaphragm receives blood from branches of the internal thoracic arteries , namely the pericardiacophrenic artery and musculophrenic artery ; from the superior phrenic arteries , which arise directly from the thoracic aorta ; and from the lower internal intercostal arteries . From below, the inferior phrenic arteries supply the diaphragm. The diaphragm drains blood into the brachiocephalic veins , azygos veins , and veins that drain into
6042-444: The diaphragm. The diaphragm is primarily innervated by the phrenic nerve which is formed from the cervical nerves C3, C4 and C5. While the central portion of the diaphragm sends sensory afferents via the phrenic nerve, the peripheral portions of the diaphragm send sensory afferents via the intercostal (T5–T11) and subcostal nerves (T12). Arteries and veins above and below the diaphragm supply and drain blood. From above,
6148-418: The diaphragm. The most common damage to the phrenic nerve is by bronchial cancer , which usually only affects one side of the diaphragm. Other causes include Guillain–Barré syndrome and systemic lupus erythematosus . A hiatus hernia is a hernia common in adults in which parts of the lower esophagus or stomach that are normally in the abdomen pass/bulge abnormally through the diaphragm and are present in
6254-401: The diaphragmatic surface, apart from a triangular bare area where it connects to the diaphragm, the liver is covered by a thin, double-layered membrane, the peritoneum , that helps to reduce friction against other organs. This surface covers the convex shape of the two lobes where it accommodates the shape of the diaphragm. The peritoneum folds back on itself to form the falciform ligament and
6360-527: The driver in the work of breathing, and crural diaphragm, which serves as an "anchor;" attaching the muscle to the lower ribs and lumbar vertebrae. The costal diaphragm is further divided into ventral, medial, and dorsal costal portions. The vertebral part of the diaphragm arises from the crura and arcuate ligaments. Right crus arises from L1-L3 vertebral bodies and their intervertebral discs. Smaller left crus arises from L1, L2 vertebral bodies and their intervertebral discs. Medial arcuate ligament arises from
6466-418: The edge of the liver lobule, where they merge to form bile ducts. Within the liver, these ducts are termed intrahepatic bile ducts, and once they exit the liver, they are considered extrahepatic. The intrahepatic ducts eventually drain into the right and left hepatic ducts, which exit the liver at the transverse fissure , and merge to form the common hepatic duct. The cystic duct from the gallbladder joins with
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#17330861083206572-564: The family Herpesviridae such as the herpes simplex virus . Chronic (rather than acute) infection with hepatitis B virus or hepatitis C virus is the main cause of liver cancer . Globally, about 248 million individuals are chronically infected with hepatitis B (with 843,724 in the U.S.), and 142 million are chronically infected with hepatitis C (with 2.7 million in the U.S.). Globally there are about 114 million and 20 million cases of hepatitis A and hepatitis E respectively, but these generally resolve and do not become chronic. Hepatitis D virus
6678-414: The fascia thickening from body of L2 vertebrae to transverse process of L1 vertebrae, crossing over the body of the psoas major muscle. The lateral arcuate ligament arises from the transverse process of L1 vertebrae and is attached laterally to the 12th rib. The lateral arcuate ligament also arises from fascia thickening that covers the quadratus lumborum muscle. The median arcuate ligament arises from
6784-406: The fibrous parts of right and left crura where descending thoracic aorta passes behind it. No diaphramatic muscle arises from the median arcuate ligament. Both adrenal glands lie near the diaphragmatic crus and arcuate ligament. The costal part of diaphragm arises from the lower four ribs (7 to 10) costal cartilages. The central tendon of the diaphragm is a thin but strong aponeurosis near
6890-444: The fixed-volume, non-expansive lungs. A complicated system of valves and air sacs cycles air constantly over the absorption surfaces of the lungs so allowing maximal efficiency of gaseous exchange. Thus, birds do not have the reciprocal tidal breathing flow of mammals. On careful dissection, around eight air sacs can be clearly seen. They extend quite far caudally into the abdomen. [REDACTED] This article incorporates text in
6996-448: 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 that receives blood flow from both the right- and left-sided vascular branches. The Couinaud classification divides the liver into eight functionally independent liver segments. Each segment has its own vascular inflow, outflow and biliary drainage. In
7102-485: 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 liver lobule dictating expression of metabolic genes involved in drug metabolism, carbohydrate metabolism , ammonia detoxification, and bile production and secretion. WNT/β-catenin has now been identified to be playing
7208-412: The gallbladder. Besides signals from the septum transversum mesenchyme, fibroblast growth factor from the developing heart also contributes 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 liver bud . Their expansion forms
7314-419: The heart. The aorta does not pierce the diaphragm but rather passes behind it in between the left and right crus. There are several structures that pierce through the diaphragm, including: left phrenic nerve pierces through the central tendon, greater, lesser, and least thoracic splanchnic nerves pierces through bilateral crura, and lymphatic vessels that pierce throughout the diaphragam, especially behind
7420-427: The herniation of the lungs from the abdominal cavity in both lineages. However, birds do not have diaphragms. They do not breathe in the same way as mammals and do not rely on creating a negative pressure in the thoracic cavity, at least not to the same extent. They rely on a rocking motion of the keel of the sternum to create local areas of reduced pressure to supply thin, membranous airsacs cranially and caudally to
7526-405: The imaginary plane, 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 segment by the right hepatic vein. The left lobe is divided into the medial and lateral segments by
7632-437: The inferior vena cava, allowing placental blood to bypass the liver. In the fetus, the liver does not perform the normal digestive processes and filtration of the infant liver because nutrients are received directly from the mother via the placenta . The fetal liver releases some blood stem cells that migrate to the fetal thymus , creating the T cells (or T lymphocytes). After birth, the formation of blood stem cells shifts to
7738-463: The inferior vena cava. The remainder of the units (II to VIII) are numbered in a clockwise fashion: About 20,000 protein coding genes are expressed in human cells and 60% of these genes are expressed in a normal, adult liver. Over 400 genes are more specifically expressed in the liver, with some 150 genes highly specific for liver tissue. A large fraction of the corresponding liver-specific proteins are mainly expressed in hepatocytes and secreted into
7844-405: The insertion (central tendon) which works in conjunction with other muscles to allow the ribs to slide and the thoracic cavity to expand laterally and upwards. When the diaphragm relaxes (moves in the superior direction), air is exhaled by elastic recoil process of the lung and the tissues lining the thoracic cavity. Assisting this function with muscular effort (called forced exhalation ) involves
7950-423: The left hepatic vein. The hilum of the liver is described in terms of three plates that contain the bile ducts and blood vessels. The contents of the whole plate system are surrounded by a sheath. The three plates are the hilar plate , the cystic plate and the umbilical plate and the plate system is the site of the many anatomical variations to be found in the liver. In the widely used Couinaud system,
8056-445: The liver and drain into the inferior vena cava. The biliary tract is derived from the branches of the bile ducts. The biliary tract, also known as the biliary tree, is the path by which bile is secreted by the liver then transported to the first part of the small intestine, the duodenum . The bile produced in the liver is collected in bile canaliculi , small grooves between the faces of adjacent hepatocytes. The canaliculi radiate to
8162-492: The liver are carried out by the liver cells or hepatocytes. The liver is thought to be responsible for up to 500 separate functions, usually in combination with other systems and organs. Currently, no artificial organ or device is capable of reproducing all the functions of the liver. Some functions can be carried out by liver dialysis , an experimental treatment for liver failure . The liver also accounts for about 20% of resting total body oxygen consumption. The liver receives
8268-417: The liver can be caused by a liver shot used in combat sports. Primary biliary cholangitis is an autoimmune disease of the liver. It is marked by slow progressive destruction of the small bile ducts of the liver, with the intralobular ducts ( Canals of Hering ) affected early in the disease. When these ducts are damaged, bile and other toxins build up in the liver ( cholestasis ) and over time damages
8374-435: The liver has sometimes been described as the body's chemical factory . It is not known how to compensate for the absence of liver function in the long term, although liver dialysis techniques can be used in the short term. Artificial livers have not been developed to promote long-term replacement in the absence of the liver. As of 2018 , liver transplantation is the only option for complete liver failure . The liver
8480-490: The liver in response to injury or inflammation. The most common chronic liver disease is nonalcoholic fatty liver disease , which affects an estimated one-third of the world population. Hepatitis is a common condition of inflammation of the liver. The most usual cause of this is viral , and the most common of these infections are hepatitis A , B , C , D , and E . Some of these infections are sexually transmitted . Inflammation can also be caused by other viruses in
8586-404: 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
8692-419: The liver only produces symptoms after extensive damage. Hepatomegaly refers to an enlarged liver and can be due to many causes. It can be palpated in a liver span measurement. Consuming caffeine regularly may help safeguard individuals from liver cirrhosis . Additionally, it has been shown to slow the advancement of liver disease in those already affected, lower the risk of liver fibrosis, and provide
8798-584: The liver tissue in combination with ongoing immune related damage. This can lead to scarring ( fibrosis ) and cirrhosis . Cirrhosis increases the resistance to blood flow in the liver, and can result in portal hypertension . Congested anastomoses between the portal venous system and the systemic circulation, can be a subsequent condition. There are also many pediatric liver diseases, including biliary atresia , alpha-1 antitrypsin deficiency , alagille syndrome , progressive familial intrahepatic cholestasis , Langerhans cell histiocytosis and hepatic hemangioma
8904-467: The liver volume is occupied by parenchymal hepatocytes. Nonparenchymal cells constitute 40% of the total number of liver cells but only 6.5% of its volume. The liver sinusoids are lined with two types of cell, sinusoidal endothelial cells , and phagocytic Kupffer cells . Hepatic stellate cells are nonparenchymal cells found in the perisinusoidal space , between a sinusoid and a hepatocyte. Additionally, intrahepatic lymphocytes are often present in
9010-444: The liver's oxygen demand is met by the hepatic portal vein, and half is met by the hepatic arteries. The hepatic artery also has both alpha- and beta-adrenergic receptors; therefore, flow through the artery is controlled, in part, by the splanchnic nerves of the autonomic nervous system. Blood flows through the liver sinusoids and empties into the central vein of each lobule. The central veins coalesce into hepatic veins, which leave
9116-530: The liver, except for the bare area , is covered in a serous coat derived from the peritoneum , and this firmly adheres to the inner Glisson's capsule. Terminology related to the liver often starts in hepat- from ἡπατο-, from the Greek word for liver. The liver is grossly divided into two parts when viewed from above – a right and a left lobe – and four parts when viewed from below (left, right, caudate , and quadrate lobes ). The falciform ligament makes
9222-421: The liver, the liver expands, and 0.5 to 1 liter of extra blood is occasionally stored in the hepatic veins and sinuses. This occurs especially in cardiac failure with peripheral congestion. Thus, in effect, the liver is a large, expandable, venous organ capable of acting as a valuable blood reservoir in times of excess blood volume and capable of supplying extra blood in times of diminished blood volume. Because
9328-429: The lobule's corners. The portal triad consists of the hepatic artery, the portal vein, and the common bile duct. The triad may be seen on a liver ultrasound, as a Mickey Mouse sign with the portal vein as the head, and the hepatic artery, and the common bile duct as the ears. Histology , the study of microscopic anatomy, shows two major types of liver cell: parenchymal cells and nonparenchymal cells. About 70–85% of
9434-408: The lower ribs are stabilized and the central tendon of the diaphragm is mobile, a contraction brings the insertion (central tendon) towards the origins and pushes the lower cavity towards the pelvis, allowing the thoracic cavity to expand downward. This is often called belly breathing . When the central tendon is stabilized and the lower ribs are mobile, a contraction lifts the origins (ribs) up towards
9540-476: The lungs in the thoracic cavity. The diaphragm is an upward curved, c-shaped structure of muscle and fibrous tissue that separates the thoracic cavity from the abdomen. The superior surface of the dome forms the floor of the thoracic cavity, and the inferior surface the roof of the abdominal cavity. As a dome, the diaphragm has peripheral attachments to structures that make up the abdominal and chest walls. The muscle fibres from these attachments converge in
9646-431: The lungs. Its high oxygen consumption is noted by the many mitochondria and capillaries present; more than in any other skeletal muscle. The term diaphragm in anatomy, created by Gerard of Cremona , can refer to other flat structures such as the urogenital diaphragm or pelvic diaphragm , but "the diaphragm" generally refers to the thoracic diaphragm. In humans, the diaphragm is slightly asymmetric—its right half
9752-552: The lymph formed in the body under resting conditions arises in the liver. The liver is a vital organ and supports almost every other organ in the body. Because of its strategic location and multidimensional functions, the liver is prone to many diseases. The bare area of the liver is a site that is vulnerable to the passing of infection from the abdominal cavity to the thoracic cavity . Liver diseases may be diagnosed by liver function tests –blood tests that can identify various markers. For example, acute-phase reactants are produced by
9858-415: The opening is stretched open every time inspiration occurs. However, there has been argument that the caval opening actually constricts during inspiration. Since thoracic pressure decreases upon inspiration and draws the caval blood upwards toward the right atrium, increasing the size of the opening allows more blood to return to the heart, maximizing the efficacy of lowered thoracic pressure returning blood to
9964-432: The organism, and the synthesis of proteins and various other biochemicals necessary for digestion and growth. In humans , it is located in the right upper quadrant of the abdomen , below the diaphragm and mostly shielded by the lower right rib cage . Its other metabolic roles include carbohydrate metabolism , the production of hormones , conversion and storage of nutrients such as glucose and glycogen , and
10070-429: The pores in the hepatic sinusoids are very permeable and allow ready passage of both fluid and proteins into the perisinusoidal space , the lymph draining from the liver usually has a protein concentration of about 6 g/dl, which is only slightly less than the protein concentration of plasma. Also, the high permeability of the liver sinusoid epithelium allows large quantities of lymph to form. Therefore, about half of all
10176-753: The portal vein. The expanding liver bud is colonized by hematopoietic cells . The bipotential hepatoblasts begin differentiating into biliary epithelial cells and hepatocytes. 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 sinusoidal epithelial cells and bile canaliculi. Once hepatoblasts are specified into hepatocytes and undergo further expansion, they begin acquiring
10282-403: The presumptive esophagus, forming a barrier that separates the peritoneal and pleuropericardial cavities. Furthermore, dorsal mesenchyme surrounding the presumptive esophagus form the muscular crura of the diaphragm. Because the earliest element of the embryological diaphragm, the septum transversum, forms in the cervical region, the phrenic nerve that innervates the diaphragm originates from
10388-447: The primitive central tendon of the diaphragm, originates at the rostral pole of the embryo and is relocated during longitudinal folding to the ventral thoracic region. Transverse folding brings the body wall anteriorly to enclose the gut and body cavities. The pleuroperitoneal membrane and body wall myoblasts, from somatic lateral plate mesoderm , meet the septum transversum to close off the pericardio-peritoneal canals on either side of
10494-400: The production of platelets by the bone marrow. The liver plays several roles in lipid metabolism: it performs cholesterol synthesis, lipogenesis , and the production of triglycerides , and a bulk of the body's lipoproteins are synthesized in the liver. The liver plays a key role in digestion, as it produces and excretes bile (a yellowish liquid) required for emulsifying fats and help
10600-412: The red bone marrow . After 2–5 days, the umbilical vein and ductus venosus are obliterated; the former becomes the round ligament of liver and the latter becomes the ligamentum venosum. In the disorders of cirrhosis and portal hypertension , the umbilical vein can open up again. Unlike eutherian mammals, in marsupials the liver remains haematopoietic well after birth. The various functions of
10706-415: The right of the fossa , between the bare area and the caudate lobe, and immediately above the renal impression. The greater part of the suprarenal impression is devoid of peritoneum and it lodges the right suprarenal gland. Medial to the renal impression is a third and slightly marked impression, lying between it and the neck of the gall bladder. This is caused by the descending portion of the duodenum, and
10812-410: The right of the gallbladder fossa are two impressions, one behind the other and separated by a ridge. The one in front is a shallow colic impression, formed by the hepatic flexure and the one behind is a deeper renal impression accommodating part of the right kidney and part of the suprarenal gland . The suprarenal impression is a small, triangular, depressed area on the liver. It is located close to
10918-416: The sinusoidal lumen. The central area or hepatic hilum , includes the opening known as the porta hepatis which carries the common bile duct and common hepatic artery , and the opening for the portal vein. The duct, vein, and artery divide into left and right branches, and the areas of the liver supplied by these branches constitute the functional left and right lobes. The functional lobes are separated by
11024-464: The thorax and abdomen. There are three large openings — one for the aorta ( aortic hiatus ), one for the esophagus ( esophageal hiatus ), and one for the inferior vena cava (the caval opening ), as well as a series of smaller openings. The inferior vena cava passes through the caval opening, a quadrilateral opening at the junction of the right and middle leaflets of the central tendon , so that its margins are tendinous. Surrounded by tendons,
11130-413: The thorax. Hernias are described as rolling , in which the hernia is beside the oesophagus, or sliding , in which the hernia directly involves the esophagus. These hernias are implicated in the development of reflux, as the different pressures between the thorax and abdomen normally act to keep pressure on the esophageal hiatus . With herniation, this pressure is no longer present, and the angle between
11236-435: The volume of the thoracic cavity and reducing intra-thoracic pressure (the external intercostal muscles also participate in this enlargement), forcing the lungs to expand. In other words, the diaphragm's movement downwards creates a partial vacuum in the thoracic cavity, which forces the lungs to expand to fill the void, drawing air in the process. Cavity expansion happens in two extremes, along with intermediary forms. When
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