Sinusoid of a rat liver with fenestrated endothelial cells. Fenestrae are approx 100 nm diameter, and the sinusoidal width 5 µm. Scanning electron micrograph by Robin Fraser, University of Otago.

Human liver

Hepatocytes make up 70-80% of the cytoplasmic mass of the liver. These cells are involved in protein synthesis, protein storage and transformation of carbohydrates, synthesis of cholesterol, bile salts and phospholipids, and detoxification, modification and excretion of exogenous and endogenous substances. The hepatocyte also initiates the formation and secretion of bile. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Species 50 species; see text *Several subfamilies of Muroids include animals called rats. ... A nanometre (American spelling: nanometer, symbol nm) (Greek: νάνος, nanos, dwarf; μετρώ, metrό, count) is a unit of length in the metric system, equal to one billionth of a metre (or one millionth of a millimetre), which is the current SI base unit of length. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... The University of Otago (Māori: ) in Dunedin is New Zealands oldest university with over 20,000 students enrolled during 2006. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Cross section of cell with cytoplasm labeled at center right. ... For the bird, see Liver bird. ... Protein synthesis is the creation of proteins using DNA and RNA. Biological and artificial methods for creation of proteins differ significantly. ... Lactose is a disaccharide found in milk. ... Cholesterol is a sterol (a combination steroid and alcohol). ... Bile is also another name for Belenus, a god in Brythonic mythology. ... Phospholipid Two schematic representations of a phospholipid. ... Bile (or gall) is a bitter, yellow or green alkaline fluid secreted by hepatocytes from the liver of most vertebrates. ...

[edit] Hepatocyte histology

Hepatocytes display an eosinophilic cytoplasm, reflecting numerous mitochondria, and basophilic stippling due to large amounts of rough endoplasmic reticulum and free ribosomes. Brown lipofuscin granules are also observed (with increasing age) together with irregular unstained areas of cytoplasm; these correspond to cytoplasmic glycogen and lipid stores removed during histological preparation. The average life span of the hepatocyte is 5 months; they are able to regenerate. Eosinophilic is a technical term used by histologists. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... Basophilic is a technical term used by histologists. ... The endoplasmic reticulum or ER (endoplasmic means within the cytoplasm, reticulum means little net) is an organelle found in all eukaryotic cells. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Lipofuscin is the name given to brown pigment granules composed of lipid-containing residues of lysosomal digestion. ... This article does not cite any references or sources. ... Some common lipids. ...

Hepatocyte nuclei are round with dispersed chromatin and prominent nucleoli. Anisokaryosis is common and reflects tetraploidy & polyploidy, a normal feature of over 50% of hepatocytes. Binucleate cells are also common. Hepatocytes are organised into plates separated by vascular channels (sinusoids), an arrangement supported by a reticulin (collagen type III) network. The hepatocyte plates are one cell thick in mammals and two cells thick in the chicken. Sinusoids display a discontinuous, fenestrated endothelial cell lining. The endothelial cells have no basement membrane and are separated from the hepatocytes by the space of Disse which drains lymph into the portal tract lymphatics. Kupffer cells are scattered between endothelial cells; they are part of the reticuloendothelial system and phagocytose spent erythrocytes. Stellate (Ito) cells store vitamin A and produce extracellular matrix and collagen; they are also distributed amongst endothelial cells but are difficult to visualise by light microscopy. HeLa cells stained for DNA with the Blue Hoechst dye. ... Chromatin is the complex of DNA and protein found inside the nuclei of eukaryotic cells. ... In biology, the nucleolus is, strictly speaking, a suborganelle of the cell nucleus, which is an organelle. ... Polyploid (in Greek: πολλαπλόν - multiple) cells or organisms contain more than one copy (ploidy) of their chromosomes. ... Polyploidy refers to cells or organisms that contain more than two copies of each of their chromosomes. ... Sinusoid of a rat liver with fenestrated endothelial cells. ... The endothelium is the layer of thin, flat cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. ... ... In mammals including humans, the lymphatic vessels (or lymphatics) are a network of thin tubes that branch, like blood vessels, into tissues throughout the body. ... Lymph originates as blood plasma lost from the circulatory system, which leaks out into the surrounding tissues. ... The reticuloendothelial system (RES), part of the immune system, consists of the phagocytic cells located in reticular connective tissue, primarily monocytes and macrophages. ... Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ... The structure of retinol, the most common dietary form of vitamin A Vitamin A is an essential human nutrient. ... Illustration depicting extracellular matrix (basement membrane and interstitial matrix) in relation to epithelium, endothelium and connective tissue In biology, the extracellular matrix (ECM) is the extracellular part of animal tissue that usually provides structural support to the cells in addition to performing various other important functions. ... Tropocollagen triple helix. ...

Hepatocytes are an important physiological example for evalutation of both biological and metabolic effects of xenobiotics. They do not proliferate in culture. Hepatocytes are intensely sensitive to damage during the cycles of cryopreservation including freezing and thawing. Even after the addition of classical cryoprotectants there is still damage done while being cryopreserved. ^[1] A xenobiotic is a chemical which is found in an organism but which is not normally produced or expected to be present in it. ...

[edit] Protein synthesis

The hepatocyte is a cell in the body that manufactures serum albumin, fibrinogen, and the prothrombin group of clotting factors. It is the main site for the synthesis of lipoproteins, ceruloplasmin, transferrin, complement and glycoproteins. Hepatocytes manufacture their own structural proteins and intracellular enzymes. Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... For other uses, see Body (disambiguation). ... You may be looking for albumen, or egg white. ... Fibrin is a protein involved in the clotting of blood. ... Thrombin (activated Factor II) is a coagulation protein that has many effects in the coagulation cascade. ... Coagulation is the thickening or congealing of any liquid into solid clots. ... A lipoprotein is a biochemical assembly that contains both proteins and lipids. ... Ceruloplasmin Ceruloplasmin (or caeruloplasmin), officially known as ferroxidase or iron(II):oxygen oxidoreductase, is a copper transport protein found in the blood. ... Transferrin is a plasma protein for iron ion delivery. ... A complement protein attacking an invader. ... N-linked protein glycosylation (N-glycosylation of N-glycans) at Asn residues (Asn-x-Ser/Thr motifs) in glycoproteins[1]. Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide backbones. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ...

Synthesis of proteins is undertaken by the rough endoplasmic reticulum (RER), and both the rough and smooth endoplasmic reticulum (SER) are involved in secretion of the proteins formed. The endoplasmic reticulum (ER) is involved in conjugation of proteins to lipid and carbohydrate moieties synthesized by, or modified within, the hepatocytes. The endoplasmic reticulum or ER (endoplasmic means within the cytoplasm, reticulum means little net) is an organelle found in all eukaryotic cells. ... The endoplasmic reticulum or ER (endoplasmic means within the cytoplasm, reticulum means little net) is an organelle found in all eukaryotic cells. ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ...

[edit] Carbohydrate metabolism

The liver forms fatty acids from carbohydrates and synthesizes triglycerides from fatty acids and glycerol. Hepatocytes also synthesize apoproteins with which they then assemble and export lipoproteins (VLDL, HDL). For the bird, see Liver bird. ... Lactose is a disaccharide found in milk. ... An apoprotein is a protein without its characteristic prosthetic group. ... Very Low Density Lipoprotein (VLDL) is a lipoprotein subclass. ... High-density lipoproteins (HDL) form a class of lipoproteins, varying somewhat in their size (8–11 nm in diameter), that carry cholesterol from the bodys tissues to the liver. ...

[edit] Lipid metabolism

The liver receives many lipids from the systemic circulation and metabolizes chylomicron remnants. It also synthesizes cholesterol from acetate and then further synthesizes bile salts. The liver is the sole site of formation of bile salts. Some common lipids. ... Chylomicrons are large lipoprotein particles (having a diameter of 75 to 1,200nm) that are created by the absorptive cells of the small intestine. ... Cholesterol is a sterol (a combination steroid and alcohol). ... An acetate, or ethanoate, is a salt or ester of acetic acid. ... Bile is also another name for Belenus, a god in Brythonic mythology. ...

[edit] Detoxification

Hepatocytes have the ability to metabolize, detoxify, and inactivate exogenous compounds such as drugs and insecticides, and endogenous compounds such as steroids. This article does not cite any references or sources. ... It has been suggested that ovicide be merged into this article or section. ... This article is about the chemical family of steroids. ...

The drainage of the intestinal venous blood into the liver requires efficient detoxification of miscellaneous absorbed substances to maintain homeostasis and protect the body against ingested toxins. The intestine is the portion of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine. ... In geology, a vein is a regularly shaped and lengthy occurrence of an ore; a lode. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... For the bird, see Liver bird. ... Homeostasis is the property of either an open system or a closed system, especially a living organism, which regulates its internal environment so as to maintain a stable, constant condition. ...

One of the detoxifying functions of hepatocytes is to modify ammonia into urea for excretion. Urea is an organic compound with the chemical formula (NH2)2CO. Urea is also known as carbamide, especially in the recommended International Nonproprietary Names (rINN) in use in Europe. ...

[edit] Additional images

Schemic diagram of Biliary system Image File history File links Size of this preview: 800 × 445 pixelsFull resolution‎ (3,110 × 1,729 pixels, file size: 497 KB, MIME type: image/jpeg) Diagram of biliary system and microscopy of hepatic parenchyma, not representative of relative size. ...

[edit] References

[edit] External links

• Histology at BU 22101ooa - "Ultrastructure of the Cell: hepatocytes and sinusoids"
• Hepatic Histology: Hepatocytes (Colorado State University