The+Liver+(K&S)



**Anatomy:**

 **Histology:  ** 
 * The liver is the largest glandular organ in the body, weighing about 3lbs. It is redish-brown in color and is divided into four lobes, unequal in both size and shape. The liver can be found in the right side of the abdominal cavity inferior to the diaphragm and superior to the intestines. It is held into place by several ligaments. Also, sitting in a depression on the posterior surface of the liver is the gallbladder.
 * Sheets of connective tissue divide the liver into thousands of small units called lobules. A lobule is roughly hexagonal in shape, with portal triads at the vertices and a central vein in the middle. The lobule is the structural unit of the liver and rather easy to observe. In contrast, the hepatic acinus is more difficult to visualize, but represents a unit that is of more relevance to hepatic function because it is oriented around the afferent vascular system.
 * The parenchymal cells of the liver are hepatocytes. These polygonal cells are joined to one another in anastomosing plates, with borders that face either the sinusoids or adjacent hepatocytes. The ultrastructure appearance of hepatocytes reflects their function as metabolic superstars, with abundant rough and smooth endoplasmic reticulum, and Golgi membranes. Glycogen granules and vesicles containing very low density lipoproteins are readily observed
 * Hepatocytes make contact with blood in sinusoids, which are distensible vascular channels lined with highly fenestrated endothelial cells and populated with phagocytic Kupffer cells. The space between endothelium and hepatocytes is called the Space of Disse which collects lymph for delivery to lymphatic capillaries.
 * Bile originates as secretions from the basal surface of hepatocytes, which collect in channels called canaliculi. These secretions flow toward the periphery of lobules and into bile ductules and interlobular bile ducts, ultimately collecting in the hepatic duct outside the liver. The hepatic duct is continuous with the common bile duct, which delivers bile into the duodenum. In most species, bile is diverted through the cystic ductinto the gall bladder. The columnar epithelium of the gall bladder is devoted largely to absorption of water and electrolytes.

** Functions: **

 *  Produce Substances That Break Down Fats
 * Produce Substances That Convert Glucose to Glycogen
 * Produce Blood Clotting Substances
 * <span style="font-size: 110%; color: rgb(128, 0, 0);">Produce Bile
 * <span style="font-size: 110%; color: rgb(128, 0, 0);">Converts Ammonia To Urea
 * <span style="font-size: 110%; color: rgb(128, 0, 0);">Make Certain Amino Acids
 * <span style="font-size: 110%; color: rgb(128, 0, 0);">Filter Harmful Substances From The Blood
 * <span style="font-size: 110%; color: rgb(128, 0, 0);">Storage Of Active Immunologic Cells
 * <span style="font-size: 110%; color: rgb(128, 0, 0);">Storage And Release Of Vitamins, Minerals, & Energy
 * <span style="font-size: 110%; color: rgb(128, 0, 0);">Maintain A Proper Level Of Glucose In The Blood

<span style="color: rgb(128, 0, 0);">** <span style="font-size: 110%; color: rgb(128, 0, 0);">Processes By Which Materials Move: ** <span style="font-size: 110%; font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);">
 * <span style="font-size: 110%; font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);"> The liver receives a dual blood supply consisting of 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.
 * <span style="font-size: 110%; font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);">The bile produced in the liver is collected in bile canaliculi, which merge to form bile ducts. Within the liver, these ducts are called //<span style="font-size: 110%; font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);">intrahepatic //<span style="font-size: 110%; font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);"> bile ducts, and once they exit the liver they are considered //<span style="font-size: 110%; font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);">extrahepatic //<span style="font-size: 110%; font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);">. The extrahepatic ducts eventually drain into the right and left hepatic ducts, which in turn merge to form the common hepatic duct. The cystic duct from the gallbladder joins with the common hepatic duct to form the common bile duct. The term "billary tree" is derived from the arboreal branches of the bile ducts. The intrahepatic bile ducts form the most distant branches of this tree. Bile can either drain directly into the duodenum via the common bile duct or be temporarily stored in the glallbladder via the cystic duct. The common bile duct and the pancreatic duct enter the duodenum together at the ampulla of Vater.

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 * **<span style="font-size: 118%; font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);">Alcohol-Induced Liver Disease **<span style="font-size: 118%; font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);"> - caused by excessive consumption of alcohol and is a common, but preventable, disease. Fatty liver is the most common alcohol-induced liver disorder. The liver is enlarged, causing upper abdominal discomfort on the right side.
 * 1) <span style="font-size: 15px; color: rgb(128, 0, 0);">Alcoholic cirrhosis - the destruction of normal liver tissue, leaving non-functioning scar tissue. Symptoms may include those of alcoholic hepatitis, in addition to portal hypertension, enlarged spleen, ascites, kidney failure, confusion, or liver cancer.
 * 2) <span style="font-size: 15px; color: rgb(128, 0, 0);">Alcoholic hepatitis - an acute inflammation of the liver, accompanied by the destruction of individual liver cells and scarring. Symptoms may include fever, jaundice, an increased white blood cell count, an enlarged, tender liver, and spider-like veins in the skin.
 * **<span style="font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);">Autoimmune Hepatitis **<span style="font-family: Arial,Helvetica,sans-serif; color: rgb(128, 0, 0);"> - Hepatitis is the inflammation of the liver, resulting in liver cell damage and destruction. In autoimmune hepatitis, the body's own immune system destroys the cells of the liver. It is a chronic inflammatory liver disease with no known cause.

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 * **<span style="color: rgb(128, 0, 0);">Congenital Liver Defects **<span style="color: rgb(128, 0, 0);"> - Defects of the liver at birth usually affect the bile ducts.
 * 1) <span style="font-size: 110%; color: rgb(128, 0, 0);">Biliary Atresia - a condition in which the bile ducts are absent or have developed abnormally.
 * 2) <span style="font-size: 110%; color: rgb(128, 0, 0);">Choledochal Cyst - a malformation of the hepatic duct that can obstruct flow of bile in infants.

<span style="color: rgb(128, 0, 0); font-family: arial; font-size: 16px; line-height: 20px;">**Works Cited:** <span style="color: rgb(128, 0, 0);">
 * <span style="color: rgb(0, 0, 0); font-family: 'Lucida Grande'; font-size: 12px; font-weight: normal; line-height: normal; white-space: pre;"><span style="color: rgb(128, 0, 0); font-family: Arial; font-size: 14px; line-height: 21px; white-space: normal;">www.vivo.colostate.edu
 * <span style="font-size: 14px; color: rgb(128, 0, 0);">www.healthsystem.virginia.edu
 * <span style="font-size: 14px; color: rgb(128, 0, 0);">www.ehow.com