functions and diseases of liver



Functions of Liver



Important functions of the liver are to metabolize ingested food; to produce amino acids and form proteins; to detoxify ingested medications; to convert nitrogenous substances from the gut into urea and excrete from kidneys; to form clotting factors; to metabolize bilirubin; to process lipids absorbed from the intestine; and to excrete its products as bile.




In addition to these functions, it also stores glycogen and removes bacteria from the blood stream and then traps them. 




The liver has two blood routes: most of blood is supplied by the portal vein from the intestine, and the remainder supplied by the hepatic artery.




After delivered to the liver by the portal vein, blood passes along the hepatic sinusoids in close contact with the hepatocytes and then drains into the hepatic vein.




There are several types of liver cells that include hepatocytes, bile duct cells, and Kupffer cells.



The hepatocytes detoxify, metabolize, and synthesize the digested components.




Bilirubin is made from red blood cells and other hemoproteins by reticuloendothelial cells that are abundant in the liver and spleen.




While bound to albumin, bilirubin is transported to the hepatocytes, solubilized, and then excreted into the bile ducts.




Diseases of Liver



Liver disease may lose hepatocellular activity, resulting in diminishing detoxification, excretory, and synthetic functions.




Diseased hepatocytes or portal hypertension resulting from disruption of portal blood flow through a diseased liver may interrupt bile flow.




Hepatocyte dysfunction decreases production of clotting factors, albumin, and other proteins, as well as endogenously formed lipids.



When hepatocytes are injured due to a variety of causes including viruses, alcohol, autoimmune disorders, and drug hepatotoxicity, cellular enzymes may leak into the systemic circulation.




When hepatocytes are more profoundly injured, coagulopathy, decreased serum albumin, and hyperbilirubinemia may result in. 




When fibrosis occurs in the hepatocyte, the pressure of intrahepatic blood flow from the portal to the systemic venous circulation lowers, resulting in portal hypertension.




Portal hypertension causes abdominal ascites to accumulate and portal-systemic venous collaterals to develop with portal-systemic shunting, resulting in the formation of varices and ultimately in hepatic encephalopathy.  Vascular disorders, including portal vein thrombosis, may also result in portal hypertension.




Since the liver has many functions, complicated blood supply, and intimate relationship with the biliary tree, liver disease can present in a variety of ways.



The cause of presenting complaint may be diffuse, such as acute viral hepatitis with widespread hepatocyte injury as malaise or fatigue, or discrete, such as biliary obstruction from a gallstone in the common bile duct as severe abdominal pain.




Multiple symptoms of patients with liver disease may be nausea and anorexia because of hepatocellular disease accompanied by right upper quadrant discomfort due to stretching of the hepatic capsule by parenchymal cell edema and inflammation.




When liver disease further advances, decompensated cirrhosis may have hepatocellular dysfunction with jaundice and coagulopathy in addition to portal hypertension with ascites and bleeding esophageal varices.




Many patients who present with hepatic symptoms or signs may have non-hepatic disease.  A tender, swollen liver may result from a systemic disorder, such as heart failure with hepatic congestion, rather than a hepatic disorder.



Cirrhotic patients may initially present with a complication such as variceal hemorrhage, which may precipitate hepatic encephalopathy and other features of frank hepatic decompensation.





アルブミン albumin;黄疸 jaundice;肝鬱血 hepatic congestion;肝炎 hepatitis;肝細胞の hepatocellular;肝実質細胞 hepatic parenchyma;肝実質細胞 hepatocyte;肝性脳症 hepatic encephalopathy;肝臓被膜 hepatic capsule;肝類洞 hepatic sinusoid;凝固因子 clotting factor;クッパー細胞 Kupffer cell;グリコーゲン glycogen;グルコース glucose;血液凝固障害 coagulopathy;血栓症 thrombosis;高ビリルビン血症 hyperbilirubinemia;細網内皮細胞 reticuloendothelial cell;静脈瘤 varix:食道静脈瘤 esophageal varix;食欲不振 anorexia;線維症 fibrosis;総胆管 common bile duct;代謝 metabolism;体循環 systemic circulation;胆管系 biliary tree;胆管細胞 bile duct cell;胆石 gallstone;脾臓 spleen;非代償性肝硬変 decompensated cirrhosis;ビリルビン bilirubin;腹水 ascites;浮腫 edema;不定愁訴 malaise;ヘムタンパク質 hemoprotein;門脈 portal vein;門脈圧亢進症 portal hypertension;門脈体循環シャント portal-systemic shunting;門脈体循環静脈副血行路 portal-systemic venous collaterals