Liver Anatomy and Physiology Cheat Sheet

Where is the liver? Right upper quadrant What is the liver protected by? Glisson's capsule What divides the liver into right and left lobes? Hepatic portal vein What does the falciform ligament attach To the diaphragm and anterior abdomithe liver to? nal wall How many segments of the liver are there? 8 Where does the hepatic portal vein drain into? GI Tract and spleen Where does the liver get its blood flow from? Hepatic portal vein provides 3/4 of blood flow. Hepatic artery provides 1/4 of blood flow. Like a collection of polyhedral lobules, What does the liver look like under the each possessing a central vein which efmicroscope? ferent blood drains into What are the three triads of blood vessels in the corners of the polyhedral lobules? 1. Portal venule 2. Hepatic arteriole 3. Biliary ductule What does the portal venule do? Carries blood from the portal vein What does the hepatic arteriole do? Brings blood from the hepatic artery What does the biliary ductule do? Transports bile produced from the liver At the polyhedral lobules, afferent blood How does blood get from the liver to the drains from branches of the hepatic porcentral vein? tal vein and hepatic artery into sinusoidal cords which runs into the central vein What carries out the main metabolic functions of the liver? Sinusoidal cords of hepatic cells What are the sinusoids surrounded by? Phagocytic kupffer cells How are sinusoidal cells separated from each other? By plates of hepatocytes What is the space of Disse? Space between the sinusoidal endothelium and hepatocytes 1/8 What does the space of Disse comprise Basement membrane constituents and of? stellate cells which regulate blood flow What do dendritic cells do? Act as antigen presenting cells to lymphocytes What do microvilli do? Increase the hepatocyte surface area What are hepatic triads? Group of vessels from which sinusoids radiate outwards from venues into surrounding lobules What are the functional units of hepatic triads called? Hepatic acinus What zones do hepatocytes fall into? One of the three acinar zones organised by their proximity from the portal venule What is Zone 1 of the three acinar zones? Closest in proximity (to the portal venule). Receives blood rich in nutrients and oxygen making them more resistant to injury. What is Zone 3 of the three acinar zones? Closer the the central venule. Receive less oxygen and nutrients, making them more susceptible to injury. What are the functions of the Zone 1 hepatocytes? Respond readily to changes in glucose or insulin levels and are responsible for glycolysis and gluconeogenesis. Also carry out protein and cholesterol synthesis, beta-oxidation of fatty acids and bile acid secretion. They're responsible for cytochrome What makes Zone 3 more susceptible to P450 activity and NADPH and NADH redrug-induced damage? ductase metabolism. What do bile acids emulsify and why? Dietary lipids in order to improve digestion by pancreatic lipases and enhance absorption of fat-soluble vitamins Where do hepatocytes manufacture bile Water, Bile acids, Cholesterol, Phosphofrom? (5) lipids and Bilirubin. 2/8 Most obtained from distal ileum via portal circulation Which way does bile flow? Opposite direction of efferent blood Where does bile flow to? Biliary ductules situated at the lobule angles How does bile move through the body? Along tightly sealed, protective canaliculi What do cholangiocytes do? Line the intra-hepatic and extra-hepatic biliary tree Where do the ductules drain into? Right or left hepatic ducts (which join to form the common hepatic duct) What does the common hepatic duct join Cystic duct from the gallbladder to form with? the common bile duct Store and concentrate bile. What is the gallbladder's function? And It absorbs 80-90% of water and elechow? trolytes but retaining bile acids and cholesterol What is secreted from the common bile Bile is secreted from the ampulla of Vater duct? into the duodenum Controls the release of bile and prevents What is the sphincter of Oddi responsible bile from being released when digestion for? isn't happening (e.g during fasting). Inserting a tube into the ampulla of the What is Endoscopic Retrograde Cholan- Vater to image and treat obstructive jaungiopancretography (ERCP)? dice caused by condition like pancreatic cancer or gallstones How does the liver make the proteins found in the blood? Using amino acids What does the liver control? Amino acid levels in the blood through processes like gluconeogenesis and transamination What is transamination? Transferring of an amino acid group to from one molecule to another What does albumin do? Maintains plasma oncotic pressure and transports fat soluble drugs and bilirubin 3/8 How much albumin a day does the liver produce? Up to 12 grams a day What is the half-life of albumin? 16-24 days What is hypoalbuminaemia? Low levels of albumin in the blood. Coagulation factors such as fibrinogen (I), Prothrombin (2, 5, 7, 9, 10 and 13) What is reduced in acute liver failure of Antithrombin and Proteins C and S. cirrhosis? (4) What does the reduction of The reduction of the above causes a these things cause? raised Prothrombin Time (PT) and International Normalised Ratio (INR) What is alpha-fetoprotein? Protein present in foetal plasma (lower levels in Down's syndrome ) and in liver carcinoma What is caeruloplasmin? Protein involver in the metabolism of copper. What does transferrin do? Transports iron What does alpha1-antitrypsin do? Limits plasma circulation of important proteases What is alpha1-antitrypsin deficient in? Emphysema What are complement components involved in? The defence against infection and the inflammatory process What does haptoglobin do? Removes aged haemoglobin particles What is 90% of excess nitrogen in the body converted to? Urea What is urea? A waste product secreted in urine Amino acids are broken down into amHow are amino acids converted to urea? monia and then converted into urea in the Urea Cycle. The urea is then excreted How is the urea excreted? renally. What are amino acids degraded to in Krebs-citric acid cycle? Ketoacids for metabolism How much glycogen does the liver store? Approximately 80 grams 4/8 After eating (postprandial), glucose and fructose is absorbed through the porWhat happens to glycogen in a postprantal circulation and stored in the liver dial state? as glycogen preventing hyperglycaemia (high blood sugar) What does glucose-6-phosphate do? Can synthesise fatty acids which is then stores as triglycerides (fat) When not eating, the liver releases its What happens to glucose in the fasting stored glucose from its glycogen via the state? process glycogenolysis (or gluconeogenesis). What is gluconeogenesis? Making glucose from molecules like lactate, pyruvate and amino acids (from muscle tissue) and glycerol (from fat breakdown) Why do fats need lipoproteins? Fats like triglyceride and cholesterol are insoluble in water and need lipoproteins to be transported from the gut and liver to the tissues What does cholesterol do? Ensures cell membranes are fluid and it acts as a precursor for the production of steroid hormones like progesterone, testosterone, oestradiol and cortisol VLDLs (Very Low Density Lipoproteins) What types of lipoproteins does the liver HDLs (High Density lipoproteins) synthesise? LDLs (Low Density Lipoproteins) IDLs (Intermediate Density Lipoproteins) What are IDLs and LDLs derived from? VLDLs What is cholesterol esterified by? Lecithin-cholesterol-aceyltransferase (LCAT) What is cholesterol transferred by? HDLs The enzyme, Lecithin-cholesterol-aceylWhat happens to LCAT in liver disease? transferase (LCAT), is reduced which leads to more free esterified cholesterol 5/8 which can cause red blood cell abnormalities Where are triglycerides formed? In the liver What phospholipid does the liver synthesise? Lecithin Where are bile acids lost? In the faeces What is enterohepatic circulation? Circulation of bile acids from liver to gut and back to the liver Where are bile salts absorbed? They are absorbed freely across the intestinal wall in deconjugated form Where does re-conjugation of bile salts occur? Within the hepatocytes What transports bile salts? And where? Transport proteins move bile salts (and bilirubin diglucoronide) into canaliculi What is the weight of the bile salt pool in the liver? 2.5-5 grams What are the primary bile acids? Cholic acid and Chenodeoxycholic acid How is the solubility of primary bile acids increased? They are secreted in the bile and are conjugated with glycine and taurine What are the secondary bile acids? Deoxycholic acid and Lithocholic acid How are primary bile acids converted to secondary bile acids? Via intestinal bacteria How is bilirubin produced? Breakdown of red blood cells and other haem- containing proteins in the Kupffer cells off the liver (and other parts of the bodies reticuloendothelial system, mainly the spleen) Describe the formation of bilirubin. RBCs break down. Haemoglobin they contained is converted to biliverdin. Then biliverdin is changed to bilirubin whilst the iron and global is reused. 6/8 It binds to albumin in the blood for transport to the liver where it is taken up into How is unconjugated bilirubin transporthepatocytes and conjugated to water soled? uble forms (monoglucuronides and diglucuronides) and excreted in bile What inhibits the transportation of unconjugated bilirubin? Rifampicin, a medication, which can cause increased bilirubin levels as the bilirubin cannot be take to the liver Where is conjugated bilirubin converted? In the gut by bacteria What does conjugated bilirubin turn into? Urobilinogen What happens to urobilinogen? (3) 1. Excreted in stools as stercobilinogen 2. Is reabsorbed, recirculated and re-ecreted by the liver 3. Bound to albumin and excreted renally What does raised urinary bilirubin levels Higher conjugated bilirubin levels and indicate? this points to underlying pathology What are kupffer cells? Phagocytic macrophages in the liver that act upon foreign antigens like bacteria What is the major site for drug metabolism? The liver What does the liver activate? Vitamin D3 by 25-Hydroxylation Describe the metabolism of lipid soluble They're subject to first pass metabolism drugs. so they're affected by hepatic blood flow Where are polar drugs excreted? In bile Where are higher molecular weight drugs excreted? In the biliary system Where are lower molecular weight drugs excreted? Renally What is splenomegaly? Enlarged spleen What is splenomegaly caused by? Portal hypertension What is ascites? What causes it? 7/8 Accumulation of fluid in the abdomen. Caused by liver failure What are 3 symptoms of acute liver failure? - Abdominal pain - Hepatomegaly (enlarged liver) - Dark urine Neurological symptoms like confusion What is portosystemic encephalopathy? and drowsiness that leads to a coma due to decompensated liver failure 8/8