L24 - Liver Anatomy

• Descibe the anatomy of the liver- where is it?- how many lobes? etc

  - under diaphragm- functionally, two lobes - Left and Right- anatomically, 4 lobes: L, R, caudate and quadrate- apex, falciform ligament, round ligament

  
• What are the exocrine functions of the liver? (digestion?)

  Forms bile salts for digestion and absorption of fats
• What is bile?- where is it formed?

  bicarbonate-rich solution (HCO3-) which neutralises HCl in duodenum- formed in liver, stored in gallbladder
• What are then endocrine functions of the liver? (hormonal)

  secretes insulin-like growth factor
• What's the role of the liver in the coagulation cascade?

  Produces clotting factors, eg pro-thrombin and fibrinogen

  
• Why can liver dysfunction lead to bleeding disorders?

  Bc the liver synthesises clotting factors eg pro-thrombin and fibrinogen (Thrombin cleaves fibrinogen into fibrin).If liver malfunctions and can't produce clotting factors, then
• What do statins target in the liver?

  = cholesterol synthesis- cholesterol is synthesised and metabolised in the liver, then converted into bile.
• What does the liver metabolise?

  drugs, carbohydrates, proteins, fats etc.
• What are the excretory/degradation functions of the liver?

  - secretes bile pigments into bile and destroys erythrocytes
• What is hepatostat?Why important?What happens to liver in pregnancy/with severe weightloss?

  = adjustment of liver size- liver has unique regenerating capacity- maintains good ratio of liver with bodyweight in proportion to body's needs- pregnancy: size increases- weight loss: size decreases
• What are the two surfaces of the liver?

  Diaphragmatic - dome facing up to diaphragm. Smooth.Visceral - "upside down". Faces abdominal organs. Ridges accommodate gallbladder, biliary ducts. Porta hepatis here.

  
• What is the porta hepatis?Where is it?

  Collection of blood vessels (hepatic arteris/veins) and bile ducts.On visceral surface of liver.

  
• What are the two main ligaments called? Where are they?

  Falciform ligament: separates major right and left lobes. Attaches liver to diaphragm and anterior abdominal wallRound ligament:Lower edge of falciform ligament
• Gallbladder- what does it do?- where is it?- what does it look like?

  - accessory organ that stores and concentrates bile produced in liver- on visceral surface of liver- fundus = wide end. Neck = narrow, tapered, S bend into cystic duct.Internal spiral fold of mucosa helps keep duct open to prevent blockages

  
• Where does the liver receive blood from?

  1. Oxygenated blood from heart via hepatic artery2. Deoxygenated blood from GI tract (small intestine) via hepatic portal vein

  
• What happens to blood in the liver?

  Sources of ox/deox. blood from heart/GI tract mix and drain into the central vein before returning to heart via inferior vena cava
• What's the functional unit of the liver called?

  Liver lobules/ hepatic lobules
• What are the main cells found in liver?

  - hepatocytesand stellate, kupffer, endothelial, cholangiocytes etc

  
• What do endothelial cells do?

  line blood vessels (single layer)

  
• What makes up a portal triad?

  hepatic artery, hepatic portal vein, bile duct

  
• How does blood flow in liver?

  - blood flows into hepatic lobules from edge via hepatic portal vein and hepatic artery through portal triads- drains into central vein- central vein empties into hepatic veins, then to inferior vena cava

  
• How does bile flow in the liver?

  - in opposite direction to blood: counter-current flow- down bile canaliculi towards portal triad where it flows into bile ductules- transported from bile ductules to GI tract/gallbladder

  
• What is a polarised cell?What kind of liver cell is polarised and why?

  different on different surfaces - apical surface and basolateral surfaceHepatocyte - one side forms bile duct, the other faces another hepatocyte

  
• What is a bile duct made from?

  Hepatocytes (bc polarised cells!) APICAL surfaces form bile ducts.(Basolateral surfaces face other hepatocytes/sinusoids)

  
• What are sinusoids?

  Fenestrated capillaries with large lumens in liver

  
• Hepatocytes- what are they?- what do they do?- which way do their membranes face?

  = Polarised cells of the liver- separate sinusoidal blood from canalicular bileBasolateral membrane: faces sinusoidal endothelial cells/other hepatocytesApical membrane : faces bile canuliculi

  
• What does bile contain?

  HCO3-, cholesterol, lecithin (phospholipid), bile pigments and bile salts
• What do we mean by fenestrated epithelial cells?

  gaps in endothelial cellsminimises barriers for substance transfer
• What is a space of Disse?

  anatomical gap between endothelial cells and hepatocytes
• What do fenestrated epithelial cells do?

  - filter between lumen of hepatic sinusoids and hepatocytes- minimise barrier for substance transfer
• What are liver sieve plates?

  aggregrated fenestrations - a collection of gaps between endothelial cells
• Kupffer cells- where are they?- function?- why more tolerant?

  - tissue macrophages in liver (aka stellate macrophages)- lumen of sinusoids- host defence: liver is first point where blood from GI tract flows into body- more tolerant to pathogens so less likely to cause inflammatory response to prevent hepatitis

  
• What is hepatitis?

  Inflammation of the liver
• Stellate cells- where found?- what are they involved in?

  - in subendothelial space between basolateral surface of hepatocytes and anti-luminal side of sinusoidal endothelial cells?- surrounds more than 2 nearby sinusoids- involved in liver fibrosis

  
• What are cholangiocytes?What do they do?

  - epithelial cells that line intra/extrahepatic bile ducts- modify bile to generate ductal bile
• What does the cystic duct connect?

  Connects the neck of the gallbladder to the common hepatic duct
• Sphincter of Oddi- location?- function?

  - where common bile duct meets small intestine- controls bile entry into small intestine from gallbladder/liver

  
• Bile Duct Anatomy- intra/extrahepatic bile ductsDescribe bile duct anatomy including from liver and gallbladder into small intestine- what are cholangiocytes?


  - intrahepatic ducts span both lobes- extrahepatic: first part = common hepatic duct or hilum region, where R and L ducts come together- cystic duct = S bend from gallbladder w/ spiral folds inside. Connects gallbladder to common hepatic duct- common bile duct: 'distal' region goes into small intestine-cholangiocytes = epithelial cells lining intra/extrahepatic ducts of biliary tree