1. Liver Structure, Function and Dysfunction Flashcards
What things can cause damage to the liver?
Alcohol Fatty liver disease Viruses Drugs Autoimmune Inherited metabolic syndromes Vascular Chronic biliary disease
How heavy is the average liver?
1.5kg
How regenerative are hepatocytes?
Stable cells
What is the blood supply to the liver?
Hepatic artery and portal vein
What are sinusoids lined with?
Fenestrated epithelium and Kupffer cells
What is the space between sinusoids and hepatocytes known as?
Space of Disse
What type of cell is found in the Space of Disse?
Hepatic Stellate Cells
What is the function of hepatic stellate cells?
Can transform into myofibroblasts if the liver is injured, and can both lay down and digest collagen
What is the venous drainage of the liver?
Hepatic vein
IVC
Right ventricle
What is a portal tract made up of?
Portal vein
Hepatic artery
Bile duct
What cell produces bile?
Hepatocytes
Give the drainage of bile
Cannaliculi between hepatocytes Small ductules Small ducts in portal tracts Left and right hepatic duct join to form common hepatic duct CHD + cystic duct = common bile duct
What are the causes of vascular injury to the liver?
Venous congestion
Obstruction to venous outflow
Ischaemic injury
What is Budd Chiari syndrome?
Thrombus in venous outflow, associated with polycythaemia
What length of time defines chronic liver damage?
> 6 months
What kind of necrosis is seen in small groups of cells?
Spotty necrosis
What kind of necrosis is seen in large groups of cells?
Bridging necrosis
What is the grade in relation to liver damage?
The extent of inflammation and necrosis
What is piecemeal necrosis?
Inflammation is both portal and lobular
What is the stage in relation to liver damage?
How much fibrosis is present
What are the 2 reasons a slide of a liver might be blue
Trichrome stain: collagen
speckly blue= iron= haemochromatosis
What is cirrhosis?
Diffuse distortion of liver architecture
Fibrous bands surround regenerative nodules
Vascular relationships are distorted
What vascular changes take place in cirrhosis?
Obliteration/thrombosis of veins
Shunts form
Sinusoids become capillarised
Increased hepatic venous pressure gradient
What does it mean for sinusoids to become capillarised?
They lose their fenestrations
What initiates portal hypertension?
Increased pressure gradient
What augments portal hypertension?
Splanchnic vasodilation, which increases portal blood flow
What is hyperdynamic circulation?
Splanchnic vasodilation means the rest of the body is getting less blood, so the body compensates to increase CO
What compensation mechanisms are seen in portal hypertension?
RAAS and ADH which increase Na and water retention
Reflex renal vasoconstriction
What are the effects of reflex renal vasoconstriction?
Reduce renal perfusion and GFR
Causes hepatorenal syndrome
What causes acites?
Sodium and water retention
Low albumin due to dysfunctional liver causes leakage from peritoneal vessels
What are shunts?
Fluid tries to find a way around the high pressure in the portal system
Both intrahepatic and extrahepatic
What are the effects of shunts?
Blood bypasses the liver, reducing perfusion and function
porto-systemic anastamoses dilation
What is the difference between compensated and decompensated cirrhosis?
Compensated is a potentially unstable state without symptoms
What are the symptoms of decompensated cirrhosis?
Ascites Hepatic encephalopathy Variceal haemorrhage Hepatorenal syndrome Jaundice Infection Hepatocellular carcinoma
