17 - Liver Pathology Flashcards
How much does the liver weigh?
1400-1600 grams
What is the anatomical division of the liver?
Hepatic Lobules
What is the functional division of the liver?
Liver acini (relation to central vein, function and pathology)
Zones and why are they important?
Within acinar structure - periportal/1, mid zonal/2, centrilobular (3)
Important in pathology. Different pathologies may affect different zones,
What are the 5 general responses of the liver to injury/toxic insult?
- Degeneration (loss of hepatocytes) and intra-cellular components - fat-steatosis - occurs with alcohol - and bilirubin-cholestasis - obstruction to biliary flow)
- Necrosis and apoptosis
- Inflammation - acute or chronic hepatitis causing damage to hepatocytes
> especially viral but can be due to autoimmune, drug, alcohol - Fibrosis
> scarring around the regenerating hepatocytes
> progresses on to cirrhosis - Regeneration and proliferation of hepatocytes
> trying to repair damage liver
What is the most common cause of liver injury we will see?
Viral infection and drug/toxin affects especially alcohol
What is hepatic failure?
When there is sudden and massive damage to the liver or is the end point of chronic damage resulting in 80-90% loss of liver capacity/function. The threshold for liver failure to present is so high because of the large hepatic reserve/regenerative capacity
Where do you see liver failure most commonly?
Viral hepatitis - massive lost of hepatocytes and so liver function
What is an example of chronic damage to the liver?
Chronic injury due to chronic alcohol intake - lost hepatic reserve and present with hepatic failure
What dose it mean to say often in hepatic failure there is decompensation associated with increased demand?
Often patients are on the boderline of hepatic function/don’t have any hepatic reserve but cope fine. If an injury or event occurs such as bleeding, or infection, that requires an increase demand/function, this can tip the patient into over into hepatic failure as they have no hepatic reserve
hepatic failure has a … mortality
high
What are 3 clinical features of hepatic failure?
- jaundice
- hypoalbuminaemia (less albumin/clotting factor - loss of synthetic function)
- elevated ammonia leading to neurological dysfunction (due to a decrease in protein breakdown/metabolic activity and detoxification by the liver)
Describe hepatocellular necrosis
- may see in panadol overdose
- necrosis to hepatocytes near hepatic vein/portal triad i.e. periportal/zone 1
What are some characteristics of cirrhosis?
- there is bridging of fibrous septa that often links portal tracts
- parenchymal nodules (micro and macronodules) of proliferating hepatocytes encircled by fibrosis
- disruption of liver and vasculature architecture disrupting function
> vasculature interupted and increased pressure causes formation of shunts and reversal of blood flow from hepatocytes and portal vein
What is portal hypertension?
Where there is increased resistance to portal blood flow i.e. fibrosis/cirrhosis and interuption of vasculature resulting in increased pressure and backflow/shunting of the portal system to the systemic system
What may cause increased pressure in the portal system/vein?
- prehepatic
> obstruct before portal vein enters liver
> obstructive thrombosis in the portal vein
> often see in coagulation problems - post hepatic
> obstruction after the liver
> SEVERE right side heart failure where there is increased pressure at the RA and so IVC and eventually portal vein - intrahepatic (most common)
> within the liver
> cirrhosis which causes a fibrosis and distortion of the vasculature causing and increasing the pressure of the hepatic vessels
Most common cause of portal hypertension?
Hepatic causes especially cirrhosis
What are 4 consequences of portal hypertension?
- Ascites
- Porto-systemic shunts
- Congestive splenomegaly
- Hepatic encephalopathy
Prehepatic causes of portal hypertension?
> obstruct before portal vein enters liver
obstructive thrombosis in the portal vein
often see in coagulation problems
Post hepatic causes of portal hypertension
> obstruction after the liver
> SEVERE right side heart failure where there is increased pressure at the RA and so IVC and eventually portal vein
Intra hepatic causes of portal hypertension
> within the liver
cirrhosis which causes a fibrosis and distortion of the vasculature causing and increasing the pressure of the hepatic vessels
Congestive splenomegaly?
Pressure increase in portal vein so backflow into splenic vein = splenic congestion and enlargement of the spleen
hepatic encephalopathy?
Shunting of hepatocytes so not normal metablic functions. Ammonia to brain.
Causes of viral hepatitis?
Hepatitis A,B,C,D,E viruses
Cytomegalovirus (CMV)
Epstein-Barr virus
> i.e. many viruses will cause hepatic inflamation
