PBL 2 Flashcards
what’s the commonest cause of chronic liver disease?
alcohol
whats more of a risk factor for liver disease, binge drinking or daily drinking?
daily drinking
whos more likely to get liver disease, men or women?
women are more likely to get more severe disease e.g. alcoholic liver disease
men are more likely to die from cirrhosis
what are the 3 stages of alcoholic liver disease?
alcoholic fatty liver (steatosis)
alcoholic hepatitis (steatohepatitis)
cirrhosis
outline the pathophysiology of alcoholic steatosis?
alcohol enters hepatocytes
Alcohol dehydrogenase converts alcohol to acetaldehyde and acetaldehyde dehydrogenase converts acetaldehyde to acetate. Both of these mechanisms work by also converting NAD+ to NADH; as NADH levels increase, the cell starts to produce more fatty acids and lower NAD+ levels result in less fatty acid oxidation.
acetaldehyde also promotes production of enzymes involved in fatty acid synthesis and inhibits enzymes involved with fat oxidation. Both of these lead to more fat production in the liver (fatty change / steatosis).
what pathway does chronic alcohol use up-regulate?
whats the effect of this?
which patients is this effect exaggerated in?
the CYP450 2E1 pathway (enzyme involved in ethanol metabolism)
this produces harmful reactive oxygen species which damage protein and DNA
this effect is exaggerated in patients with deficient antioxidants e.g. those who are malnourished
outline the pathophysiology of alcoholic steatohepatitis?
Chronic alcohol exposure activates hepatic macrophages, triggering inflammation
Acetaldehyde can also bind to cellular proteins of the hepatocyte (acetaldehyde adducts). The immune system recognises these as foreign so neutrophils destroy hepatocytes - promoting inflammation.
As cells become inflamed and damaged, it is now referred to as steatohepatitis.
what would you see on histology at alcoholic steatohepatitis stage?
mallory bodies (cytoplasmic hyaline inclusions of hepatocytes)
what would be the symptoms at alcohol steatosis stage?
mostly asymptomatic
how would alcoholic steatohepatitis present?
painful hepatomegaly neutrophil leukocytosis ALT and AST levels raised ALP and GGT elevated thrombocytopenia hypoglycaemia
what is ALT?
alanine transaminase
liver enzyme released into the blood when hepatocytes are damaged
what is AST?
aspartate aminotransferase
liver enzyme released into the blood when hepatocytes are damaged
what is ALP?
Alkaline phosphatase
an enzyme made in liver cells
what is GGT?
gamma-glutamyl transferase
mostly found in the liver
outline the cirrhosis stage of alcoholic hepatitis?
◦ chronic inflammation and subsequent attempts at tissue repair lead to formation of scar tissue. As a result the livers internal structure is disrupted, impairing its functions.
why does cirrhosis cause portal hypertension?
When an obstruction (in this case fibrous tissue) prevents blood flow, venous blood accumulates in the portal system and pressure rises >12mmHg
why can cirrhosis cause hepatic encephalopathy?
As liver functions decline, toxins can build up and reach the general circulation and pass into the brain producing symptoms such as confusion, drowsiness, tremor or even coma
whats the treatment for alcoholic hepatitis?
abstinence
corticosteroids to suppress the immune system
liver transplantation
what is the portal venous system?
the vessels involved in the drainage of the GI tract and spleen into the liver
portal vein, splenic vein and mesenteric vein
what are the 3 connections between the portal venous system and systemic venous system?
oesophagus
superior portion of anal canal
round ligament of liver
what are portosystemic shunts?
when blood is diverted away from the portal system and backs up into systemic veins
Portal hypertension causes less blood to reach the liver. What is the effect of this?
decreased liver function and blood detoxification (presents as jaundice). Build up of toxic metabolites in the blood that can cause hepatic encephalopathy
whats the effect of portosystemic shunts caused by portal hypertension?
oesophageal varices which can rupture and cause haematemesis
haemorrhoids in the rectum which can bleed and present as melena or Hematochezia
caput medusae
what is caput medusae?
a cluster of swollen veins in your abdomen