People and Illness Week 3 Flashcards
(254 cards)
What affect does alcohol consumption have on life expectancy?
Even below recommended limits (<12.5 units/per), alcohol consumption significantly decreases life expectancy
In the UK, how many grams of alcohol constitute a standard ‘unit’ of alcohol?
8g, percentage per litre is the number of units
Describe the trend of estimated deaths due to liver disease compared with the general population
Increasing
How does the risk of injury due to alcohol consumption vary depending on whether it is consumed alone or with meals?
Lower risk of injury if alcohol is consumed with meals
What factors affect the consumption of alcohol by a population?
Economic stability - disposable income
Availability of alcohol - licensing/legality
What is the peak admission age of patients with alcoholic liver disease?
Early/mid 50s
List the risk factors for alcoholic liver disease
The amount, the type and the frequency of alcohol consumption - daily drinking > binge
Alcohol abuse at a young age
Female
Overweight for at least 10 years
Explain the term ‘sick abstainers’
Those who abstain from alcohol who have previously abused alcohol, abstain due to health problems/fear of health problems in the future - makes some data appear as though those who abstain are at higher risk of developing disease, damage is already done in this group
What changes occur in the liver due to chronic excessive alcohol exposure?
Alcohol exposure leads to steatosis in 90-100% of heavy alcohol abusers, which can be reversed by abstinence.
Severe exposure will leads to hepatitis, which can develop from steatosis, hepatitis occurs in 10-35% of heavy alcohol abusers.
Abstinence can reverse hepatitis to steatosis.
Repeated attacks/continued exposure to alcohol can cause cirrhosis to develop from steatosis or hepatitis, which occurs in 8-20% of heavy alcohol abusers.
Describe the structural changes seen in the liver in steatosis
Fatty change
Perivenular fibrosis
Mactosteatosis in zone 2 and 3 - macrovesicular globules of fat
Enlarged liver, yellow colour due to fat accummulation
Describe the structural changes seen in the liver in hepatitis
Liver cell necrosis Inflammation - neutrophils infiltrate Mallory bodies - hyaline Fatty change Swollen hepatocytes Giant mitochondria Steatosis Collagen in zone 3
Describe the structural changes seen in the liver in cirrhosis
Fibrosis
Hyperplastic nodules - micronodular
Irregular nodular appearance
What is the final step in alcohol metabolism?
All processes produce acetaldehyde, which is oxidised to acetate by acetaldehyde dehydrogenase (in the mitochondria)
Describe the pathways involved in alcohol metabolism
Mostly oxidative metabolism in the cytosol by alcohol dehydrogenase
+ Microsomal ethanol oxidising system which uses cytochrome P4502E1 and produces reactive oxygen species
+ Catalase in perioxisomes which produces reactive oxygen species
How is alcohol metabolised in small/moderate amounts?
Oxidative metabolism in the cytosol by alcohol dehydrogenase to acetaldehyde then oxidation to acetate by acetaldehyde dehydrogenase in the mitochondria - other pathways only recruited in alcohol excess
What is the effect of chronic alcohol excess on alcohol metabolism?
Saturates normal pathway, induces recruitment of catalase and cytochrome P4502E1 (MEOS)
Increased production of acetaldehyde, acetate and reactive oxygen species
What are the consequences of alcohol metabolism on the body?
Acetaldehyde production - binds to proteins and DNA (immunogenic), stimulate collagen production by stellate cells
Acetate production - increased acetyl coA promotes inflammation by histone acetylation
Increased NADH/NAD ratio - increased fatty acid synthesis, reduced fatty acid oxidation (promotes steatosis)
Non-oxidative metabolism - fatty acid ethyl ester production (promotes steatosis)
Describe the conversion of NAD to NADH in alcohol metabolism
Cytosol oxidative metabolism -
NAD –> NADH
MEOS -
NADPH –> NADP
Mitochondrial conversion of acetaldehyde to acetate -
NAD –> NADH
What is the net change in NAD/NADH due to alcohol metabolism? What effect does this have?
Increasing NADH:NAD
Increasing NADH drives the electron transport chain - leaks electrons e.g. superoxide ions, hydrogen peroxide ions which are reactive
What produces reactive oxygen species in alcohol metabolism?
Largely through MEOS (especially CYP2E1) but catalase activity may contribute (especially in fasted state)
What are the effects of reactive oxygen species?
Activate redox-sensitive transcription factors such as NF-kapaB which leads to increased TNF-alpha production
Promotes lipid peroxidation which promotes inflammation and damages mitochondral membranes leading to apoptosis
What is the effect of TNF production?
Promotes apoptosis and necrosis, and activates stellate cells to produce collagen leading to fibrosis
What effect does alcohol have on the intestines?
Increases permeability, allows endotoxins to enter the portal circulation - portal circulation endotoxaemia.
This promotes activation of Kupffer cells which in turn promote liver injury - more proinflammatory cytokines (TNF-alpha) and reactive oxygen species.
Describe the changes which occur in hepatocytes following alcohol-related liver injury
Production of reactive oxygen species, activation of NF-kapaB, IL-8 and TNF recruition, neutrophil activation