Alcoholism Flashcards
What are the primary neurotransmitters of the brain?
GABA -inhibitory
Glutamate - stimulatory
What are the secondary neurotransmitters?
Dopamine Serotonin Noradrenaline ACh Endogenous opiods These add tone, valence and emotion to the primary process
How do full agonist opiates work? (E.g. Heroin)
Act on the neurotransmitter pathway, but with a much greater effect than the natural transmitter
- the drug hijacks the natural transmitter system
- normal levels of stimulation are now not enough in comparison = addiction
How does alcohol cause addiction?
It indirectly stimulates the endogenous opiate system
- enhances the action of the inhibitory neurotransmitter GABA
This enters the synaptic cleft and binds to its receptors, opening chloride channels and hyperpolarising the membrane, lowering cell excitability
Some drugs work by acting on dopamine, how do they do this?
Stimulant drugs increase energy and stamina by increasing synaptic levels of dopamine
Some drugs increase dopamine availability in other brain regions; nucleus accumbens and prefrontal cortex
Normally the reward circuit in the brain is activated by food, water and sex
- drug abuse produces a greater effect on the reward system, and so the brain directs normal drives away from the natural reinforces and towards the drug
Define alcohol dependence?
An individual is physically or psychologically dependent on drinking alcohol - access to alcohol is the thing that takes on greatest value in their life
What criteria must someone fit to be diagnosed as alcohol dependent?
3 out of the 7 following things
- tolerance
- withdrawal symptoms
- used in larger amounts or for longer periods than intended
- persistent desire or unsuccessful efforts to cut down
- time is spent obtaining alcohol
- social, occupational and recreational pursuits are given up or reduced due to alcohol use
- use is continued despite knowledge of alcohol related harm
What is the difference between dependence and abuse?
Dependence includes tolerance and withdrawal
Abuse can still include binge drinking
What is tolerance?
Reduced sensitivity requires that higher quantities of alcohol must be consumed in order to reach the same effects as before tolerance was established
What is reverse tolerance?
A liver damaged by chronic alcohol use, builds up fat and scar tissue
This reduces the ability of the liver to metabolise or break down alcohol and small amounts can lead to high blood alcohol concentrations
What does a persons alcohol tolerance depend on?
Activity of alcohol dehydrogenase - found in the liver and in the blood
What is a unit of alcohol?
10ml or 8g of pure alcohol
- equates the amount the average adult can process in one hour
What are the normal alcohol limits?
Advised not to drink more than 14 units a week, and should be spread out over a few days
- should include some days of abstinence
What substance is most alcohol metabolised to?
Acetaldehyde
- a highly reactive and toxic substance
- responsible for physical damage caused by excessive alcohol consumption
What is acetaldehyde metabolised to?
Acetate
- non toxic and concentrations in tissues is low
What is produced during oxidation of excess alcohol?
Lactic acid Keto acid Retention of uric acid Hyperlipidaemia Accumulation of fat in the liver
What are the two pathways of alcohol metabolism?
Cytoplasmic alcohol dehydrogenase (CDH)
Microsomal ethanol oxidising system (MEOS)
Describe the cytoplasmic alcohol dehydrogenase system
It is the main, non-inducible route.
Alcohol is metabolised to acetaldehyde by alcohol dehydrogenase in the cytosol of cells
Acetaldehyde is then oxidised to acetate by acetaldehyde dehydrogenase in the mitochondria
Describe the Microsomal ethanol oxidising system
This is an inducible system, and takes excess alcohol the CAD system can’t handle
Alcohol is oxidised in acetaldehyde by the action of CYP2E1 in the SER
This reaction gives of a ROS as a byproduct
Then, acetaldehyde is oxidised to acetate in the mitochondria by the action of acetaldehyde dehydrogenase
Describe the acute physical injuries associated with drinking alcohol.
Accident and injuries Acute alcohol poisoning Aspiration pneumonia Oesphagitis Malory-Weiss syndrome Gastritis Pancreatitis Cardiac abnormalities Cerebrovascular accidents Neuropraxia Myopathy
List the chronic problems that can arise from alcohol abuse.
Accidents and injuries Oesphagitis Gastritis Malabsorption Pancreatitis Malnutrition Liver damage Systemic hypertension Cardiomyopathy Coronary heart disease Cerebrovascular accidents Brain damage Peripheral neuropathy Osteoporosis - alcohol directly onto bone reduces bone mass Skin disorders Malignancy Sexual dysfunction Foetal damage
Describe the relationship between alcohol and chronic pancreatitis.
Alcohol use can cause progressive and irreversible damage to the pancreas gland
Pancreatic calcification and gland distortion
Main clinical features are pain coupled with malabsorption/maldigestion and diabetes - main problem is continuous epigastric pain