Alcohol Flashcards
How would you work out the absolute amount of alcohol consumed?
%ABV x 0.78
How many units is considered binge drinking in the uk?
> 8 units in one sitting
How much of alcohol is absorbed from what different parts of the body?
20% from the stomach directly
80% from the intestine
What is the speed of onset of intoxication proportional to?
Gastric emptying
Why does eating a meal decreases the speed of onset of alcohol?
Postprandial, the stomach does not empty often as it needs to break down food thus alcohol is not absorbed very well
How is alcohol metabolised?
90% is metabolised, 10% breathed off. 85% of metabolism occurs in the liver, 15% occurs in the GIT.
Liver metabolism: alcohol -> adetaldehyde (toxic) via 75% alcohol dehydrogenase and 25% mixed function oxidase.
Which type of enzyme is most significantly upregulated in chronic alcoholics?
Mixed function oxidase
Why does a shot of alcohol affect you more than the same amount of alcohol in 4 seperate doses
Because a single high dose alcohol bolus will saturate the enzymatic system
Why are women more susceptible to alcohol?
Men have a greater volume of body water and women have more adipose tissue, so the water allows alcohol to be more widely distributed in men so at a lower concentration -> men have more ADH as well so more able to metabolise
What is disulfiram and what is it used for? How does it work?
It is an inhibitor of aldehyde dehydrogenase - effective in alcohol aversion therapy as build up of acetaldehyde makes you feel sick and not want to drink alcohol
What is the potency of alcohol? Why?
Low
Influences a lot of receptors due to its uncomplicated shape however doesn’t fit a lot of the receptors very well so not a lot of efficacy
What effect does alcohol have on the CNS (mainly)
Depressant effect mainly - dependent upon environment and personality of the individual
How does alcohol depress the CNS system?
Increasing inhibition - pre and post synaptic
Reducing excitation - reducing stimulation at NMDA receptors and reducing Ca2+ influx so less NT exocytosis
Why is it difficult to assess the acute CNS effects of alcohol?
CNS is functionally complex
Ethanol has low potency therefore low selectivity
How does alcohol have euphoric effects on the CNS
Alcohol binds to the u receptor to inhibit GABA release - less inhib GABA so less inhib on DA release by the VTA DA neurones into the NAcc
What parts of the brain does alcohol affect?
- Corpus callosum – information from leftàright.
- Hypothalamus – controls appetite, emotions, pain, temperature.
- RAS – consciousness.
- Hippocampus – memory.
- Cerebellum – movement & coordination.
- Basal ganglia – perception of time.
What are the acute effects of alcohol on the CVS?
Vasodilation and increased HR
What are the acute effects of alcohol on the endocrine system?
Diuresis (polyuria)
How does alcohol cause vasodilation?
Cutaneous vasodilation - flushing by decreased Ca2+ influx so less VSM contraction leading to increased prostaglandins (vasodilators)
How does alcohol increase heart rate?
Alcohol diminishes the control of the brain on the arterial baroreceptors and so the heart recieves less inhibitory input
-> SNS becomes dominant and heart rate increases
How does alcohol cause diuresis (polyuria)
ADH (alcohol dehydrogenase) supresses VP release and less VP release leads to less water reabsorption causing diuresis
What are chronic effects of alcohol on the CNS?
Dementia
Ataxia
Wernicke-korsakoff’s syndrome
What happens to the brain in dementia?
Cortical atrophy and decreased cerebral white matter
What happens to the brain in ataxia?
Cerebellar cortex degeneration
What happens to the brain in wernicke-korsakoff’s syndrome?
Wernicke’s encephalopathy - affects the 3rd ventricle and aqueduct REVERSIBLE
Korsakoff’s psychosis - affects the dorsomedial thalamus (impairs memory - they make memories up) IRREVERSIBLE
What is Wernicke-korsakoff’s syndrome due to?
Due to thiamine deficiency (less food intake as calories from alcohol)
What are the chronic effects on the liver due to alcohol due to?
NAD+:
NAD+ is needed for lots of functions, alcohol dominates the use of NAD+ and thus NAD+ is not used for the other functions leading to a build up of other dangerous toxic by-products
What are examples of chronic effects of alcohol on the liver?
Fatty liver
Hepatitis
Cirrhosis
What is fatty liver in alcohol toxicity due to?
Lack of NAD+ leading to TAGs deposited in the liver
What is hepatitis in alcohol toxicity due to?
Mixed function oxidases upregulated in chronic alcoholics leading to free radicals that generate an inflammatory response
Cytokines are then released eg increased IL-6 and TNF alpha
What is cirrhosis in alcohol toxicity due to?
Fibroblasts lay down fibrin supportive structures that reduce regenerative capacity of liver - decreased regeneration and active liver tissue, increased fibroblasts
What are positive effects of alcohol on the CVS?
- decreased mortality from coronary heart disease
- increased HDLs
- increased tPA levels -> decreased platelet aggregation levels
- polyphenols (red wine) may reduce free radicals
What are the chronic effects of alcohol to the GIT?
Damages gastric mucosa (in proportion to the dose)
- can lead to stomach cancer from acetaldehyde build up
- acetaldehyde is a carcinogenic
What are the chronic effects of alcohol on the endocrine?
Increased ACTH secretion -> cushing’s like syndrome
Decreased testosterone -> gynecomastia
What are examples of symptoms as the blood alcohol concentration reaches 0
- nausea
- headache
- fatigue
- restless and muscle tremours
- polyuria, polydipsia
Why do you get nausea in a hangover?
Irritant -> vagus -> vomiting centre of medulla
Why do you get headaches in a hangover?
Vasodilation
Why do you get fatigues in hangover?
Sleep deprivation ‘rebound’
Why do you get restlessness and muscle tremors in a hangover?
‘rebound’ excitation
What do you get polyuria and polydipsia in a hangover?
Decreased VP secretion
