Alcohol Flashcards
how is a unit calculated?
%ABV x volume consumed divide by 1000
1 unit is 8g/10ml absolute alcohol
what is the low risk drinks limit in men and women?
<14 units a week
what is the definition of binge drinking?
> 8 units in one sitting
which two places is alcohol absorbed?
o 20% from the stomach directly.
o 80% from the intestine.
what is alcohol absorption like post-prandial?
stomach does not empty into small intestine during digestion so alcohol is not absorbed well therefore a decreased onset of its effects
what is speed of onset of intoxication proportional to?
gastric emptying
how much alcohol is metabolised?
90% metabolised,
10% breathed off
where is alcohol metabolised?
85% in the liver
15% in the GIT
what is alcohol broken down into?
acetaldehyde (toxic)
what is involved in the breakdown of alcohol in the liver?
75% - Alcohol dehydrogenase.
25% - Mixed function oxidase.
CYP2E1
catalase
aldehyde dehydrogenase
what happens to mixed function oxidase in chronic alcoholics?
upregulated so the alcohol is broken down faster
how does dosage of alcohol affect intoxication?
one high dose will saturate the enzymatic system and lead to higher intoxication than 4 separate lower doses
what is involved in the breakdown of alcohol in the GIT?
100% alcohol dehydrogenase found in the stomach lining
what is the different in alcohol dehydrogenase in men and women?
women have 50% less alcohol dehydrogenase in the GIT
why are women more susceptible to alcohol?
1) women have a lower body water content (50%) compared to men (59%) therefore the alcohol is diluted less in women.
2) Women have greater adipose tissue aswell so alcohol is less well distributed like in men.
3) Men have more alcohol dehydrogenase so metabolise alcohol better
what is acetaldehyde converted to in the liver and GIT?
acetic acid (Acetate) via aldehyde dehydrogenase
what leads to the asian flush?
polymorphism in aldehyde dehydrogenase
what is an inhibitor of aldehyde dehydrogenase?
disulfiram- blocks the enzyme to cause a build up of acetaldehyde
used to put people off alcohol
what is the use of disulfiram?
alcohol aversion therapy as the build up of the toxic acetaldehyde makes you feel sick and not want to drink
why is alcohol considered to have low pharmacological potency?
it is a small, uncomplicated molecule that can bind to many targets generally and not very well therefore a lot of it is required. It has a low efficacy
what is the acute effect of alcohol on the CNS?
depressant effect dependent on environment (social or non-social setting) and the personality of the individual
how does alcohol have a depressant effect on the CNS?
Increasing inhibition – pre- and post-synaptic (via GABA)
Reducing excitation – reducing stimulation at NMDA receptors and reducing Ca2+ influx so less NT exocytosis
but this is difficult to assess in a functionally complex system like the CNS
how does alcohol induce euphoria?
binds to “mu”-receptors to inhibit GABA release. Less GABA means less inhibition on DA release by VTA neurones to the NAcc.
what parts of the brain does alcohol affect?
o Corpus callosum – information from left to right.
o Hypothalamus – controls appetite, emotions, pain, temperature.
o RAS – consciousness.
o Hippocampus – memory.
o Cerebellum – movement & coordination.
o Basal ganglia – perception of time.
how does alcohol cause flushing?
cutaneous vasodilation due to decreased Ca2+ influx so VSM contract less
also increased prostaglandins (vasodilators)
how does alcohol increase heart rate?
diminished control of the brain on arterial baroreceptors so the heart receives reduced inhibitory input
SNS becomes dominant and HR increases