tabacco and alcohol Flashcards
how many deaths per year is tabacco responsible for
5 million deaths/ year
how does smoking affect lifespan?
smokers die on average 10 years younger
cessation at 50 halfs risk
cessation at 30 almost removes added risk
how longs does it take nicoteine to reach brain?
10 seconds from when absorbed into bloodstream
affects are displayed in a few minutes
where are nAch receptors found?
neuromuscular junctions, autonomic ganglia, throughout the CNS
what are the different types of nAch subunits and where are they found?
at neuromuscular junction: alpha1, beta1, gamma, delta and epsilon
at neurone: alpha 2-10 (8 does not exist in humans)
beta 2-4
what type of nAch have been implicated in mediating addictive effects of nicotine ? and how is this shown in mice?
ones with alpha4 and beta2 subunits
mice with deletion of gene for nAch subunit beta2 have reduced self administration of nicotine
where are muscular and neuronal nAchRs located with respect to synapse
muscular: postsynaptic
neuronal: pre and postsynaptic
when nicotine acts on nAchRs what does it cause release of? and what are theyre effects
dopamine noradrenaline GABA and endorphins
dopamine: psychoactive effects
noradrenaline: increased attentiveness
GABA and endorphins: anxiolytic effects (inhibits anxiety)
where is dopamine released after smoking
the mesolimbic dopamine pathway (reward centre)
dopamine releasing cells are in the ventral tegmental area (top of brainstem)
relay pleasure messages to the nucleus accumbens
which then relay messages to cerebral cortex
what are the physiological effects of smoking?
effects on ANS: increases heart rate, blood pressure, sweating and decreased GI motility, release of adrenaline and noradrenaline from adrenal medulla
effects on CNS: symptoms of stimulation and arousal, alleviates stress and anxiety, may enhance learning and sensory performance
relaxation of skeletal muscle (due to effects in spinal cord not NMJ)
what is the tolerance and withdrawal symptoms of nicotine:
tolerance: higher doses required to produce same effect
withdrawal symptoms when stopping: irritability, hunger, restlessness, attentional deficits, sleep disturbances
what is relapse rate in smokers who try to stop?
half of smokers who stop for 6 weeks will relapse within 6 months
20% of smokers who stop for 6 months will relapse within a year
name and describe smoke cessation therapies
nicotine replacement therapy (patches gum etc): relieves withdrawal symptoms, lower concentration than present in smoking, no carcinogens that are present in smoking
bupropion: has been used as an antidepressant, not clear on how it helps smoking cessation, may involve effects on dopamine and noradrenaline transmission
nicotine replacement and bupropion are most cost effective methods
varenicline: partial agonist of alpha4beta2 nAchRs, cause a moderate and sustained increase in mesolimbic dopamine levels
competitive binding with nicotine may reduce rewarding properties of nicotine during relapse
nicotine vaccine (still in development): nicotine conjugated to carrier protien acts as antigen to stimulate antibody production, antibodies against nicotine stop it reaching brain.
how much is a unit of alcohol in pure ethanol?
10mls of pure ethanol
as of 2016 what is the recommended weekly alcohol intake for men and women
do not exceed 14 units/ week for both men and women spread over at least three days
how much does a unit of alcohol raise blood alcohol levels by?
1 unit of alcohol raises blood alcohol by 15mg/100ml
what is rate of alcohol metabolism by body
15mg/100mls of blood per hour, irrespective of blood alcohol concentration
what are the physiological effects of alcohol
alcohol promotes: vasoconstriction, gastric secretion, urine production, liver damage, male impotence
CNS depression, intellectual performance and sensory discrimination impaired.
alcohol stimulates mesolimbic dopamine pathway
what are the positive and negative reinforcements of alcohol
positive: pleasure and happy feelings
negative: relief of stress
how does alcohol cause liver damage?
fatty liver is first stage of liver deterioration in heavy drinkers. Chronic alcohol consumption can lead to accumulation of fatty acids. Accumulation of fatty acids can lead to formation of fibrous scar tissue (fibrosis) which can lead to permanent damage (cirrhosis).
which receptors does alcohol effect?
there is evidence for modulation of functional properties of nAchRs, ATP receptors, 5HT receptors, GABA receptors etc.
how is alcohol absorbed
ethanol is highly lipid soluble, absorbed by stomach and small intestine.
what is the metabolism pathway of alcohol? and what is antabuse
ethanol is converted to ethanal by alcohol dehydrogenase, ethanal is converted into ethanoic acid by aldehyde dehydrogenase. NAD is used as a cofactor in both reactions
Antabuse is a drug which is given to alcoholics which prevents conversion of ethanal to ethanoic acid, build up of ethanal makes them sick whenever they have alcohol.
what is the tolerance and withdrawal symptoms of alcohol
greater quantaties of alcohol are required for same effect since alcohol dehydrogenase is an inducible enzyme.
withdrawal symptoms: tremor, sweating, nausea, hallucinations, confusion.
