Alcohol Flashcards
How is the absolute amount of alcohol calculated
% ABV x 0.78 = g alcohol/100ml (ABV = alcohol by volume)
How are the units of alcohol calculated
%ABV x volume (ml) /1000
What is the equivalent of 1 unit of alcohol
1 unit = 10ml or 8g of absolute alcohol
What is the safe level for men and women (units/week)
less than or equal to 14 units a week
What is binge drinking defined as
More than 8 units in one sitting
18% (>30%)
Describe the dosing of alcohol
0.01% = 10mg/100ml blood
What proportion of alcohol ingested is absorbed in the stomach and small intestine
20% absorbed in the stomach
80% in the small intestine
How does drinking on a full stomach influence your blood alcohol level?
Having a full stomach causes the alcohol to remain in the stomach. This means the alcohol is unable to get to the lining of the stomach for absorption or to the small intestine where it is more effectively absorbed
Speed of onset is correlated to gastric emptying
Describe the metabolic pharmacokinetics of alcohol
85% - liver
First pass hepatic metabolism
15% - GIT
Alcohol -> acetaldehyde -> acetic acid
Which enzymes are involved in the metabolism of alcohol (and in what proportion)
Alcohol dehydrogenase (75%)
Mixed function oxidase (25%)
Aldehyde dehydrogenase for conversion to acetic acid
Explain why the blood alcohol levels in the woman are likely to be higher if she drinks the same as a male
Women do not metabolise alcohol has effectively as they have 50% less alcohol dehydrogenase in the GIT than men
less body water (50% compared to 59%)
Less ADH
Explain why disulfiram can be effective as alcohol aversion therapy
Aldehyde dehydrogenase converts acetaldehyde to acetic acid
Describe the potency of alcohol
Low pharmacological potency (therefore low selectivity)
What are the acute effects of alcohol
CNS
Euphoria
CVS (cutaneous vasodilation)
Diuresis/polyuria
Explain how alcohol causes euphoria
- Opiates/alcohol bind to μ - receptor
- Reduces GABA suppression of the dopaminergic pathway
- VATA -> NAcc
- Dopamine release
Which areas of the CNS does alcohol act one and what are their regular functions
Corpus collosum - rules, logic, impulses, feelings
Hypothalamus - appetite, emotions, temp, pain
Reticular activating system - consciousness
hippocampus - memory
Cerebellum - movements and coordination
Basal ganglia - perception of time
Explain how alcohol causes cutaneous vasodilation
Reduced calcium entry, preventing pre-capillary sphincters from remaining contracted leading relaxation and blood flow through the capillaries
Increased prostaglandins
Explain how alcohol causes an increase in BP
Centrally mediated decrease in baroreceptor sensitivity leads to an acute increase in heart rate and chronic alcohol may be associated with an increased blood pressure
Explain how alcohol causes diuresis
Increase in ADH secretion
Reduces water excretion/increase water retention
Increases feeling of thirst
What are the chronic effects of alcohol
CNS Liver CVS GIT Endocrinological
Explain the chronic CNS effects of alcohol
Thiamine -> enzymes in energy metabolism -> cerebral energy utilisation
Alcohol causes a thiamine deficiency -> impaired brain function
Brain regions with high metabolic demand – impaired metabolism, NMDA excitotoxicity, ROS
What are the chronic CNS effects of alcohol
Dementia Ataxia Wernicke-Korsakoff syndrome Wernicke’s encephalopathy Korsakoff’s psychosis
Explain why dementia and ataxia may be associated with alcohol
Dementia – Cortical atrophy/reduced volume cerebral white matter confusion (encephalopathy), oculomotor symptoms
Ataxia – Cerebellar cortex degeneration - gait
Which areas of the brain are involved in Wernicke-Korsakoff syndrome, Wernicke’s encephalopathy and Korsakoff’s psychosis
Wernicke-Korsakoff syndrome - due to thiamine deficiency
Wernicke’s encephalopathy – hypothalamus/thalamus
Korsakoff’s psychosis – deep brain e.g. hippocampus
Explain the chronic effects of alcohol on the liver
Alcohol requires NAD+ for metabolism, so drinking a lot uses the NAD+ stores in the liver
NAD+ required for other processes in the liver e.g. lipid metabolism (pyruvate to citric acid cycle), ETC
Impairment of liver metabolism
Fat build up
Lipid build up (lipid metabolism interfered with)
Pyruvate converted to lactic acid (acidosis) and ketones (ketosis)
Places a heavy metabolic demand on the liver
Explain how long-term alcohol usage can lead to hepatitis
Blood + Hepatic cytokine changes (e.g. increased IL-6 and TNF-alpha)
Free radicals
Explain how long-term alcohol usage can lead to liver cirrhosis
White blood cells and fibroblasts infiltrate the tissue and lay down connective tissue which eventually replaces the hepatocytes. Hepatocytes decrease and ability to metabolise decreases and toxins build up in the blood.
Cirrhotic liver > liver transplant
What are the beneficial effects of alcohol on the CVS
Reduced mortality from coronary artery disease (Men 2-4 units/day);
Increased HDLs and tPA levels
Reduced platelet aggregation
What are the chronic effects of alcohol on the GIT
Damage to gastric mucose (correlates to dose)
Carcinogenic
What are the chronic effects of alcohol on the endocrine system
Increased ACTH secretion
Decreased testosterone secretion
What are the symptoms of a hangover and explain them
Nausea - irritant -> vagus -> vomiting centre
Headache - vasodialtion
Fatigue - sleep deprivation
Restlessness and muscle tremors
Polyuria and polydipsia - reduced ADH secretion
Explain why individuals may become tolerant to alcohol
Liver upregulation of mixed function oxidase. The same dose of alcohol will be broken down much faster by the liver.
How does alcohol cause increased HR
Depression of baroreceptors which usually inhibits the sympathetic nervous system and stimulates parasympathetic. Sympathetic system becomes dominant and heart rate increases.
