alcohol

Question 1

describe how you calculate the absolute amount of alcohol (g alcohol/100ml)

Answer 1

%ABV x 0.78

Question 2

how do you calculate units?

Answer 2

(%ABV x volume/ml)/1000

1 unit = 10mls or 8g of absolute alcohol

Question 3

how many units should people drink? what is classified as binge drinking?

Answer 3

< 14 units/week

binge drinking = >8 units in one sitting

Question 4

describe the 2 locations of absorption of alcohol

Answer 4

20% from stomach directly

80% from intestines

Question 5

what is the speeds of onset of intoxication proportional to?

Answer 5

• proportional to gastric emptying
• post prandial, stomach does not empty as often as it needs to break down food
• so alcohol is not absorbed very well

Question 6

describe the metabolism of alcohol

Answer 6

• only 90% is metabolised
• 10% breathed off
• 8% of metabolism occurs in liver
• 15% occurs in GIT

Question 7

describe the liver metabolism of alcohol

Answer 7

• alcohol to acetaldehyde (toxic) via alcohol dehydrogenase (75%) and mixed fucntion oxidase (25%)
• MFO most significantly up regulated in chronic alcoholics

Question 8

what is the difference in 1 high dose bolus of alcohol compared to same absolute amount of alcohol over 4 separate doses?

Answer 8

• one high dose bolus will saturate enzymatic system leads to higher intoxication

Question 9

describe the GIT metabolism of alcohol

Answer 9

• alcohol –> acetaldehyde via alcohol dehydrogenase found in stomach
• females have less ADH than males in GIT

Question 10

why are women more susceptible to alcohol?

Answer 10

men have more body water. more ADH = more body water

more water also allows alcohol to be more widely distributed

Question 11

what happens next to acetaldehyde in liver and GIT metabolism?

Answer 11

acetaldehyde –> acetic acid via aldehyde dehydrogenase

polymorphisms can be found in this enzyme leads to asian flush

Question 12

what is disulfiram?

Answer 12

inhibitor of aldehyde dehydrogenase

effective in alcohol aversion therapy as build up of acetaldehyde makes you feel sick and not want to drink

Question 13

describe the general pharmacodynamicsof alcohol?

Answer 13

• low potency
• influences a lot of receptors as it has an uncompiicated shape
• but doesn’t fit a lot of receptors very well so not a lot of efficacy

Question 14

what are the acute effects of alcohol on the CNS?

Answer 14

• depressant effect
• alcohol depresses system by: inc. inhibition, reducing excitation (reducing stimulation at NMDA receptors and reducing Ca influx so less NT exocytosis)

Question 15

how does alcohol cause CNS euphoria?

Answer 15

• alcohol binds to mu-receptor to inhibit GABA release

- less inhibitory GABA means less inhibition on DA release by VTA DA neurones into NAcc

Question 16

what parts of the brain does alcohol affect?

Answer 16

• corpus callosum
• hypothalamus (appetite, emotions, pain, temp)
• RAS (consciousness)
• Hippocampus (memory)
• cerebellum (movement and coordination)
• basal ganglia (perception of time)

Question 17

what are the acute effects of alcohol on the CVS?

Answer 17

• cutaneous vasodilation = flushing (dec. Ca influx –> less VSM contraction, inc. prostaglandins –> vasodilators)
• inc. HR (SNS becomes dominant and HR inc, alcohol diminishes control of brain on arterial baroreceptors so heart receives less inhibitory input)

Question 18

what is the endocrine effects of alcohol?

Answer 18

• alcohol dehydrogenase supresses VP release

- Less VP and less water reabsorption = diuresis

Question 19

what are the chronic effects of alcohol on CNS?

Answer 19

• dementia - cortical atrophy and dec. cerebral white matter
• ataxia - cerebellar cortex degeneration
• Wernicke-Korsakoff’s syndrome - due to thiamine def as less food intake as calories from alcohol

Question 20

what are the 2 parts of Wernicke-Korsakoff’s syndrome?

Answer 20

• Wernicke’s encephalopathy (affects 3rd ventricle and aqueduct)
• Korsakoff’s psychosis (affects dorsomedial thalamus, irreversible, impairs memory)

Question 21

what are the chronic effects on the liver, regarding NAD+?

Answer 21

• need NAD+ for a lot of functions
• alcohol dominates the use of NAD+
• so NAD+ is not used for other functions
• leads to build up of other dangerous toxic by-products

Question 22

what causes fatty liver?

Answer 22

lack of NAD+ means that the TAGs are deposited in liver

Question 23

what causes hepatitis?

Answer 23

• mixed function oxidases unregulated in chronic alcoholics
• generate free radicals which generate an inflammatory response
• cytokines released e.g. IL-6, TNF-alpha

Question 24

what causes cirrhosis?

Answer 24

• fibroblasts lay down fibrin supportive structures
• reduce regenerative capacity of liver
• dec. regeneration and active liver tissue
• inc. fibroblasts

Question 25

what are the positive effects on the CVS?

Answer 25

• dec. mortality from coronary HD
• inc. HDLs
• inc. tPA levels –> dec. platelet aggregation levels
• polyphenols (red wine) may reduce free radicals

Question 26

what are the GIT chronic effects of alcohol?

Answer 26

• damages gastric mucosa
• can lead to stomach cancer from acetaldehyde build up
• acetaldehyde is carcinogenic

Question 27

what are the endocrine chronic effects of alcohol?

Answer 27

• inc. ACTH secretion –> Cushing’s ike syndrome

- dec. testosterone –> gynecomastia

Question 28

what are the symptoms of a hangover? what causes them?

Answer 28

symptoms peak as BAC approaches 0

• nausea: irritant –> vagus –> vomiting centre of medulla
• headache: vasodilation
• fatigue: sleep deprivation
• restlessness: rebound excitation as BAC –> )
• polyuria, polydipsia (dec. VP secretion)