Metabolism of Alcohol Flashcards by Ethan Thrower

What are the harmful agents in alcohol?

Ethanol
Methanol - from poorly distilled alcohol
Isopropyl alcohol

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What does the liver oxidise alcohol into?

Oxidises alcohol into water, carbon dioxide, and energy.

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What is 1 unit of alcohol?

8grams of alcohol

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What are considered the healthy number of units for men per week?

28 units per week

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What are considered the healthy number of units for women per week?

21 units per week

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How does high concentration alcohol affect the stomach?

Inhibits gastric emptying - therefore has a slow absorption.

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How can alcohol absorption be increased by drug consumption.

Increased by drugs enhancing gastric emptying and

those drugs that inhibit gastric alcohol dehydrogenase

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Most tissues (e.g. heart, brain and muscles) are
exposed to the same concentration of alcohol as
the blood - why is the exposure to the liver greater?

Exposure of the liver is greater because blood is
received direct from the small bowel via the portal
vein.

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What physiologic changes accompany alcohol consumption.

Sweating, flushing (dilation of blood vessels) and
bruising.
Body can suffer from heat loss and hypothermia.
Tachycardia and hypertension.
Kidneys secrete more alcohol due to both fluid and alcohol inhibiting ADH.

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How is absorbed alcohol eliminated?

95% metabolised by the liver.
2-5% is excreted unchanged in urine, sweat,
faeces, milk or breath.

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What enzymes break down alcohol in the liver?

Alcohol dehydrogenase (ADH) and mitochondrial acetaldehyde dehydrogenase (ALDH) metabolise ethanol consumed.

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What is the first step in the metabolism of alcohol?

- draw it out.

The first step in the metabolism of alcohol is the oxidation of ethanol to acetaldehyde catalyzed by ADH (in the cytosol) containing the coenzyme NAD+.

Results in the generation of NADH.

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What is the toxic byproduct produced in the metabolism of alcohol?

Acetaldehyde

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What is the second step in the metabolism of alcohol?

- draw it out.

Conversion to acetaldehyde into acetate by ALDH (in

mitochondria) also results in the generation of NADH

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What does the enzyme alcohol dehydrogenase do?

The enzyme alcohol dehydrogenase (ADH) metabolizes the ethanol into toxic acetaldehyde.

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What is the third step in the metabolism of alcohol?

- draw it out.

The acetate is further oxidized (mitochondrial extrahepatic oxidation) to CO2 and water through the citric acid cycle.

The acetate entering the citric acid cycle generates even more NADH.

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Explain how alcohol tolerance is built up?

Enzyme induction -
The liver does this by producing larger amounts of the enzymes which break down alcohol.
The brain also has a role in the development of alcohol tolerance. When the neurotransmitter systems in the brain are regularly exposed to large amounts of alcohol they begin to adapt to the presence of alcohol.

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What are the short term metabolic risks of alcohol?

Block other metabolic pathways in high concentrations.

Converts pyruvic acid to lactic acid - can lead to acidosis.

Inhibits gluconeogenesis which can lead to hypoglycemia.

Inhibits lipolysis and increases lipogenesis.

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What by byproduct of ethanol is responsible for blocking other metabolic pathways?

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Excess NADH

What is the significance of inhibited lipolysis and increased lipogenesis?

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This leads to the accumulation of fatty acids, which are deposited in the blood (increased risk of MI) and liver.

Excess production of acetyl COA which are converted into ketones leading to ketosis.

How does alcohol damage the GI tract?

General effect
Liver
Food
Nurtition 
Bowel
Increases risk of...

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▪ Causes inflammation of the tongue, stomach, pancreas, liver and intestines.
▪ Breakdown products lead to fat deposition, fibrosis and scarring of the liver.
▪ Impairs the digestion of food and absorption into blood. Alters food consumption behaviour/selection.
▪ Acetaldehyde (the oxidation product) can interfere with absorption & activation of vitamins.
▪ Motility problems …diarrhoea
▪ Increased risk of cancer…..oesophageal, liver. (hepatocellular carcinoma) and bowel (high calories).

What are the effects of alcohol on the pancreas?

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Stimulation of CCK and Secretin release from duodenum.
Changes in pancreatic blood flow and secretion.
Toxic metabolites - can lead to necrosis.
Acute pancreatitis.

Why does alcohol cause acute pancreatitis?

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Due to increased stimulation of CCK and secretin.

What are the stages of alcohol induced liver damage?

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Fatty liver > liver fibrosis > liver cirrhosis.

Steatosis

Steatosis is abnormal retention of fat (lipids) within a cell or organ.

Alcoholic steatohepatitis

Alcoholic Steatohepatitis is a chronic, progressive liver disease characterized by thickening and scarring (fibrosis) of the liver as well as possible death (necrosis) of the liver tissue, brought on by excessive, prolonged alcohol use. - induced by inflammation.

Cirrhosis

Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, is a condition in which the liver does not function properly due to long-term damage. This damage is characterized by the replacement of normal liver tissue by scar tissue.

What are the signs of cirrhosis?

``` Jaundice Spider naevi Ascites - fluid in the belly Haemetemesis Gynecomastia Confusion ```

In what way can alcohol affect the oesophagus?

Oesophageal varices

Oesophageal varices - what are they and what's the cause?

Abnormal dilatation of veins due to increase in portal vein pressure. Can cause life-threatening bleeding

How does alcohol affect neurotransmitters in the brain?

Increases dopamine Inhibits glutamate Potentiates GABA-A receptor function. Increase serotonin

In relation to alcohol what are ADH and ALDH?

``` Alcohol dehydrogenase (ADH) Aldehyde dehydrogenase (ALDH) ```

What does ALDH do?

The liver enzyme aldehyde dehydrogenase (ALDH) metabolizes acetaldehyde into acetate, a less toxic compound that breaks down into water and carbon dioxide.

What is the pathology of cirrhosis?

Growth of connective tissue destroys liver cells leading to irreversible damage.

What is the difference between alcoholic steatohepatitis and cirrhosis?

Hepatitis may be reversible (curable) whereas cirrhosis refers to permanent scarring of the liver - (often due to chronic hepatitis.

What is the pathology of alcoholic steatohepatitis?

``` Inflammation induces production and accumulation of extracellular matrix (collagen) from hepatic stellate cells. ``` This results in liver fibrosis, scar tissue forms; liver can recover but scarring remains.

What is the treatment for alcoholic steatohepatitis?

Glucocorticoids

What areas of the brain does alcohol affect?

Cerebral impairment - altered judgement, emotions and vision. Cerebellum - affecting co-ordination. Medulla - depressing cardiac and respiratory functions.

What is the long term affect of alcohol increasing dopamine temporarily?

The absence of alcohol can cause depression and anxiety.

What is the effect of alcohol blocking glutmate?

Glutamate is an major excitatory neurotransmitter which when blocked results in cognitive impairment and amnesia and an inability to learn new information.

What is the affect of alcohol potentiating GABA receptors?

GABA is major inhibitory neurotransmitter in the brain. Receptor subtypes: Alpha5 - memory impairing effects. Alpha2, alpha3 - relaxation and pleasure mediating effects. Alpha1 - sedation, anaesthesia and unsteadiness.

What subtype of serotonin does alcohol increase the release of?

5-HT

What is the effect of alcohol increasing the release of serotonin?

Alcohol increases release of serotonin (5-HT) causing one to become sleepy / even pass out. 5-HT plays a major role in the sleep-wakefulness cycle, mood and emotion.

What are some of the long term affects of alcohol on your brain?

Loss of cortical grey matter - particuarly in the prefrontal cortex. Does boost the growth of some new nerve cells, however these new cells could contribute to development of alcohol dependence and addiction.

What are the benefits of drinking alcohol in middle aged men and women?

Benefits include inhibiting atheroma formation and decreasing rate of blood coagulation.

What's the benefit of drinking red wine?

Red wine – polyphenols (such as procyanidins) reduce incidence of cardiovascular disease. Anti-atherosclerotic through suppression of excess endothelin-1 (a vasoconstrictor), inducing dilation of blood vessels.

What is considered to be 1 unit, regarding, wine, beer, cider, and shots?

Small glass of wine. Half a pint of cider / beer. 1 single shot.

Metabolism of Alcohol Flashcards

(47 cards)