Alcohol

Question 1

Which of these is used in beverages and which of these is found in formic acid:

a. Ethyl alcohol
b. Methyl alcohol

Answer 1

Ethyl alcohol found in beverages

Methyl alcohol found in formic acid

Question 2

How is ethanol produced? (2 marks)

Answer 2

• Fermentation of sugars by yeasts.
• Fermentation causes yeast to die, distillation then increases alcohol concentration (can make spirits)

Question 3

Due to alcohol being so calorific what organ in particular can it cause a lot of muslce degeneration of? (1 mark)

Answer 3

• Brain

Question 4

What value of blood alcohol concentration is seen to cause a measurable behavioural effect?

Answer 4

0.02%

Question 5

How does ingesting food before you drink slow the absorption of alcohol? (2 marks)

Answer 5

• Pyloric sphincter delays movement to small instestine which regulates the movement of material from stomach to intestine
• This delayed movement allows dehydrogenase to break down the alcohol

Question 6

Why are women more prone to being more intoxicated than men even if they drink the same amount?

(1 mark)

Answer 6

• Men contian 60% more active alcohol dehydrogenase so they are able to break down alcohol faster

Question 7

What does alcohol dehydrogenase convert alcohol to and where does this reaction take place?

(2 marks)

Answer 7

• In liver
• Converts it inot acetaldehyde and then this is converted by aldehyde dehydrogenase (ALDH) to acetate

Question 8

What does a build in acetaldehyde dehydrogenase cause?

(1 mark)

Answer 8

• Flushing, nausea and vomitting

Question 9

Enzymes from what family convert alcohol inot acetaldehyde?

(1 mark)

Answer 9

Cytochrome P450

Question 10

How is ‘induction’ the basis for metabolic tolerance?

(2 marks)

Answer 10

• Alcohol consumed regularly - enzymes increase
  
  • Get increase in rate of metabolism of alcohol

Question 11

What the four different mehcanisms of tolerance? (8 marks)

Answer 11

1. Acute tolerance: occurs on single exposure to alcohol - feel less intoxicated on declining limb of alcohol curve
2. Metabolic tolerance: increase in P450 in liver microsomal enzymes that metabolise the alcohol. Quicker metabolism, blood levels of drug = reduced, so diminshed effects
3. Pharmodynamic tolerance: neurons adapt to continued presence of alcohola and make compensatory changes in cell function (receptors exposed to alcohol will continually adapt)
4. Behavioural tolerance: practising behaviours while under influence of alcohol allows adjustment and compensation

Question 12

What are some of the symptoms of physical dependence after prolonged use of alcohol? (3 marks)

Answer 12

• May be due to residual acetaldehyde in the body
• Gastric irritation, rebound drop in blood sufar, excess fluid loss
• some alcoholics experience delirium - can include convulsions, hallucinations, disorientation, panic attacks and unstable blood pressure

Question 13

What are some of the effects of alcohol at 0.15% and 0.35% blood alcohol concetration? (2 marks)

Answer 13

• 0.15% - start to vomit
• 0.35% - unconcious - can be seen as a mechanism of prevention to stop drinking

Question 14

What sort of brain damaged is experienced from chronic drinking?

(5 marks)

Answer 14

• Deficiency for thiamine (Vitamin B₁) - which is critical for brain glucose metabolism - causes cell death and Wernicke encepalopathy
• Wernicke Korsakoff syndrome: slective degeneration of diencephalon - causes confusion, disorientation
• Korsakoff syndrom: potenitally irreversible memory loss - anterograde amnesia
• Enlarged ventricles of the brain and extensive shrinkage of brain tissue

Question 15

What sort of treatment can help stop degeneration (but not be able to reverse it)?

(1 mark)

Answer 15

Thiamine treatment

Question 16

How can low to moderate daily dose of alcohol reduce the risk of heart disease?

(1 mark)

Answer 16

• Increases amount of good cholesterol in blood while reducing the bad

Question 17

What happens in a fatty liver after chronic use of alcohol?

(3 marks)

Answer 17

• Causes inflammation in tissue along with increased breakdown of fats into fatty acids
• Changes in adipose tissue release fatty acid into the blood
• Contributes to increased deposit of triglycerides

Question 18

What is alcohol hepatitis? (2 marks)

Answer 18

• Liver cell damage caused by accumulation of high levels of acetaldehyde
• Causes inflammation of liver, fever, jaundice and pain

Question 19

What is alcoholic cirrhosis? (1 mark)

Answer 19

• Death of liver cells stimulates scar formation and blood vesses carrying O₂ are cut off

Question 20

What is foetal alcohol syndrome? (2 marks)

Answer 20

• Pre-natal alcohol exposure - (alcohol passes through placental barrier)
• Can cause withdrawal syndrome in foetus

Question 21

What are some of the symptoms of foetal alcohol syndrome?

(4 marks)

Answer 21

1. Mental retardation
2. Low birthweight
3. Neurological problems
4. Distinctive cranial malformations

Question 22

What are some of the non-specific affect of alcohol in the neuronal membrane?

(3 marks)

Answer 22

• Alters lipid composition
• Interacts with polar heads of phospholipid
• Disturbs relationship in protein membrane

Question 23

What are some of the specific affects of alcohol in the neuronal membrane?

(3 marks)

Answer 23

• Acts at neurotransmitter binding site
• Modifies gating mechanism inside channel
• Stimulates G proteins linked to adenyl cyclase

Question 24

How does alcohol affect glutamate function?

(3 marks)

Answer 24

• Effect NMDA receptor function so affects learning and memory - as glutamate release is reduced into hippocampus
• W/drawal symptoms of less glutamate in CNS: seizures and hyperexcitability
• Excessive Ca²⁺ influx - contributes to cell death

Question 25

How does alcohol affect GABA function? | (5 marks)

Answer 25

* Binds to GABA_A receptors opens channels and allows Cl^- to enter cell and **hyperpolarise membrane** therfore increasing Cl^- and stimulating GABA release * Some of these receptors located extrasynaptically respond to more persistent action of GABA that remains in extracellular space to **produce tonic inhibition** * Repeated exposure to ethanol **reduces GABA_A mediated Cl^-** **flux**

Question 26

How does alcohol affect dopamine? | (3 marks)

Answer 26

* May increase **mesolimbic firing** indirectly secondary to its modulation of other NT in VTA e.g. those produced by GABA etc. * Reinforcement * Can have negative affect in terms of withdrawal

Question 27

How are opioids affected by alcohol? | (3 marks)

Answer 27

* Acute administration of alcohol **increase endogenous opioid production** and release *endorphins and enkephalins* * Chronic administration *reduces production* * However - has been shown in animals that an antagonist for opioid reduces alcohol consumption

Question 28

What is the difference between Type I and Type II alcoholics? (2 marks)

Answer 28

**Type I: (normally female)** * Generally begin drinking in later life and experience guilt and fear about their alcoholism **Type II: (normally male)** * Display thrill-seeking, antisocial and criminal activities; greater genetic vulnerability and start drinking at an early age

Question 29

How does detoxification by benzodiapines/ diazepines work to prevent alcohol withdrawal? (2 marks)

Answer 29

1. Makes drinking **unpleasant** as **dilsulfrin inhbits ALDH** 2. Reduce alcohol's reinforcing qualities e.g. Naltrexone and Acamprosate