Drug Addiction

Question 1

Drugs definition

Answer 1

Chemical substances which interact with the biochemistry of the body in one of these ways:

1. Inhibit or reinforce enzyme activity
2. Block or reactivate receptors
3. Interact with neurotransmitters or hormones in other ways
4. Attack ‘invaders’ (eg antibiotics)

Question 2

What are psychoactive drugs?

Answer 2

Any chemicals that influence the way we feel or act.
Usually they interact with the nervous system and/or the endocrine system
Mostly, they act at synapses (among other places)

Question 3

Agonist

Answer 3

Mimics the action of the neurotransmitter on both the post-synaptic cell and receptor

Question 4

Antagonist

Answer 4

Blocks the action of the neurotransmitter on both the post-synaptic cell and receptor

Question 5

Intake of pharmacokinetics (fastest to slowest)

Answer 5

Digestive tract
Respiratory tract
Through skin
Through mucous membranes
Intravenous injection (directly into the blood)
Intramuscular injection (into the muscles)
Subcutaneous injection (under the skin)

Intravenous
Smoked
Intranasal
Oral

Question 6

Water soluble drugs

Answer 6

Molecules can be directly dissolved in the blood, but do not pass through cell membranes

Question 7

Lipid soluble drugs

Answer 7

Molecules need carriers to transport them through the blood, but can pass directly through cell membranes

Question 8

Blood-brain barrier

Answer 8

Usually capillaries have little gaps in organs to let blood through, however not in the brain. If the drug is lipid soluble however it can just diffuse through the capillary wall.

Question 9

How are drugs eliminated from the body?

Answer 9

Chemical breakdown (enzymes) or excretion (urine). Some drugs can be stored for a long time, especially lipid soluble drugs in fat tissue.
Biological half-life can vary from minutes to weeks.

Question 10

Drug Tolerance

Answer 10

You need a higher dose to get the same effect and the same dose will have less of an effect

Question 11

Why do we get drug tolerance?

Answer 11

The body maintains homeostasis.

Mechanisms are either metabolic tolerance (better elimination of the drug) or functional tolerance (change in receptor numbers, change in receptor sensitivity, change in intra-cellular cascades)

This means the body produces opposite effects on the drug when the drug is away - withdrawal symptoms

Question 12

Psychological Drug Dependence

Answer 12

Uses operant conditioning. Certain parts of the brain cause a behaviour to become more likely if neurons fire in it.

Question 13

Mesotelencephalic Dopamine System

Answer 13

Believed to cause psychological dependence (especially the link between VTA and nucleus accumbens). Dopamine is highly involved in reward

Question 14

How do you test whether dopamine release causes the rewarding effect in the brain?

Answer 14

Block the action of dopamine while stimulating (like Stellar, Kelley and Corbett, 1983)

Question 15

Is dopamine for pleasure?

Answer 15

Dopamine is released with punishing stimuli as well
Overtrained rats do not release dopamine upon reward
Dopamine blockers make rats work less hard for food, but they still enjoy it.
Hypothesised it’s responsible for seeking.

Question 16

Cocaine and Dopamine

Answer 16

Cocaine increases dopamine levels, directly activating the reinforcement system.

Question 17

Cocaine and mono-anergic synapse

Answer 17

Blocks the reuptake channel either by changing shape of the neurotransmitter or the channel

Question 18

Amphetamines and mono-anergic synapse

Answer 18

Pushed the neurotransmitter out of the synapse.