topic 4 - drug addiction

Question 1

what are psycho-active drugs

Answer 1

• any chemicals that influence how we feel or act
• usually they interact with the nervous system and/or the endocrine system
• mostly act in synapses

Question 2

agonist vs antagonist at the synapse level (effect on post-synaptic cell)

Answer 2

agonist: mimics action of the neurotransmitter
antagonist: blocks action of the neurotransmitter

Question 3

agonist vs antagonist at the receptor level (effect on receptor)

Answer 3

agonist: mimics action of neurotransmitter
antagonist: blocks action of neurotransmiter

Question 4

pharmacokinetics: intake

Answer 4

• digestive tract
• respiratory tract
• through skin
• through mucous membranes
• intravenous injection (directly into blood)
• intramuscular injection
• subcutaneous injection (under the skin)

Question 5

pharmacokinetics: distribution

Answer 5

• bloodstream goes all across the body
• water-soluble molecules can be directly dissolved in the blood, but do not pass through cell membranes
• lipid-soluble molecules need carriers to transport them through the blood but can pass directly through the cell membranes

Question 6

pharmacokinetics: elimination

Answer 6

all drugs are eventually eliminated from the body:
- by chemical breakdown (by enzymes)
- by excretion (in urine)
Some drugs can be stored in the body for a long time (e.g. lipid-soluble drugs in fat tissue)
- biological half-life can vary from minutes to weeks

Question 7

mechanisms of drug tolerance

Answer 7

metabolic tolerance (better elimination of the drug)
functional tolerance:
- Change in receptor numbers and sensitivity
- Change in intra-cellular cascades

Question 8

dopamine pleasure or…?

Answer 8

-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

Question 9

Psychological dependence

Answer 9

• when drugs directly interact with the brain’s reward system
• Addict will crave the drugs, even while disliking their effects

Question 10

what is involved in the ‘reward’ system

Answer 10

The Ventral Tegmental Area

Question 11

what is involved in the ‘seeking’ system

Answer 11

Nucleus Accumbens