topic 4 - drug addiction Flashcards
what are psycho-active drugs
- 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
agonist vs antagonist at the synapse level (effect on post-synaptic cell)
agonist: mimics action of the neurotransmitter
antagonist: blocks action of the neurotransmitter
agonist vs antagonist at the receptor level (effect on receptor)
agonist: mimics action of neurotransmitter
antagonist: blocks action of neurotransmiter
pharmacokinetics: intake
- digestive tract
- respiratory tract
- through skin
- through mucous membranes
- intravenous injection (directly into blood)
- intramuscular injection
- subcutaneous injection (under the skin)
pharmacokinetics: distribution
- 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
pharmacokinetics: elimination
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
mechanisms of drug tolerance
metabolic tolerance (better elimination of the drug)
functional tolerance:
- Change in receptor numbers and sensitivity
- Change in intra-cellular cascades
dopamine pleasure or…?
-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
Psychological dependence
- when drugs directly interact with the brain’s reward system
- Addict will crave the drugs, even while disliking their effects
what is involved in the ‘reward’ system
The Ventral Tegmental Area
what is involved in the ‘seeking’ system
Nucleus Accumbens
