Drug addiction Flashcards
(39 cards)
define drugs
Chemical substances which interact with biochemistry of the body
roles of drugs
Inhibit or reinforce enzyme activity Interact with neurotransmitters/hormones
Block or activate receptors
Attack “invaders”
define psychoactive drugs
Any chemicals that influence the way we feel or act
Usually interact with the nervous system or endocrine system
Act at synapses
define agonist
mimics neurotransmitter action
define antagonist
blocks action of a neurotransmitter
routes of drug intake
- Digestive tract
- Respiratory tract
- Skin
- Mucous membranes
- Intravenous injection (directly into blood)
- Intramuscular injection (direct to muscles)
Subcutaneous injection (under skin)
what do water soluble drugs refer to
directly dissolved in blood but do not pass through cell membranes
what do lipid soluble drugs refer to
need carriers to transport around the blood - but can pass directly through cell membranes
what are the differences between capillaries in the brain and in the body
in the blood they contain epithelial cells, so water soluble drugs can pass through
in the brain capillaries do not contain epithelial cells
what do endothelial cells have that allows fat soluble drugs to pass through
lipid bilayer
what is a key characteristic of psychoactive drugs
lipid soluble in order to have an effect on the brain and behaviour
What are the two methods of elimination of drugs from the body
By chemical breakdown (by enzymes)
By excretion (in urine)
what is a biological half life
How long it takes to go from peak concentration in the blood stream to half concentration
what is metabolic tolerance
The body becomes more efficient at breaking down or eliminating the drug, often due to increased activity of liver enzymes
what is functional tolerance
The body (especially the brain) becomes less responsive to the drug at its site of action on receptors
what is sensitisation
Repeated exposure to a drug leads to an increased effect over time
why do withdrawal effects occur
drug exposure leads to neural changes to counteract the effects
neural adaptations without the presence of the drug have opposite effects
what does the classical conditioning model suggest about drug addiction
Drug initially a NS, with primary effects as US and compensatory reactions as UR
after long term exposure, drug becomes a CS producing CR of compensatory reactions
evidence for tolerance as context dependent
overdosing easier in novel settings
withdrawal symptoms occur in familiar settings
what does operant conditioning suggest about drug addiction
positive reinforcement= taking drug to produce pleasurable effects
negative reinforcement= taking drug to remove unpleasant effect
what is Intra-cranial Self-stimulation
Self-administration of electrical stimulation of brain’s reward pathway, resulting in dopamine release
what may psychological dependence refer to
When drugs directly interact with the brain’s reward system
Addict will crave the drugs, even while disliking their effects
brain stem in drug addiction
Brain area associated with survival functions – reward processing, autonomic functions and withdrawal
areas within the brain stem
medulla
pons
midbrain
