the effect of recreational drugs on the transmission process

what are drugs?

chemicals that have an effect on humans

what is meant by recreational drugs?

drugs taken for pleasure

why are recreational drugs considered psychoactive?

they have an effect on the central nervous system

what is meant by drugs which have a specific mode of action at the synapse?

they act in a specific way

what is an example of a drug with no specific mode of action?

alcohol, which has many effects

what is the reward pathway or pleasure centre in the brain?

where pleasure seems to be so desired that someone will continue to behave in such a manner that the pleasure is received, the desire for pleasure over-rides other drives

what is included in the mesolimbic reward pathway?

the ventral tegmental area in the midbrain, a large population of dopamine neurones

what does nicotine directly affect?

the dopamine receptors in the area of the brain that is the reward pathway

which natural neurotransmitter does nicotine mimic the actions of?

acetylcholine

what receptor does nicotine bind to?

a certain type of acetylcholine receptor, called nicotinic receptors

what do nicotine receptors cause?

an impulse in the neurone which gives an action potential down the axon of that neurone, releasing more neurotransmitter (dopamine), giving the pleasurable effects of taking nicotine

what does the binding of nicotine overtime result in?

a decrease in dopamine receptors and a change in the shape of the cell, meaning more nicotine is needed to stimulate the postsynaptic neurone to a normal level, due to it having less receptors

what is desensitisation?

when more of a substance is required to achieve the same response

how can desensitisation lead to addiction?

more of the substance is needed just to maintain what was normal functioning

what does cocaine work on?

the reward pathway and dopamine receptors

what idea does cocaine draw on?

that there is reuptake by the presynaptic neurone of neurotransmitter left in the synaptic gap

what does cocaine block the binding site on?

the reuptake receptor, stopping the reuptake of dopamine back into the presynaptic neurone, this leads to excess dopamine in the synapse and over-stimulation at the postsynaptic receptors

what damage can be caused by over-stimulating the dopamine receptors of the postsynaptic neurone?

consequences of desensitisation and addiction, as postsynaptic neurones become damaged and fewer

what does cannabis bind to?

cannabinoid receptors

where can cannabinoid receptors be found?

in many regions of the brain, with many cannabinoid receptors in the hippocampus

what happens when cannabis binds to cannabinoid receptors?

they are blocked, meaning there is less activity in neurones in the hippocampus, so memories can be affected

what happens in the reward system when taking cannabis?

more dopamine is released, giving the "high"