recreational drugs

Question 1

what are drugs?

Answer 1

• chemicals that have an effect on humans

Question 2

what are recreational drugs?

Answer 2

• cocaine
• heroin
• cannabis
• ecstasy
• etc

Question 3

why are they called ‘recreational’?

Answer 3

• because they are taken for pleasure
• they have an effect on the central nervous system they are called ’psychoactive’

Question 4

what is the mode of action of drugs at the synapse?

Answer 4

• some drugs do not have a specific mode of action e.g. alcohol has many effects
• however, drugs do have a specific mode of action at the synapse which means they act in a specific way

Question 5

what is the reward pathway/pleasure centre?

Answer 5

• in the septum area of the brain
• where the pleasure seems to be so desired that someone or an animal continue to behave in such a manner that the pleasure is received, even when starving or thirsty
• desire for the pleasure over rides other drives

Question 6

what is one reward pathway?

Answer 6

• mesolimbic pathway - includes ventral tegmental area in midbrain (large population of dopamine)

Question 7

what are the effects of nicotine on the transmission process in the cns?

Answer 7

• nicotine works on reward pathway to give pleasure - leads to addiction because organism will act in order to stimulate reward pathway
• directly affects dopamine receptors in area of brain that is the reward pathway
• nicotine mimics the actions of acetylcholine, natural neurotransmitter
• nicotine binds to a certain type of acetylcholine receptor, called nicotinic receptors
• when either acetylcholine or nicotine bind to these receptors, same thing happens
• nicotine receptors down the axon of that neuron, releasing more neurotransmitter - dopamine
• dopamine gives feelings of pleasure, hence pleasurable effects of taking nicotine

Question 8

side effects of nicotine effect in cns

Answer 8

• binding over time affects receptors, and causes decrease in dopamine receptors
• also a change in shape of cell
• when nicotine is not there, because there are not so many receptors on postsynaptic neuron, more dopamine will be required to stimulate postsynaptic neuron to ’normal’ level
• this is called desensitisation, when more of a substance is needed to achieve same response
• leads to addiction because nicotine is needed just to maintain what was normal functioning

Question 9

what is the effect of cocaine on the transmission process of the cns?

Answer 9

• also works with the reward pathway and dopamine receptors, but does it in different way
• draws on idea that there is reuptake by pre synaptic neuron of neurotransmitter left in synaptic gap
• blocks binding site on reuptake receptor and stops reuptake of dopamine back into pre synaptic neuron
• blocking of reuptake means excess dopamine in synapse which leads to over-stimulation at postsynaptic receptors
• this time there is not a ‘foreign’ substance to bind to dopamine receptors but there is more dopamine than usual
• same feeling is achieved as with nicotine. as with nicotine, effect of over-stimulating dopamine receptors of postsynaptic neuron is that they come damaged and they become fewer, with same consequence of desensitisation and addiction
• cocaine acts on the receptors in reward pathway within seconds

Question 10

what is the effect of cannabis on the transmission process in the cns?

Answer 10

• acts by binding on to cannabinoid receptors
• one type of cannabinoid receptors (CB1) is found in many regions of the brain
• there are many cannabinoid receptors in the hippocampus and taking cannabis can affect memory function
• binds to the cannabinoid receptors, effectively blocking them which means there is less activity in neurons in hippocampus so making memories can be affected by taking cannabis

Question 11

side effects on cannabis on cns

Answer 11

• in reward system more dopamine is released and it is this excess dopamine in reward system that gives them ’high’
• affect in memory