drugs & neurotransmitters

Question 1

what are neurotransmitters?

Answer 1

• chemical messengers that act between the neurones in the brain

Question 2

excitatory neurotransmitters

Answer 2

• increases positive charge of the post synaptic neurone making the AP more likely to fire

Question 3

inhibitory neurotransmitters

Answer 3

• increases negative charge of the post synaptic neurone making the AP less likely to fire

Question 4

GABA

Answer 4

• inhibitory, calming function
• blocks nerves from firing which brings the feeling of calm and tranquility
• low GABA levels linked to epilepsy, restlessness and anxiety

Question 5

dopamine

Answer 5

• excitatory and inhibitory
• associated with pleasure feelings
• linked to drug addiction

Question 6

serotonin

Answer 6

• excitatory
• gives happiness and good mood, regulates the sleep - wake cycle
• low levels linked to depression and anxiety

Question 7

agonists

Answer 7

• nicotine, cannabis, heroin
• imitate natural neurotransmitters, ‘fooling’ the brain into activating pleasure centres - more powerful than natural neurotransmitters

Question 8

antagonists

Answer 8

• amphetamines
• massively boost the normal number of neurotransmitters, triggering the brain’s pleasure centres

Question 9

cocaine

Answer 9

• stimulant effect on CNS, especially brain’s main reward system
• greatest impact on activity of dopamine
• cocaine blocks re-uptake of dopamine by binding to dopamine transporter molecules on the terminal buttons of the presynaptic neurone
• as cocaine prevents this process, the synapse is flooded with surplus quantities of dopamine, all available fro binding with the post synaptic neurone

Question 10

long term effects of cocaine

Answer 10

• after repeated use, dopamine receptors become down regulated - quantity of dopamine declines

Question 11

heroin

Answer 11

• depressant effects on CNS, slowing down activity
• usually injected intravenously and most of it is processed in the brain into the closely related opioid, morphine
• Morphine binds with a specific opioid receptor at the synapse, found in the cerebral cortex, limbic system and hypothalamus
• Heroin / morphine receptors exist because the CNS has its own opioid system
  – endorphins and enkephalins are produced by the body as natural painkillers. Heroin taps into this natural opioid system, binding with receptors of the system to massively enhance the natural response

Question 12

long term effects of heroin

Answer 12

• repeated use results in down regulation
• opioid receptors on post synaptic neurones constantly bind to morphine molecules, desensitising them to effect of the drug