5.6 Flashcards
many drugs work by
interacting with synapses
Nicotine is similar in shape to acetylcholine which means that it
binds to acetylcholine receptors in the postsynaptic membrane
Nicotine stimulates the synapses in the ganglia of the sympathetic nervous system -
causes the HR and BR to increase and BP rises
Brain - synapses that use acetylcholine are stimulated - user’s reaction time becomes faster and they feel more energised
Cocaine affects synapses that use dopamine as a
neurotransmitter
(Cocaine) after dopamine has been released into the synaptic cleft it is transported back into the
presynaptic cleft so that it can be used again
(Cocaine) the dopamine is taken back into the presynaptic neurone via
specific dopamine transporters
Cocaine fits into these dopamine transporters and prevents
dopamine from binding to them - dopamine remains in the synaptic cleft, causing repeated stimulation of the postsynaptic neurone
(Cocaine) user experiences pleasant feelings that
encourage them to take the drug again
LSD is a
synthetic drug
LSD causes
powerful hallucinations
LSD acts mainly on synapses that use another kind of monoamine transmitter -
serotonin
LSD is similar in shape to
serotonin
(LSD) 2 different kinds of serotonin receptors on postsynaptic membranes:
Type 1
Type 2
When LSD fits into type 1 serotonin receptors, it opens sodium channels in the postsynaptic neurone and stimulates the
postsynaptic neurone
When LSD fits into type 2 serotonin receptors on postsynaptic membranes it blocks the receptors and prevents serotonin from binding - therefore causes
inhibition of the postsynaptic neurone
Inhibitory neurotransmitters are normally present in dopamine synapses, inhibiting the release of
dopamine
The body naturally produces a cannabinoid substance called
anandamide
Anandamide binds to cannabinoid, or THC receptors on the neurones that produce this inhibitor. This stops these neruones releasing the inhibitor and allows dopamine to be released by the
dopamine releasing neurones
marijuana contains a chemical called THC which is
very similar in shape to anandamide
THC binds to the cannabinoid or THC receptors and suppresses the release of the inhibitory neurotransmitter as a result
dopamine is released
Anadamide breaks down very quickly in the body so it causes only a temporary release of
dopamine
THC however, remains for much longer, causing a
greater release of dopamine and a lasting ‘high’
