Download mode-of-action-of-recreational

KA 3: The cells of the nervous system
and neurotransmitters at synapses
(a) Structure
and function
of neurones
NS cells and
neurotransmitters
at synapses
(b)
Neurotransmitters
at synapses
(e) Mode of action
of recreational
drugs
(d)
Neurotransmitters,
mood and behaviour
(c) Function of converging,
diverging and reverberating
pathways
By the end of this section you will
be able to …..
• State 4 ways in which recreational drugs
can work in the body
• State 4 features that are altered if a
person’s neurochemistry is changed
• State the link between recreational drugs
and the reward circuit
• State what is meant by sensitisation and
what it can lead to
• State what is meant by desensitisation and
what it can lead to
Recreational Drugs
• The use of recreational drugs can affect
the transmission of nerve impulses in the
reward circuit of the brain.
• This alteration in a persons
neurochemistry can lead to changes in;
– Mood (person feels happier/more
confident/aggressive)
– Cognition (becomes poorer at carrying out
complex mental tasks)
– Perception (misinterprets environmental
stimuli)
– Behaviour (stay awake for longer/talk to
themselves)
Mode of action of recreational drugs
• Recreational drugs may:
– Stimulate the release of neurotransmitters
– Imitate the action of neurotransmitters
(agonists)
– Block the binding of neurotransmitters
(antagonist)
– Inhibit the re-uptake or enzymatic
degradation of neurotransmitters
• https://www.youtube.com/watch?v=ukFj
H9odsXw (12.00, up to 8.05)
Case studies
Cocaine
• Cocaine blocks dopamine
re-uptake channels and
produces a feeling of
wellbeing and untapped
reserves of energy.
• Can induce hallucinations,
aggressive and violent
behaviour.
Cannabis
• Cannabis acts first as a
pleasure stimulant and
then as a sedative.
• Contains cannabionoids
which bind to receptors
and mimic the effect of a
natural neurotransmitter
which is why its medical
use is approved in many
countries.
• Heavy use can lead to lung
disease and schizophrenia
Case studies
MDMA (Ecstasy)
• MDMA inhibits the reuptake of serotonin
promoting a temporary
heightened sense of
wellbeing.
• Can result in
overheating,
dehydration, anxiety,
panic attacks, paranoia
and depression.
Nicotine
• Nicotine has a soothing
effect and helps
smokers concentration.
• Nicotine binds to
nicotinic acetylcholine
receptors which
increases the level of
dopamine in the reward
circuit of the brain
resulting in euphoria.
Drug Addiction
• Drug addiction
can be defined
as a chronic
disease that
causes the
sufferer to seek
out and use the
drug, regardless
of consequences.
Drug Sensitisation
• This is the increase in the number and
sensitivity of neurotransmitter
receptors as a result of exposure to
drugs that are antagonists e.g. nicotine.
• This leads to addiction.
Drug Desensitisation
• This is a decrease in the number and
sensitivity of neurotransmitter
receptors as a result of exposure to
drugs that are agonists e.g. cannabis.
• This leads to drug tolerance.
Drug Tolerance
• A drug user is said to have built up a
drug tolerance when their reaction to a
drug has decreased and larger doses of
the same drug is required to produce
the same effect.
By the end of this section you will
be able to …..
• State 4 ways in which recreational drugs
can work in the body
• State 4 features that are altered if a
person’s neurochemistry is changed
• State the link between recreational drugs
and the reward circuit
• State what is meant by sensitisation and
what it can lead to
• State what is meant by desensitisation and
what it can lead to
Tasks…
• Complete Q 2 from pg 276 of the
textbook.
• Complete pg 277; what you should know.