1. NS cells and neurotransmitters at synapses
KA 3: The cells of the nervous system and neurotransmitters at synapses
(a) Structure and function of neurones
(e) Mode of action of recreational drugs
NS cells and neurotransmitters at synapses
(d) Neurotransmitters, mood and behaviour
(b) Neurotransmitters at synapses
(c) Function of converging, diverging and reverberating pathways

2. 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
Can mimic neurotransmitters. Changes in neurochemistry alter mood, cognition, perception and behaviour.
Many recreational drugs affect neurotransmission in the reward circuit of the brain.
Drug addiction/tolerance.
Sensitisation is an increase in the number and sensitivity of neurotransmitter receptors as a result of exposure to drugs that are antagonists and leads to addiction. Desensitisation is a decrease in the number and sensitivity of receptors as a result of exposure to drugs that are agonists and leads to drug tolerance.
Recreational drugs may stimulate the release of neurotransmitters, imitate their action (agonists), block their binding (antagonists), and/or inhibit their re-uptake/enzymatic degradation.

3. 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)
Explanation from 269

4. 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
Recreational drugs may stimulate the release of neurotransmitters, imitate their action (agonists), block their binding (antagonists), and/or inhibit their re-uptake/enzymatic degradation.

5. https://www.youtube.com/watch?v=ukFjH9odsXw (12.00, up to 8.05)

6. Case studies Cocaine Cannabis
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 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

7. Case studies MDMA (Ecstasy) Nicotine
MDMA inhibits the re-uptake of serotonin promoting a temporary heightened sense of wellbeing.
Can result in overheating, dehydration, anxiety, panic attacks, paranoia and depression.
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.

8. 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.

9. 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.
18.3 crop out relevant part

10. 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.
picture

11. 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.

12. 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
Can mimic neurotransmitters. Changes in neurochemistry alter mood, cognition, perception and behaviour.
Many recreational drugs affect neurotransmission in the reward circuit of the brain.
Drug addiction/tolerance.
Sensitisation is an increase in the number and sensitivity of neurotransmitter receptors as a result of exposure to drugs that are antagonists and leads to addiction. Desensitisation is a decrease in the number and sensitivity of receptors as a result of exposure to drugs that are agonists and leads to drug tolerance.
Recreational drugs may stimulate the release of neurotransmitters, imitate their action (agonists), block their binding (antagonists), and/or inhibit their re-uptake/enzymatic degradation.

13. Tasks… Complete Q 2 from pg 276 of the textbook.
Complete pg 277; what you should know.