created by Year 2 students to teach their classmates.

1. E.4 Neurotransmitters and
Synapses
Narisa and Pauline

2. Synaptic transmission
*note that neurotransmitters is received by a receptor but does not enter the
postsynaptic neuron

3. Neurotransmitters (NT)
Excitatory Inhibitory
•(+) ions to move out of
•Increase permeability of the postsynaptic cell
postsynaptic membrane
to (+) ions •Depresses postsynaptic
cell  harder to excite

4. Excitatory neurotransmitters
• Ex: Achetylcholine (Ach)
• Generates action
potential
• Increase permeability of
postsynaptic membrane
to (+) ions
• Influx of Na+
• Depolarization
• Action potential

5. Inhibitory neurotransmitters
• Ex: Gamma-aminobutryic
acid (GABA)
• Hyperpolarization
• Postsynaptic neuron more
(-)
• Cl- in or K+ out
• Difficult to generate action
potential

6. Decision-making in the CNS
• axons (many neurons) feed into the dendrite of the
postsynaptic neuron
• Each contribute to the mV of the postsynaptic neuron
• excitatory/inhibitory
• Summative effect (added up at the axon hillock)
• If summative effect of the inputs reaches threshold, an
AP is generated

7. Psychoactive drugs
Brain Personality

8. Cholinergic synapses
• Ex of NT: acetylcholine (Ach)
 Released by motor neurons
 Activates skeletal muscle
• Remaining Ach in synapse
 Fire indefinitely
• Acetylcholinesterase
 Breaks down Ach
• Parasympathetic nervous
system (E.5)
 Causes relaxation

9. Cholinergic synapses (continued)
• Cholinergic synapses are synapses that use
Ach
• Ex: Nicotine
 Stimulates transmission in cholinergic synapses
 Calming effect

10. Adrenergic synapses
• Ex of NT: noradrenaline
 Depolarizes postsynaptic
neuron
 Sympathetic system
 ‘fight or flight’
• Synapses using
noradrenaline are adrenergic
synapses
• Ex: Cocaine&amphetamines
 Alertness, energy, euphoria

11. Cholinergic Adrenergic
Neurotransmitter Acetylcholine Noradrenaline
Nervous system Parasympathetic Sympathetic
calming Increase energy and
Effect on mood alertness, euphoria
Drug(s) Nicotine Cocaine, amphet
amines

12. Drugs on synaptic transmission
*drugs have structures similar to neurotransmitters
*same chemical structure = same effect
*not broken down = stays longer = effect stronger
http://i-biology.net/options/option-e-neurobiology-and-behaviour/e4-neurotransmitters-and-synapses/

13. ADDICTION
- Tobacco products
- Stimulant
- Mimics Acetylcholine (Ach)
*Cholinergic Synapses (Body & Brain)
*Calming Effect

14. • Ach Case:
 Ach received by receptors
 Broken down by
acetylcholinesterase
• Nicotine Case:
 Nicotine received by receptors
 Nicotine molecules remains on
the receptors
*Excites postsynaptic neuron
*release a molecule called dopamine
• Dopamine: feeling of pleasure
• ‘reward pathway’ of your brain

16. Cocaine
- Adrenergic Synapse ADDICTION
- Cocoa plants
- Alertness + Euphoria
- Dopamine Release
Blocks removal of Dopamine
from the synapse  Build up
of Dopamine
Overstimulation of the
postsynaptic neuron
‘reward pathway’  Euphoria

17. http://www.thirteen.org/closetohome/animation/coca-anim-main.html

18. - Adrenergic synapses
- increased energy + alertness
*Directly into nerve cells which
carry dopamine + noradrenaline
*Moves into vesicle of presynaptic
neuron
*triggers increase in release of
neurotransmitters: more action
potentials
*Amphetamine interfere with
breakdown

19. • High concentrations of dopamine  euphoria
• High concentrations of noradrenaline  alertness
• Amphetamines  high energy

21. Excitatory Drugs
Dopamine
Neurotransmitter for CNS
Role:
way the brain controls
movement, memory, decision making
More dopamine means: causes neuron to fire
more often resulting in a euphoric feeling
Excess
Contribute to psychotic illnesses (schizophrenia)
Underproduction
Movement disorder (Parkinson’s)
http://outreach.mcb.harvard.edu/animations/synapse.swf
http://www.psych.ualberta.ca/~ITL/flash/stimulants_draft.swf

22. Inhibitory Drugs
Benzodiazepine
• Reduces anxiety
• Used against epileptic seizures
(brain disorder)
• modulate activity of GABA
(inhibitory NT)
Inhibitory NT  hyperpolarization
• Increases the binding of GABA to
receptors
Postsynaptic neuron  more
hyperpolarized

23. Effect of benzodiazepines at the synapse

24. Inhibitory Drugs
Alcohol
• Increases the binding of
GABA to the postsynaptic
membrane
Hyperpolarized
• Sedative effect
Decrease activity of glutamate
(excitatory NT)
Increase the release of
dopamine

25. Inhibitory Drugs
• Tetrahydrocannabinol (THC)
• Psychoactive chemical in marijuana
• Mimics NT anandamide
 Binds to the same receptor (cannabinoid
receptors)
• Inhibitory neurotransmitter
 Hyperpolarized
• Anandamide – role in memory functions
 Marijuana affects short-term memory
 Anandamide may be involved in
eliminating information that is not needed

26. THC and Cocaine: Mood, synapse, behavior
Marijuana
Relaxed, Mellow
Light-headed, Hazy
THC  Dilate pupils  Color Perception
Senses may be enhanced
Panic + Paranoia
SYNAPSE
*Cannabinoid receptors
Learning
Coordination
Problem solving
Short-term Memory

27. THC and Cocaine: Mood, synapse, behavior
Mechanism
*mimics anandamide
*inhibits the neurons that anandamide inhibits
*No enzyme to break down THC
*Stays in the synapse longer = greater effect
Coordination
Motor
impairment
(THC)
Short Term
Memory

28. THC and Cocaine: Mood, synapse, behavior
Cocaine
Euphoria
Talkativeness
Mental Alertness
Temporary decrease in need for food + sleep
Large amounts: erratic/violent behavior
SYNAPSE
*ability to sustain dopamine
levels in the synapse
*dopamine: ‘reward
pathway’
Longer it is there, the better
you feel

29. Causes of Addiction
• Alcohol
• Tobacco
• Psychoactive drugs
• Pharmaceuticals (some)
Body: develops a tolerance
Addiction: Chemical dependency on drugs where the drug has
‘rewired’ the brain and has become an essential biochemical in
the body
Smoking
Causes the brain to be rewired
Nicotine  mimics acetylcholine
People who smoke: crave a dopamine spike

30. Causes of Addiction
Addiction
Abused drugs: euphoria
Withdrawal:
anxiety, depression, craving
Alcohol: seizures, delirium
tremens (severe shaking)
Continued addiction: harmful
Inhaled drugs: damage lungs
Sharing needles: contract
HIV/Hepatitis B and C
Kidney disease

31. Genetic Predisposition
*Addiction + Genes
• Some people are genetically more pre-disposed to becoming addicts
• Family histories/pedigree charts  Susceptibility to addiction
• Different allele of a receptor gene, or to carry modified versions of other
genes linked to drug metabolism
• Risk-taking behavior  more likely to experiment with drugs
• Explains why some people never try drugs
• Why some people who do drugs don’t become addicts
Dopamine Receptors
Deficiency of dopamine receptors  addiction
Case: Rats
Alcohol preferring rats  20 % lower levels of
dopamine receptors
Consumed: 5g ethanol/kg EVEN when given a
choice between ethanol + water
Non-preferring rats: 1g ethanol/kg of body
weight

32. Social Factors
Determine child’s vulnerability to
substance abuse
 Family addiction
 Family parenting skills
 Mental health problems of
family/child
PEER PRESSURE!
*affects adolescents more than adults
*drugs/alcohol
*users teach new users: effects to
expect + what altered state is
desirable

33. Social Factors
British: Opium into China
SOCIAL PROBLEM
Heroin  USA
SOCIAL CATASTROPHE
Alcohol at parties:
Notion that only with alcohol can there be a party
Saudi Arabia:
Alcohol is prohibited by culture+ law
Alcoholism is rare
CHEAP and EASY ACCESS  ADDICTION

34. Dopamine Secretion
DOPAMINE:
Neurotransmitter  activate reward
pathway  pleasure/satisfaction
Cocaine use: dopamine build up
Drug Addiction
Receptors are constantly stimulated
Overstimulation  decreases the
number of receptors
Less sensitive  tolerant
Neuroadaptive change  critical for
producing addiction

35. Dopamine Secretion
Research
Knockout mice – genetically
manipulated mice addicted
to cocaine
Neurotransmitter  Glutamate
Glutamate = oversee learning
and memories which lead to
cocaine seeking

36. Which was the first country in the world, in
2003, to offer medical marijuana?
a) Germany
b) Netherlands
c) Canada
d) United States

37. Cocaine is the _______ most commonly used
illicit drug in the United States.
a) First
b) Second
c) Third
d) Fourth

38. What did the drink Coca-Cola originally
contain?

39. Scientist claim that the average
smoker will lose _____ years of
14
their life due to smoking.

40. 10
Nicotine reaches the brain in _____
seconds.