A synapse transmits nerve impulses between neurons. During transmission: 1) an electrical impulse travels along an axon, 2) neurotransmitters are released, and 3) these chemicals bind to receptors on the next neuron, stimulating it. Neurotransmitters like serotonin and dopamine relay signals between neurons and control functions like mood, sleep, and movement. Drugs like ecstasy and cocaine affect synapses by preventing neurotransmitter reabsorption, increasing their levels in the synapse. Nobel Prizes have been awarded for discoveries relating to neurotransmitters, synaptic transmission, and their roles in conditions like Parkinson's and memory formation.

1. B6 – BRAIN AND MIND
SYNAPSES
GCSE SCIENCE AND ADDITIONAL
SCIENCE
Sig’s School Work Help

2. WHAT IS A SYNAPSE?
A tiny gap between neurones that transmits nerve impulses
from one neurone to the next

3. STAGES: DIAGRAM:
1) An electrical impulse travels along an
axon.
2) This triggers the nerve-ending of a
neuron to release chemical messengers
called neurotransmitters.
3) These chemicals diffuse across the
synapse (the gap) and bind with
receptor molecules on the membrane of
the next neuron.
4) The receptor molecules on the second
neuron bind only to the specific
chemicals released from the first
neuron. This stimulates the second
neuron to transmit the electrical
impulse.

4. NEUROTRANSMITTERS
What Are They?
• Neurotransmitters are the brain chemicals that communicate information
throughout our brain and body
• They relay signals between nerve cells, called “neurons.” The brain uses
neurotransmitters to tell your heart to beat, your lungs to breathe, and
your stomach to digest.

5. TYPES OF NEUROTRANSMITTERS
• Acetylcholine
• Motor control, learning, memory, sleep, dreams
• Serotonin
• Emotion, impulses, dreams
• Norepinephrine
• Alertness, vigilance, fear reaction
• Epinephrine
• Energy boost
• Dopamine
• Rewards, motivations, motor control
• Frequently associated with addictions
• Melatonin
• Sleep cycle regulation
• Endorphins
• Rewards, pain reduction
• Glutamate
• Regulates learning and memory

6. HOW DO DRUGS AFFECT SYNAPSES?
• Some drugs stop the impulse from passing across the synapse. Drugs
such as curare (the South American plant toxin used in arrow poison)
do this. They cause complete paralysis, and even stop the person from
breathing
• Other drugs stimulate the synapse so that once an impulse crosses the
gap the impulse is repeated over and over again. Drugs such as
strychnine do this. They cause all the muscles in the body to go into a
continuous spasm of constriction. This also stops the person from
breathing.

7. HOW DO DRUGS AFFECT SYNAPSES?
Serotonin
• A transmitter substance found at the synapses in the brain
• An increase in serotonin levels in the synapses makes us feel happier.
• Serotonin is normally absorbed by receptor molecules on the other side of the synapse. This prevents the levels
of serotonin from increasing.
Ecstasy
• An illegal drug that affects the working of the chemical transmitter substance in nerve synapses in a similar way
to antidepressants
• Ecstasy (also called MDMA) is a drug that blocks the serotonin receptor sites in the synapses in the brain. This
prevents the serotonin from being absorbed by the receptor molecules. As a result, the level of serotonin in the
synapse increases. This produces a feeling of wellbeing.

8. HOW DO DRUGS AFFECT SYNAPSES?
Dopamine
• In the normal communication
process, dopamine is released by a
neuron into the synapse, where it
can bind to dopamine receptors on
neighboring neurons.
• Normally, dopamine is then recycled
back into the transmitting neuron by
a specialized protein called the
dopamine transporter.
Cocaine
• If cocaine is present, it attaches to
the dopamine transporter and blocks
the normal recycling process,
resulting in a buildup of dopamine in
the synapse, which contributes to the
pleasurable effects of cocaine.

9. SCIENTISTS WHO RECEIVED A NOBEL PEACE PRIZE FOR
THEIR WORK ON NERVES
Arvid Carlsson, Paul Greengard and Eric Kandel
• Nobel Prize Winners in Physiology or Medicine for 2000
• For their discoveries concerning "signal transduction in the nervous system”
Arvid Carlsson:
• His research has led to the realization that Parkinson's disease is caused by a lack of dopamine in certain parts of the
brain and that an efficient remedy (L-dopa) for this disease could be developed.
Paul Greengard:
• Rewarded for discovery of how dopamine and a number of other transmitters exert their action in the nervous system. The
transmitter first acts on a receptor on the cell surface. This will trigger a cascade of reactions that will affect certain "key
proteins" that in turn regulate a variety of functions in the nerve cell
Eric Kandel:
• Rewarded for discoveries of how the efficiency of synapses can be modified, and which molecular mechanisms that take part.
With the nervous system of a sea slug as experimental model he has demonstrated how changes of synaptic function are
central for learning and memory.