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Synapse Transmission, labelling-a-synapse1 - Coggle Diagram
Synapse Transmission
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Common neurotransmitters
Acetycholine
- Excitatory neurotransmitters involved in movement, memory, learning and sleeping.
- Too much = depression
- Too little = dementia.
Serotonin
- Involved in emotion, mood, sleeping and eating.
- Too little = depression.
GABA
- Inhibitory neurotransmitter
- Too little = anxiety disorders.
Dopamine
- Helps with movement, attention and learning.
- Too much = schizophrenia.
- Too little = depression and Parkinson's disease.
Noradrenaline
- Closely related to adrenaline.
Synaptic transmission
- A synapse is that junction between two neurons.
The synaptic cleft is the gap between the cells at a synapse.
- The presynaptic neuron has a synaptic knob. It contains synaptic vesicles filled with neurotransmitters.
- When an electrical impulse reaches the end of neuron it causes neurotransmitters to be released into the synaptic cleft. They diffuse across to the postsynaptic membrane and bind to specific receptors that recognise it and are activated by that particular neurotransmitter.
- Once the receptor has been activated, it produces either excitatory or inhibitory effects on the synaptic neuron.
Key features
Unidirectional
Because the receptors are only on the postsynaptic membrane, impulses can only travel one direction.
Re-uptake
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Taken back to the presynaptic neuron - how long this process takes determines how prolonged the effects are.
eg.
Some antidepressants prolong the action of neurotransmitters by inhibiting the re-uptake process, leaving the it in the synapse for longer.
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What, Why, blah blah.
- Once a action potential has arrived at the terminal button it must be transferred to another neuron.
- When a neuron ends there is a small gap that the action potential must cross.
- aka. cross between the presynaptic neuron to the membrane of the postsynaptic neuron.
- At the end of the axon are a number of sacs known as synaptic vesicles.
- They contain chemical messages that assist in the transfer of impulse - neurotransmitters.
- As the action potential reaches the synaptic vesicles, it causes them to release their contents - exocytosis.
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