Junctions between the axon of one neurone & the dendrite of an adjacent neurone
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What are neuromuscular junctions?
Synapses between neurones & muscles
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What do neurotransmitters do?
Chemicals which transmit impulses from one neurone to another and diffuse across a very small gap
(synaptic cleft)
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What does the pre-synaptic neurone do?
Releases the neurotransmitter
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What does the post-synaptic neurone do?
Receives the diffusing neurotransmitter
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What are 3 adaptations of the neurone for synapse?
-Thickened end of pre-synaptic membrane
-Large numbers of mitochondria
-Contains receptors(post-synaptic membrane
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What is the principle of synapses?
Neurotransmitters that pass across the synaptic cleft will cause depolarisation in the post-synaptic neurone allowing the nerve impulse. to continue from one neurone to the next
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What are 3 advantages of synapses?
-Prevent overstimulation of effectors(muscles)
-Ensure unidirectionality
-Allow nervous communication within body
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What is spatial summation?
Simultaneous stimulation of several synaptic knobs may cause depolarisation of the PSM,even though each synaptic knob may release insufficient neurotransmitter substance on its own
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What is temporal summation?
Repeated stimulation of the same synaptic knob may occur, until neurotransmitter substance has been released to cause depolarisation
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Why have inhibitory synapses?
Help by reducing the input of background stimuli that would clutter up the nervous activity in the brain/may prevent some reflex actions
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What does an impulse occurring in the post synaptic membrane depend on?
The contribution of excitatory & inhibitory synapses
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