What are synapses?
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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What is one important role of synapses?
-Filtering low level background stimuli
-Preventing overload/overstimulation
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What is the primary transmitter in the CNS of vertebrates?
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What is the neurotransmitter involved in involuntary responses such as the regulation of gut movements?
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What is GABA?
A neurotransmitter released at an inhibitory synapse
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What does GABA cause?
The flow of negative ions into the post synaptic membrane-causing hyper polarisation
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What is one role of GABA?
Help reduce anxiety/panic attacks
(dampening down of the nerve pathways in the brain)
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What does agonistic mean?
term used to describe the action of chemicals, which mimic transmitter substances at synapses
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What happens if fresh water is contaminated?
Algae produce a poison called anatoxin
(agonistic chemical)
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What is a symptom of anatoxin poisoning?
Animal produces large amounts of saliva
(due to the continuous stream of nerve impulses)
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What do antagonistic chemical block?
The action of transmitter substances at synapses
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What is the name of the South American poison which blocks the action of acetylcholine at the junction between the nerve and muscle?
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What does curare poisoning lead to?
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What are Beta-blockers?
Drugs which are important in the treatment of heart disease
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Card 2


What are neuromuscular junctions?


Synapses between neurones & muscles

Card 3


What do neurotransmitters do?


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Card 4


What does the pre-synaptic neurone do?


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Card 5


What does the post-synaptic neurone do?


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