Synapse Questions

Explain how a presynaptic neurone is adapted for the manufacture of neurotransmitter?
Possesses many mitochondria and large amounts of endoplasmic reticulum
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Explain how the postsynaptic neurone is adapted to receive the neurotransmitter?
It has receptor molecules for neurotransmitters e.g. acetylcholine, on its membrane
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Outline the events in the transmission of information from one neurone to another across a synapse
Neurotransmitter released from vesicles in presynaptic neurone into synaptic cleft when an AP reaches the synaptic knob. Neurotransmitter diffuses across the synapse to receptor molecules on the postsynaptic neurone to which it binds, = new AP
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If a neurone is stimulated in the middle of its axon, an action potential will pass both ways along it to the synapses at each end, however the action potential will only pass one across the synapse at one end. Why?
Only one end can produce neurotransmitter and so this end alone can create an AP in the neurone on the opposite side of the synapse. Other end has no neurotransmitter.
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From your knowledge of summation, explain this difference
Low level frequency of AP isn't enough to exceed the threshold value in the postsynaptic neurone and to trigger an AP. High frequency = example of temporal summation.
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Suggest an advantage in responding to high - level stimuli but not to low ones
Reacting to low level stimuli presents little danger, high level stimuli need a response because they present more danger. Responding to all low level stimuli may overwhelm the CNS
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Explain why hyper polarisation reduces the likelihood of a new action potential being created
As the inside of the membrane is more negative than at resting potential, more sodium ions must enter in order to reach the potential difference of an action potential.
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They diffuse into the postsynaptic neurone where they generate an action potential
Sodium ions
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A neurotransmitter found in a cholinergic synapse
ATP
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It is release by mitochondria to enable the neurotransmitter to be reformed
Acetylcholine
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Their influx into the presynaptic neurone causes synaptic vesicles to release their neurotransmitter
Calcium ions
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Why is it necessary for acetylcholine to be hydrolysed by acetylcholinerase
To recycle the choline and ethanoic acid. Plus to prevent acetylcholine from continuously generating a new action potential in the postsynaptic neurone
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Other cards in this set

Card 2

Front

Explain how the postsynaptic neurone is adapted to receive the neurotransmitter?

Back

It has receptor molecules for neurotransmitters e.g. acetylcholine, on its membrane

Card 3

Front

Outline the events in the transmission of information from one neurone to another across a synapse

Back

Preview of the front of card 3

Card 4

Front

If a neurone is stimulated in the middle of its axon, an action potential will pass both ways along it to the synapses at each end, however the action potential will only pass one across the synapse at one end. Why?

Back

Preview of the front of card 4

Card 5

Front

From your knowledge of summation, explain this difference

Back

Preview of the front of card 5
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