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9 Cards in this Set
- Front
- Back
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What are the Events in synaptic transmission? |
•Presynaptic action potential •Depolarisation of synaptic terminal •Opening of voltage-gated Ca channels •Ca entry and fusion of vesicles with membrane•Transmitter release (and re-uptake / degradation) •ACh receptor-activated cation channels open•Activation of Na and K channels |
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What if the post synaptic responseis sub threshold? |
Sub threshold signal – no action potential Supra threshold stimulus fires an action potential |
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Why might there be Reduced vesicle release? |
Low calcium High magnesium Curare (poison) |
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Why might there be Sub threshold miniature endplatepotentials MEPPs? |
Low calcium High magnesium Curare (poison) |
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When do MEPPs occur? |
MEPPs vary in sizeand occur at random Random release of vesiclesgenerates MEPPs |
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What are Excitatory and Inhibitory Postsynaptic Potentials? |
EPSPs and IPSPs are sub threshold events whichdetermine whether a neuron will reach threshold to fire anaction potential – or not. PSPs are called excitatory (or EPSPs) if they increase the likelihood of a postsynaptic action potential occurring, and inhibitory (or IPSPs) if they decrease this likelihood |
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What drives a neurone to threshold? |
Sufficient EPSPs will drive a neuron to threshold |
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How do EPSPs and IPSPs interact? |
EPSPs and IPSPs interact in time andspaceTemporal summation Spatial summation |
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What is summation? |
Summation, which includes both spatial and temporal summation, is the process that determines whether or not an action potential will be triggered by the combined effects of excitatory and inhibitory signals, both from multiple simultaneous inputs (spatial summation), and from repeated inputs (temporal summation |
