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21 Cards in this Set
- Front
- Back
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Where do graded potentials occur? |
On the cell membrane of the nerve |
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What happens if graded potentials are big enough or there are enough of them occurring simultaneously? |
The membrane is depolarized to threshold |
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What happens if graded potentials arebig enough, or if enough occur simultaneously, and the membrane is depolarized tothreshold? |
Sets off an action potential, which spreads down the nerve axon |
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Define a synapse |
Junction between two neurons |
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What happens to the presynaptic neuron when an action potential runs through it? |
It depolarizes |
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What happens after an actionpotential depolarizes the presynaptic membrane? |
Voltage-gated Ca++ channels open, Ca++ enterspre-synaptic axon terminal |
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What happens after voltage-gated Ca++ channels open, Ca++ enterspre-synaptic axon terminal? |
Ca++ triggers exocytosis of neurotransmitter. |
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What happens after Ca++ triggers exocytosis of neurotransmitter? |
Neurotransmitterbinds to receptor on post-synaptic cell membrane. |
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What happens after neurotransmitterbinds to receptor on post-synaptic cell membrane? |
Post-synapticneuron responds. |
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Name three reasons why a signal will stop |
The neurotransmitter will be: Degraded by enzymes Taken back up by presynaptic neuron Diffuse away from the synapse |
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What does EPSP stand for? |
Excitatory Post-Synaptic Potential |
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What does IPSP stand for? |
Inhibitory Post-Synaptic Potential |
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Neurotransmitters can cause _______ or ______ of the post-synaptic neuron |
depolarization or hyperpolarization |
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What happens when cation channels of a depolarized synaptic neuron open? |
More sodiummoves in than potassium moves out due to stronger electrochemical force, thus creating an EPSP |
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What happens when cation channels of a hyperpolarized synaptic neuron open? |
Potassium channels open, thus creating an IPSP |
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What is temporal summation? |
Adding together of EPSP's or IPSP's generated by firing of the same presynaptic terminal at high frequency |
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What is spatial summation? |
Adding together of EPSP's or IPSP's generated by firing of two or more presynaptic neurons simultaneously |
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Give an example of IPSP's and EPSP's |
During withdrawal reflex: EPSP's exciting motor neuron to biceps IPSP's inhibiting motor neuron to triceps |
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What is grand postsynaptic potential (GPSP) |
Compositepotential on the post-synaptic membrane due to all EPSP’s and IPSP’s occurringat the same time. |
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When and wherere are action potentials generated? |
In the initial segment of the axon (axon hillock) when the GPSP rises above threshold |
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What does the initial segment have a high density of? |
Voltage-gated sodium channels |
