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22 Cards in this Set
- Front
- Back
refractory perdio
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period of time after AP fires during which AP generation cannot be repeated in the same membrane region
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abs refractory period
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no amt of stimulation can trigger AP
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relative refractory period
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second ap can be generated but takes more stimulation (single AP) or yield lower amp (CAP)
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what dose abs refractory period result from
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inactivation of VOLTAGE GATED Na channels
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what is considered abs refractory period for CAP
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all axons within nerve are in their abs refractory period
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electrotonic conduction
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passive spread o membrane potential thru cell
decay over time and distance from point of origin as current leaks out |
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active conduction
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active maintenance of membrane potential as it travels thru cell
means of AP propgation in unmyelinated axons |
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salatory conduction
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action + electrotonic
used in myelinated axons electronic in myelinated parts and actively in unmyelinated parts (nodes) |
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where are most of voltage gated Na and K channels clustered
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nodes of ranvier
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two axon properties that affect conduction speed and efficiency
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axon diameter and myelination
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increasing diameter results in
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lower internal resistance
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myeline results in
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increase membrane resistance
decrease membrane capacitance |
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membrane resistance
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prevents leakage; insulation
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membrane capacitance
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amt of charge captured and stored by patch of membrane
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type A fiber
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large diameter
thick myelin 30-150 m/s motor neuron or sensory neurons |
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type b fiber
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smaller diameter and thinner myelin than A
3-15m/s regulate internal organ and blood vessels (autonomic nervous system) |
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type C fiber
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smallest fiber
no myelin < 2m/s sympathetic innervation and pain signals |
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when is the end of the refractory period
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when all axons are responding again and CAP can reach its original amp again
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what does excitability of nerve refer to
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how readily it generates AP
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what does threshold of nerve depend on
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strength and duration of stimulus
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rheobase voltage
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weakest stimulus that will elicit response from nerve
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chronaxie time
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stimulus duration required to eliciit response at 2x rheobase voltage
measure of nerve excitability |