neurons threshold levels(exam4)

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rcrchick
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14847
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neurons threshold levels(exam4)
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2010-04-16 18:02:20
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exam4 neurons threshold levels
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exam4 neurons threshold levels
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  1. neurons, like skeletal muscle cells, have threshold levels, therefor the operate in what?
    an "all or none principle"
  2. what does the all or none principle mean for neurons?
    • the neuron transmits a nerve impulse or it does not transmit a nerve impulse
    • a) no such thing as 1/4 or 1/2 strength
  3. what are the 3 types of stimuli?
    • a) threshold stimulus or liminal stimulus
    • b)subthreshold stimulus or subliminal stimulus
    • c)summation of inadequate stimuli
  4. what is the most common stimuli for neurons?
    summation of inadequate stimuli
  5. what is a threshold stimulus or liminal stimulus?
    a single stimulus that is strong enough to initiate a nerve impulse in the post-synaptic neuron
  6. what is a subthreshold stimulus or subliminal stimulus?
    a single stimulus that is too weak to initiate a nerve impulse in the post-synaptic neuron
  7. what is a summation of inadequate stimuli?
    a series of stimuli that are too weak to initiate a nerve impulse b themselves->collectively add together and initiate a nerve impulse in post-synaptic neuron
  8. any one _____-synaptic neuron may be connected to thousands of _____-synaptic neurons. hundreds of them may be active at one time
    • a)post
    • b)pre
  9. whether the post-synaptic neuron initiates a nerve impulse is determined by what?
    comulative effect of all active pre-synaptic neurons
  10. where is cumulative effect expressed at?
    the "axon hillock"
  11. what are the 2 types of stimulation by pre-synaptic neurons?
    • 1.excitatory post-synaptic potential (EPSP)
    • 2. inhibitory post-synaptic potential(IPSP)
  12. what is excitatory post-synaptic postential (EPSP)?
    neurotransmitter that moves the post-synaptic closer to threshold level->more likely to initiate a nerve impulse
  13. what is inhibitory post-synaptic potential(IPSP)?
    neurotransmitter that moves the post synaptic neuron farther from threshold level (hyperpolarizes)-> less likely to initiate a nerve impulse
  14. 1EPSP=1 IPSP

    neuron X has a threshold level= 100 EPSP's, if neuron x recieves 100 EPSP's + 20 IPSP's at same time-> will it initiate a nerve impulse?
    no
  15. 1EPSP=1 IPSP

    neuron X has a threshold level= 100 EPSP's, if neuron x recieves 150 EPSP's + 49 IPSP's at same time-> will it initiate a nerve impulse?
    yes

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