BIOL 223 Membrane Potentials - 3

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christophertkennedy
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113259
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BIOL 223 Membrane Potentials - 3
Updated:
2011-10-30 20:27:29
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anatomy physiology membrane potentials
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Study Cards for Membrane Potentials BIOL 223 CSN
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  1. If the local potential brings the cell to threshold, the result in a(n):
    action potential
  2. Define threshold.
    the minimum change in potential needed to initiate an action potential
  3. What is the threshold potential for a neuron?
    -60 mV
  4. True or False: Everytime a cell reaches threshold, an action potential results.
    True
  5. The concept that states that if a cell does not reach threshold, there can be no action potential is the:
    all or none principle
  6. What type of ion movement causes the depolarization of cells?
    influx of positively charged sodium ions
  7. How does membrane potential change during depolarization?
    • it becomes more "positive" in charge
    • -70 mV to +20 mV
  8. How does membrane potential change during repolarization?
    • it becomes more negative
    • +20 mV to -70 mV
  9. What type of ion movement will occur during repolarization?
    outflux of positively charged potassium ions
  10. What type of ion movement occurs during hyperpolarization?
    outflux of positively charged potassium ions
  11. How does membrane potential change when the cell hyperpolarizes?
    • it becomes more negative
    • -70 mV to -90 mV
  12. How will hyperpolarization affect the ability of the cell to reach threshold.
    it will make it harder to reach threshold
  13. On an action potential graph, what two things occur when the ligand-gated channels open?
    • small amount of sodium comes in
    • cell moves towards threshold
  14. On an action potential graph, what two things occur when the voltage-gated channels open?
    • large amounts of sodium comes in
    • cell depolarizes
  15. At +20 mV, the apex of the action potential graph, what two things occur?
    • sodium channels close
    • potassium channels open
  16. On an action potential graph, what two things occur as the cell repolarizes?
    • potassium leaves the cell in large amounts
    • as potential approaches threshold, K gates close
  17. The period of time in which an excitable cell can't generate a second action potential in response to a normal stimulus is known as the:
    refractory period
  18. What two things are occuring during the refractory period?
    • reestablishment of ion gradients
    • potential returns to resting value
  19. True or False: A relative refractory period can generate a second response if the stimulus is strong enough.
    True
  20. Define Excitatory Postsynaptic Potential (EPSP).
    small depolarization of the membrane which brings cell closer to threshold
  21. Define Inhibitory Postsynaptic Potential (IPSP).
    a small hyperpolarization of the membrane which brings the cell further away from threshold
  22. Will an EPSP inhibit or stimulate the postsynaptic cell.
    stimulate the postsynaptic cell
  23. Will an IPSP inhibit or stimulate the postsynaptic cell?
    inhibit the postsynaptic cell
  24. Multiple stimuli applied at the same location, but at different times, will result in which type of summation?
    temporal summation
  25. Two or more stimuli applied at the same time at different locations will result in which type of stimulation?
    spatial summation
  26. Which type of summation is quicker, temporal or spatial?
    spatial summation
  27. Which will result in summation, EPSP or IPSP?
    EPSP
  28. If a neuron has a threshold value of -60 mV, will a local potential of -65 mV result in an action potential?
    no, it will not
  29. If a neuron has a threshold value of -60 mV, will a local potential of -59 mV result in an action potential?
    yes, it will
  30. What cellular function returns the ion gradients after the depolarization and repolarization of a cell membrane?
    the sodium/potassium pump

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