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Nervous system

  1. what is an action potential
    • short lasting event in which the membrane potential of a neuron rapidily rises and falls
    • propagates rapidly down axon
    • all or none principle
  2. what is the threshold
    the threshold is membrane potential when action potential begins
  3. what is the membrane potential
    the membrane potential is the potential difference between the interior of a cell and the outside of a cell
  4. if the threshold is not met what happens
    if the threshold is not met the action will not occur
  5. what number is the resting potential
    -70mV  [miliseconds/milivolts]
  6. what number is the threshold
    -55mV
  7. what number is peak of action potential
    +30m
  8. how do you generate an action potential
    • voltage-gated Na and K channels on membrane
    • they are closed at resting potential -70mV
    • depolarisation to threshold -55mV
    • Na channels open, Na enter cells down electrochemical gradient
    • membrane potential +30mV 
    • Na channels clos[inactive], K channels open 
    • K leaves the cell down electrochemical gradient
    • repolarisation -70mV, K channels close 
    • breif hyperpolarisation when the cell reaches -90mV
  9. when do the Na channels open
    when polarisation reaches threshold -55mV
  10. when do the Na channels close
    when membrane potential reaches +30mV
  11. when do the K channels open
    when membrane potential reaches +30mV
  12. when do the K channels close
    when it repolarises to -70mV
  13. why does hyperpolarisation occur
    because K ions continue to leave the cell until all the K channels have closed
  14. the pumping of Na/K ions is an active or inactive process
    active process, requires ATP
  15. Na goes from
    outside to inside
  16. K goes from
    inside to outside
  17. depolarisation is the result of what
    depolarisation results from an influx of Na ions
  18. repolarisation results from
    results from the loss of K ions
  19. what does the Na/K exchange pump do
    returns intracellular + extracellular ion levels back to resting levels
  20. what closes the K gate
    change in polarity
  21. what are nerve impulses
    waves of action potentials
  22. what does Na binding to the pump stimulate
    it stimulates phosphorylation by ATP
  23. what does phosphorylation cause
    it causes the protein to change its conformation, expelling Na+ to the outside
  24. when K binds to the protein what happens
    it triggers the release of the phosphate group
  25. what happens during the loss of P
    the protein restores its original conformation
Author
Claireg05
ID
363050
Card Set
Nervous system
Description
Updated

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