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Flashcards

Lab 2 Excitable Cell Membranes

Erika Harkness Human Physiology English 37 cards

Cards in this deck (37)

  1. 1voltage difference across the cell membrane at restresting membrane potential difference (resting potential)
  2. 2Higher K concentration is locatedICF (intracellular fluid)
  3. 3Higher Na concentration is locatedECF (extracellular fluid)
  4. 4resting membrane potential difference is usually ranges from-40 to -80 mV
  5. 5steps in excitable cellstimulus
    graded potential
    action potential
    exocytosis of ACh from axon terminal
  6. 6depolarization of soma and dendrites via influx of Nagraded potential
  7. 7gated Na channels lining the soma and dendrites that respond to stimulusmembrane receptors
  8. 8examples of things that stimulate membrane receptorsACh, other chemical ligand, mechanical force on cell membrane
  9. 9strength of graded potential is determined bythe strength of the stimulus
  10. 10strength of graded potential is affected by1. number of membrane receptors opened
    2. length of time membrane receptors stay open
    3. amount of Na allowed to influx
  11. 11accumulation of Na from multiple graded potentialssummation, graded potential can summate
  12. 12no distinct ____________ in soma, takes time for Na to dissipate or be pumped back out after influx,repolarization process
  13. 13can have multiple _________ from single graded potential and/or summationaction potentials
  14. 14from multiple graded potentials over short period of time from the same origintemporal summation (separated by time)
  15. 15from multiple graded potentials arriving at about the same time from different originsspatial summation (separated by space)
  16. 16depolarization along length of axonaction potential
  17. 17voltage required to initialte action potentialthreshold
  18. 18connection between soma and axonaxon hillock
  19. 19opens at -55 mV, allows influx of Na from the ECF causing _________Voltage gated Na channel
    activation gate, depolarization
  20. 20closes at +30 mV, does not respond to voltage again after closing (under normal circumstances) takes time to resetVoltage gated Na channel
    inactivation gate
  21. 21channel starts opening at -55mV, allows efflux of K from ICF causing ________ eventually leading to ____________Voltage gated K channel
    repolarization
    hyperpolarization
  22. 22only has an activation gate, slower to open, timed to be open when cell reaches +30mVvoltage gated K channel
  23. 23"all or nothing" due to nature of the channelsaction potential
  24. 24TF: can have a gradient potential without an action potentiatrue
  25. 25time during which another action potential cannot be initiatedabsolute refractory period
  26. 26Absolute refractory period starts at ________ when voltage gated ____ opensthreshold
    Na
  27. 27Absolute refractory period continues while ________ of voltage gated Na channel is ______inactivation gate
    closed
  28. 28keeps action potentials as separate, distinct depolarizations rahter than allowing axon to depolarize for extended period of timeabsolute refractory period
  29. 29time during which it is more difficult than normal to initiate an action potentialrelative refractory period
  30. 30during the relative refractory period the cell is __________ so it takes a greater amount of Na from the soma to push the axon hillock to thresholdhyperpolarized
  31. 31frequency or number of action potential codes for strength of signal or strength of stimulusfrequency coding
  32. 32transduction rate is affected byaxon diameter
    myelination
  33. 33walls cause resistance to flow, more distance from walls equals faster rate, therefore larger axons allow for faster transductionaxon diameter
  34. 34prevents ion leakagemyelination
  35. 35if Na leaks back out along the axon...Na inside the axon decreases, the diffusion rate decreases and transduction decreases
  36. 36With myelination...fewer gated channels are involved (Na diffuses through myelin covered sections, less Na required to be moved for process, more efficient)
    fast pain (myelinated)
    slow pain (non-myelinated)
  37. 37nerve segment is bundle of axons, generally not possible to seperate a single one to be tested (except for squid giant axon) the sum of action potentials travelling on parallel axons at the same time, will vary in strength as number of axons depolarizing at one time changescompound action potential (artificial)

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Human Physiology Flashcards on Lab 2 Excitable Cell Membranes, created by Erika Harkness on 23/06/2015.
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Erika Harkness
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