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  1. the membrane proteins that create and maintain ion gradients
    active transporters
  2. give rise to selective ion permeability change
    ion channels
  3. ion channels
    membrane proteins that contain specialized structure called a pore that permits particular ions to cross the neuronal membrane
  4. membrane proteins that produce and maintain ion concentration gradients
    active transporters
  5. most important active transporter
    sodium pump
  6. sodium pump
    hydrolyzes ATP to regulate the intracellular concentrations of both sodium and postassium
  7. how are active transporters and ion channels complementary
    transporters create concentration gradients that help drive ion fluxes through open ion channels thus generating electrical signals
  8. properties of channels found by voltage clamp experiments
    • channels must allow ions to move across the membrane at high rates
    • channels had to make use of electrons chemical gradients
    • different channel types had to be capable of discriminating between sodium and potassium
    • must be able to sense voltage drops
  9. what did the patch clamp experiments allow
    to test directly hodgkin and huxleys proposals about the characteristics of ion channels
  10. microscopic currents
    currents flowing through single channels
  11. macrscopic currents
    flowing through large number of channels distributed over a much more extensive region of surface membrane
  12. basis of patch clamp experiments
    • a glass pipette with a very small opening used to make tight contact with a tiny area
    • after using small amount of suction to the back of the pipette
    • this causes a tight seal that do not allow ions to pass through
    • thus all ions that pass through ion channel must go through the pipette
  13. cell attached patch clamp recording method
    when the pipette is attached to the membrane
  14. whole cell recording
    • when the membrane patch within pipette is disrupted by briefly applying strong suction and interior of pipette becomes continuous with the cell cytoplasm
    • allows measurmetns of electrical potential and current from entire cell
  15. inside out path recording configuration
    • retract a pipette that is in the cell attached configuratin causes small vesical of membrane to remain attached to pipette
    • exposing tip of pipette to air allows vesicle to open to yield small path of membrane with its former intracellular suface exposed
    • allows to change intracellular
  16. outside out patch recording configuration
    • if pipette is retracted while in whole cell confiuration a membrane patch produced has its extracellular surface exposed
    • allows study of how channel activity is influenced by extracellular chemical signals
  17. tetrodotoxin
    blocks the macroscopic Na+ current also blocks microscopic Na+ currents
  18. ion selectivity
    able to discriminate between sodium and potassium (can tell between different ions)
  19. voltage gated
    opening is influenced by membrane potential
  20. voltage sensor
    detects the potential across the membrane
  21. inactivation
    prevention of channel to stay open
  22. what causes sodium channel inactivation
    • depolarization
    • both opens and closes
  23. major physiological ions that have voltage gated channels
    • sodium
    • potassium
    • calcium
    • chlorine
  24. How many genes do humans have for voltage gated sodium channels
    • 10
    • rapid inactivation and some channels that do not inactivate
  25. how many genes are there in humans for calcium voltage gated channels
  26. what types of processes do calcium voltage gated channels activate
    release of neurotransmitters
  27. what types of drugs treat anxiety disorders
    drugs that block voltage gated calcium channels
  28. how many potassium channel genes do humans have
    nearly 100
  29. what channels influence the duration and rate of an action potential
    potassium channel closing
  30. what do voltage gated chlorine channels do
    they control excitability, contribute to resting membrane potential and regulate cell volume
Card Set:
2012-03-05 02:55:15

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