Action Potentials Flashcards
Normal ionic concentrations:
Na and Cl outside high ~ 150
K outside low ~ 5
Active transport: How many ions moves at Na-K ATPase
3 NA ions out
2 K ions in
Neuron membranes use ___ to move ions
pumps, transporters and channels
what is chemical gradient
different concentratoins of ions in and out of cell
what is equilibrium potential
when electrical gradient balances the chemical gradient
what equation is used for equilibrium potential
Nernst equation
Nernst equation:
E = RT/zF ln Co/Ci
resting membrane potential
Na permeability is low
K permeability is high
which equation calculates resting potential
Goldman
Resting potential ____ mV
-50 to -70
Cell membrane is made more negative on the inside
hyperpolarization
Cell membrane is made less negative (or more positive) on the inside
depolarization
Total current through channels depends on
driving force (fast) on the ions
Specialized membrane channel proteins
that pass ions at high rate when open
voltage-dependent channels
how many subunits make a potassium voltage channel
4 a and b subunits make one channel
Play an important role in development of resting potential (some are open at resting potential)
potassium K channels voltage-dep
Important for repolarization after action potential , in hyperpolarization and in neuronal inhibition
potassium K channels voltage-dep
K pottasium channels are blocked by
TEA- tetraethylammonium
which region is the voltage sensor in Na voltage channels
S4 region
how many alpha helices do Na channels have
S1-S6
Important for rising phase of action potential
voltage Na channel
what can causes inactivation (open channel blocked by inactivation particle)
Maintained depolarization of Na channels
Recovery from Na inactivation requires
repolarization for a few ms
Na channels are block by
local anesthetics (lidocaine, procaine) or animal toxins (tetrodotoxin)
