Quiz 4 Flashcards
Nernst Equation
Ex=RT/zF ln([x]out/[X]in)
Common Nernst Potentials
Ek= -93
Ena= +61
Ecl= -75
Nernst Potential
membrane potential that a single ion would produce if the membrane was permeable to only that ion
Synonyms for Nernst Potential
equilibrium potential
reversal potential
equilibrium potential
membrane potential at which a given ion net flux is 0
reversal potential
membrane potential at which a given ions flux reverses from inward to outward
if Ex=Vm
no net flow
if Ex>Vm
reverses flow
if Ex<Vm
flows with gradient
equilibrium potentials set boundaries
ceiling- Ena
floor- Ek
Negative Vm inside moves ____ ions ___
positive
in
depolarization
changing membrane potential to be more positive
repolarization
returning membrane potential towards resting potential
hyperpolarization
changing membrane potential to be more negative
GHK Equation
V= RT/F ln Pk[k]out+Pna[na]out+Pcl[cl]in/ Pk[k]in+Pna[na]in+Pcl[Cl]out
weighted average of Ex for each ion
What does GHK predict?
the potential that results from the contribution of all membrane-permeable ions
At rest Vm is close to ___
Ek, because the membrane is mostly permeable to K
Ions with ____ permeability have ____ influence on V
greater
greater
The membrane is in ____ not equilibrium.
steady state
steady state
unchanging state that remains so only by constant input/output
At rest Vm=?
-70
Can change the membrane potential by…
changing the permeability of different ions
