Modulating Membrane Potential Flashcards
What does Vmem equal?
weighted average of the Nernst potentials for permeant ions
Key difference between Nernst equation and the G-H-K equation?
Nernst = deals with a SINGLE ion species
G-H-K = deals with MUTLIPLE ion species
What is the G-H-K?
Goldman-Hodgkin-Katz Equation
- used for defining equilibrium for multiple ion species
- All ions in the equation must be monovalent
What is Px?
permability of ion ‘x’ relative to benchmark ion
In the G-H-K equation, which concentration ( [x]o or [x]i ) goes on the top of the equation for cations?
[x]o
For anions, where does the [x]o concentration go in the G-H-K equation?
on the bottom
How is the net driving force determined when an ion flows into/out of a cell?
difference between the Nernst equation for that ion and the membrane potential of the cell
If Vmem is more POSITIVE than Nernst for a CATION, that cation will tend to _____ the cell.
Leave
ie= Net flow will be from the cytosol to the ECF
If Vmem is more POSITIVE than Nernst for a ANION, that anion will tend to _____ the cell.
Enter
ie = Net flow will be from the ECF to the cytosol
If Vmem is more NEGATIVE than Nernst for a CATION, that cation will tend to _____ the cell.
Enter
If Vmem is more NEGATIVE than Nernst for a ANION, that cation will tend to _____ the cell.
Leave
Is the Nernst potential for any ion equal to the membrane potential?
NOT usually
T/F: Alterations in ionic gradients only impact some tissues.
False.
Impacts all tissues, but especially excitable tissues
How can the excitability of tissues be accounted for?
physiological alterations in membrane ion permeabilities
Three Types of Membrane Patch-Voltage Clamp Recording Configurations
- cell attached
- excised inside-out
- whole cell = measures all the ion channels in a cell
