The Resting Membrane Potential Flashcards
Define membrane potential
magnitude of electrical charge inside the cell relative to the extracellular solution = mV
How can you measure MP?
microelectrode penetrates cell membrane, conducting solution, mV taken
Generating MP requires 2 factors, what are they?
Asymmetric distribution of ions across PM and selective ion channels
Which ion dominates the membranes permeability the most?
K+, due to open K+ channels
Describe the electrical vs the chemical gradient for K+
Towards inside: electrical gradient for K+, +ve attracted to –ve anions
Towards outside: chemical (diffusion) gradient for K+, high to low conc
Which equation can be used to calculate the equilibrium potential?
Nernst equation
Which ions are higher in conc inside?
K+ and A- (all other anions)
What will increasing the permeability for a particular ion do to the equilibrium potential for that ion?
Move it closer to the equilibrium potential
What is the Nerst equation at 37C?
61/valency x log10 x [K]o/[K]i
What is the resting MP of a nerve?
-70mV
What is the resting MP of a cardiac cell?
-90mV
What is selective permeability?
Different cells have different channels present allowing different amounts of ions in/out: ion channels
What is equilibrium potential?
MP at which the ion will be in equilibrium, given the extra/intra concs
If the membrane is selectively permeable to one ion where will MP be?
Equilibrium potential (nernst equation)
Which ions are higher in conc outside?
Na+, Cl-, Ca2+