Resting Membrane Potential Flashcards
normal potassium concentrations in and out of the cell
- which is higher which is lower
out: ~5 mM
in: ~150 mM
ratio of out/in: 1:30
normal sodium concentrations in and out of the cell
- which is higher which is lower
out: ~150 mM
in: ~12 mM
ratio of out/in: 10:1
what channels have the greatest influence on resting membrane potential
potassium leak channels
what channels have a small influence on resting membrane potential
sodium-potassium ATPase
resting membrane potential is primarily due to permeability of the plasma membrane to _____ ions
potassium
the membrane is permeable somewhat to potassium, but not as much to ____ and _____
sodium and calcium
role of Na+/K+ ATPase
exchange 3 Na+ ions to outside of cell and bring 2 K+ ions into the cell
- maintains concentrations
- requires ATP
potassium leak channels
open all the time; permit mostly unregulated passage of ions
- present in a 100:1 ratio to Na+ leak channels
resting membrane potential of muscle (cardiac/skeletal) cells
-80 mV to -90 mV
resting membrane potential of smooth muscle cells
-60 mV
resting membrane potential of neuron cells
-60 mV to -70 mV
equilibrium potential
membrane potential when electrical and chemical forces are equal, no further movement occurs
(is not the same as resting membrane potential)
electrochemical forces
diffusion forces + electrical forces
driving force
resting membrane potential - equilibrium potential of an ion
- takes into account electrical and chemical forces to predict movement of ions
when [ion]in is greater than [ion]out, the log will be ____
negative
when [ion]in is less than [ion]out, the log will be _____
positive
when [ion]in is equal to [ion] out, the log will be _____
zero
if the driving force for potassium ions is positive, there will be a net ____ of ions
efflux
if the driving force for potassium ions is negative, there will be a net ____ of ions
influx
if the driving force for sodium ions is negative, why is there not an influx of ions?
sodium ions need a signal in order to influx into the cell; at resting they will not enter themselves
normal calcium concentrations in and out of cell
out: 2 mM
in: 0.0002 mM
ratio of out/in: 10,000:1
normal chlorine concentrations in and out of cell
out: 120 mM
in: 10 mM
ratio of out/in: 12:1
normal protein (-) concentrations in and out of cell
out: 0.2 mV
in: 100 mV
ratio of out/in: 1:5,000
with an equilibrium potential of -91 mV, what is the permeability of potassium leaving the cell
80-85%
with an equilibrium potential of +66 mV, what is the permeability of sodium entering the cell
1-2%
with an equilibrium potential of +123 mV, what is the permeability of calcium entering the cell
1%
with an equilibrium potential of -66 mV, what is the permeability of chlorine leaving the cell
10-12%
____ diffusion potential is the main contributor to resting membrane potential
potassium
what is the contribution of Na+ diffusion to resting membrane potential
minimal due to low permeability at rest; 5 mV positive contribution
what is the contribution of Na+-K+ ATP pump to resting membrane potential
minimal direct contribution; 4 mV negative contribution
as extracellular potassium concentration increases, resting membrane potential _____
becomes more positive
as extracellular potassium concentration decreases, resting membrane potential _____
becomes more negative
general equilibrium potential of potassium (K+)
~ -90 mV
general equilibrium potential of sodium (Na+)
~ +60 mV
general equilibrium potential of calcium (Ca2+)
~ 120 mV
general equilibrium potential of chlorine (Cl-)
~ -65 mV
