Resting Membrane Potential Flashcards
what is membrane potential?
the voltage or charge difference across cells
inside of cell is negative
outside of cell is more positive
what controls the magnitude of the membrane potential?
the number of charges on both sides of the membrane
the greater the number of charges, the greater the potential
what are some general characteristics of ion channels?
-channels are selective
-some open in absence of stimuli (ungated/leaky)
-others open to specific stimulus
what is the chemical driving force?
the concentration gradient across the membrane
what is the electrical driving force?
separation of charges causes an electrical gradient across the membrane
what combination makes up the electrochemical gradient?
chemical and electrical driving force
what does the equilibrium potential refer to?
the diffusion potential (electrical force) that exactly balances or opposes the tendency for diffusion of an ion down its concentration gradient
when is an ion in equilibrium?
when the chemical and electrical driving forces are equal and opposite
magnitude of potential is directly proportional to magnitude of concentration gradient
what is the equilibrium potential for K?
-90 mV
what is the equilibrium potential for Na?
+65 mV
what is the nernst equation?
E ion = (60/z)log([ion out]/[ion in])
what is the potential difference of an ion if the ion cannot cross/is impermeable?
0
what is resting membrane potential?
the difference that exists across the membrane of excitable cells at steady state
what ion has the greater influence on the RMP?
K+ –> has the highest permeability and conductance
what is ohm’s law/goldman’s equation?
g(k)E(K) + g(Na)E(Na)
E(m) = ——————————–
g(k) + g(Na)
