Flashcards in Membrane Electrophysiology: Resting Membrane Potential Deck (18):
What is a membrane potential?
separation of charges across plasma membrane
What are the key ions involved in membrane potential?
Ca2+, Na2+, K+, Cl-
When is a resting membrane potential established?
when cell is not sending signals
Why is a resting membrane potential important?
in general, is important for transport processes involving movement of charges
What is the general RMP range for skeletal, cardiac, and nerve cells?
-60 to -90 mV
What factors contribute to the RMP?
- intracellular anions
- Na+/K+ pump (indirect contribution)
- diffusion potential of permeable ions
What ion will have the greatest contribution/effect on the RMP?
the ion with greatest permeability
net movement of charge across cell membrane
Define diffusion potential.
potential difference across cell membrane due to concentration difference of an ion, dependent on size of concentration gradient.
What forces act on an ion?
- concentration (chemical) force
- electrical foce.
it is the sum/difference of these two forces that determine the net movement of the ion
Define electrochemical equilibrium
when chemical and electrical forces acting on an ion are equal and opposite causing zero net diffusion of ion.
Define equilibrium potential.
diffusion potential (mV) at which the concentration gradient's promotion of diffusion is opposed
- size based on ions charge and distribution
- magnitude is based on concentration gradient
What is the function of the Nernst equation?
to predict the equilibrium potential for any concentration gradient of an ion - aka what the membrane potential would be for the ion to be at electrochemical equilibrium
What is the rate of ion diffusion depend on?
1. external and internal concentration of ions
2. transmembrane voltage
3. permeability of ion
Define membrane conductance.
the ease/ability for ion to pass through membrane. (if channels are open, conductance increases)
What are the three main classifications of ion channels?
What ion has the greatest effect on the resting membrane potential: Na+ or K+?