@herstein.jacob what was the decision on this? new card?
Don’t remember this discussion and don’t have access to UW Step 1 anymore…
I keep forgetting haha. @Sameem can you check? Is a new card warranted?
The resting membrane potential of cardiac cells is primarily determined by potassium (K+) ions. These cells have a higher permeability to potassium ions due to the presence of potassium channels, which allows potassium to flow out of the cell more easily, leading to a negative resting membrane potential.
Anyway as far as uworld goes:
Resting membrane potential and action potential
The action potential results from changes in the membrane permeability to K+ and Na+ ions. Depolarization results from massive influx of Na+ through voltage-gated Na+ channels. Repolarization occurs due to closure of voltagegated Na+ channels and opening of voltage-gated K+ channels. K+ ion permeance is highest during the repolarization phase of the action potential. [1380]
Changes in membrane potential occur in response to changes in neuronal membrane permeability to various cellular ions. The more permeable the membrane becomes for a cellular ion, the more that ion’s equilibrium potential contributes to the total membrane potential. [2007]
Card as edited is technically correct, I’d go ahead with this though the effect is more pronounced in cardiac cells
[[FYI nerd-rant: Original card demonstrates a good point, if useless for Step lol.
Cardiac cell resting potential is even more determined by K+ permeability relative to neurons but that’s getting super in the weeds. Equilibrium potential of K+ is around -90 mV, resting potential of cardiac cells as seen in picture is around -85 mV while classically for a neuron its -70 mV (so more K+ relative to Na+ leaks in cardiac cells compared to neurons)]]