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kcyanide101
THis answer is confusing. Isn't repolarization the influx of K back into the cell? In that case it QT is prolonged shouldn't it be due to the delayed inward movement of K+????
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lakers2020champs
I think repolarization is the efflux of K+ out of the cell. Remember that the equilibrium potential of K+ is negative. Repolarization means your membrane potential going down and becoming more negative (the action potential is moving down on the graph).
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drdoom
@lakers2020 is right. Re-polarization means the inside and outside of the cell are becoming more POLAR(ized), like Republicans & Democrats. The inside is become more negative, relative to the outside (baseline โ โ70mV).
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drdoom
The spike in an action potential is created by cations(+), usually Na+, rushing into the cell. In the process, the cell moves from โ โ70mV toward zero and then into positive territory; in other words it becomes LESS POLAR(ized) when compared to the outside. The outside and inside become more like each other, which is why it is called DE-POLAR(ization)!
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drdoom
@kcyanide101: โIn that case if* QT is prolonged, shouldn't it โฆโ
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Subcomments ...
Is a case of congenital long QT, there are two principal causes; Romano-Ward (dominant) and Jervell and Lange-Nielsen syndrome, the second one related to deafness (recessive). It's important to remember the relationship of the EKG and the cycle of action potential of the cardiac muscle cell because the QT is correlated with the repolarization (FASE III), similar with the antiarrhythmics, the ones that affect potassium channels (FASE III) are more related with alterations in QT and ventricular arrhythmias.