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Maximal ventricular Na+ channel conductance occurs during which phase of the ECG?

A. P wave

B. QRS interval

C. ST interval

D. T wave

E. U wave




A ??


The correct answer is B. Phase 0 of the cardiac muscle action potential (AP) corresponds to the opening of voltage-dependent sodium channels, causing a transient but large increase in sodium conductance during ventricular depolarization. The shape of the QRS complex of the ECG is determined by the spread of the combined phase 0 (depolarization) of all the ventricular muscle of the heart.

The P wave (choice A) corresponds to atrial depolarization.


ohh! my mistake ,
you asked about ventricle and i was thinking about atrial #-o

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