Anatomy & PhysiologyQuestion 69 of 100
What is depolarization?
a.The relaxation of cardiac muscle as it returns to its resting state
b.The electrical discharge of cardiac cells that stimulates contraction
c.The flow of blood into the coronary arteries
d.The closing of the atrioventricular valves
Explanation
Depolarization is the rapid electrical change across the cell membrane that triggers mechanical contraction, and it produces the P wave in the atria and the QRS complex in the ventricles. Relaxation and electrical recovery are repolarization. Coronary filling and valve closure are mechanical events of the cardiac cycle, not the electrical activity the EKG records.
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