question_answer

The diagram given here is the standard ECG of a normal person. The P-wave represents the:

A)  Contraction of both the atria

B)  Initiation of the ventricular contraction

C)  Beginning of the systole

D)  End of systole

Correct Answer: A

Solution :

 The P-waves represent the electrical excitation (or depolarization) of the atria, which leads to the contraction of both the atria. The QRS complex represents the depolarization of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole.