Question

'P' wave of ECG occurs before the

• A. Onset of ventricular contraction
• B. End of arterial contraction
• C. Beginning of atrial contraction
• D. End of ventricular contraction

Answer 1

The correct option is A Onset of ventricular contraction

Atrial systole, normally occurring before ventricular systole, is indicated electrically by the P wave on the ECG. Atrial contraction represented by the P-wave of the electrocardiogram is characterized by electrical depolarization of the atria. Approximately 70 percent of blood goes into the ventricle and the remaining 30 percent is squeezed out through atrial contraction (P-wave).