question_answer 26)

  Which of the following correctly explains a phase/event in cardiac cycle in a standard electrocardiogram? (a) QRS complex indicates atrial contraction. (b) QRS complex indicates ventricular contraction (c) Time between S and T represents atrial systole. (d) P-wave indicates beginning of ventricular contraction

Answer:

                  (b)QRS Complex QRS wave (complex) begins after a fraction of second after the P wave. It begins as a small downward deflection (Q) and continuous as a large upright (R) and triangular wave, ending as downward wave (S) at its base.                 This represents ventricular depolarization (ventricular contraction). Thus, the other options are wring.