Final answer:
The QRS complex in an ECG represents the depolarization of the ventricles for heart contraction and the repolarization of the atria, which is masked by ventricular activity. It precedes the rise in arterial blood pressure, signaling ventricular contraction.
Step-by-step explanation:
The QRS complex is a component of the electrocardiogram (ECG) that signifies the depolarization of the ventricles, which is the process whereby the heart's ventricles prepare to contract and pump blood to the lungs and body. This depolarization requires a stronger electrical signal due to the larger size of the ventricular cardiac muscle. Additionally, the QRS complex includes the repolarization of the atria, although it is not visible on an ECG because it is masked by the more prominent depolarization activity of the ventricles. The ventricles begin to contract as the R wave peaks, coinciding with the subsequent increase in arterial blood pressure, specifically the systolic blood pressure.Arterial blood pressure […] varies with each part of the heartbeat, with the systolic pressure reaching its maximum shortly after the QRS complex. This marks the contraction of the ventricles and the pumping of blood into circulation.