Final answer:
The wave that is not part of one heartbeat on an ECG tracing is B. V. Components such as the P wave, QRS complex, and T wave are present on an ECG, but there is no V wave in the cardiac cycle as represented on an ECG.
Step-by-step explanation:
The correct answer to the question is B. V, as all other options (P, Q, R, T) are components of a normal electrocardiogram (ECG) tracing of a heartbeat. The P wave represents atrial depolarization, the QRS complex indicates ventricular depolarization, and the T wave reflects ventricular repolarization. There is no V wave in the ECG.
An ECG tracing is used to reflect the electrical activity of the heart and is composed of several different waves that relate to specific cardiac events. The P wave signifies the depolarization of atria, which leads to the contraction of the atria. The QRS complex represents the depolarization of ventricles, which is necessary for the ventricles to contract and pump blood throughout the body. Finally, the T wave indicates the repolarization of the ventricles, setting up the heart for the next cycle. It is important to note that the repolarization of the atria is masked by the larger QRS complex and is not visible on the ECG as a separate wave.