Certified EkG technician (CET) Practice Exam

The P wave represents which physiological process?

1. Atrial repolarization

2. Atrial depolarization

3. Ventricular contraction

4. Ventricular filling

The correct answer is: Atrial depolarization

The P wave on an electrocardiogram (EKG) specifically represents atrial depolarization, which is the process whereby the atria of the heart contract in response to electrical impulses. This depolarization occurs when the sinoatrial (SA) node, the heart's natural pacemaker, sends out an electrical signal that causes the muscle cells in the atria to become excited and initiate contraction. This process is crucial because it contributes to filling the ventricles with blood before they contract. Understanding this waveform is essential for interpreting EKGs, as it provides insight into the electrical activity associated with the atrial phase of the cardiac cycle. The characteristics of the P wave, such as its shape and duration, can also offer important information regarding atrial health and function. In contrast, the other options pertain to different aspects of cardiac physiology. Atrial repolarization is reflected in the QRS complex rather than the P wave; ventricular contraction is associated with the QRS complex, not the P wave; and ventricular filling occurs primarily during diastole, which is not represented by the P wave. Each of these processes is distinct and serves an important function in the overall mechanics of the heart but does not relate to the specific representation