Question

In an ECG pattern, the P wave is caused by

Select one:
a. depolarization of ventricular muscle fibers.
b. repolarization of the ventricular muscle fibers.
c. repolarization of the atrial muscle fibers.
d. depolarization of atrial muscle fibers.
e. none of the above.

Answer 1

The P wave in an ECG pattern is caused by the depolarization of atrial muscle fibers, leading to atrial contraction and precedes the QRS complex of ventricular depolarization.

Step-by-step explanation:

In an ECG pattern, the P wave is caused by the depolarization of atrial muscle fibers. When the atria depolarize, they contract and pump blood into the ventricles. This event is distinct from the QRS complex, which represents the depolarization of ventricular muscle fibers, and the T wave, which indicates the repolarization of ventricular muscle fibers. Atrial repolarization is not visible on the ECG because it occurs at the same time as the QRS complex and is thus masked by the much stronger electrical signals of ventricular depolarization.