Question

The first half of the P wave is recorded when the electrical impulse that originated in the ________ node stimulates the right atrium and reaches the AV node.

The downslope of the P wave reflects stimulation of the left ___________, thus the P wave represents atrial ___________ and the spread of the electrical impulse throughout the right and left atria.
The atria contract a fraction of a second after the P wave begins. The atria begin to _______ at the same time as the ventricles depolarize.
A waveform representing atrial repolarization is usually not seen on the ECG because it is small and buried in the QRS complex.

Answer 1

The P wave on an ECG represents atrial depolarization originating from the SA node, leading to atrial contraction, with relaxation beginning during ventricular depolarization as indicated by the QRS complex.

Step-by-step explanation:

The first half of the P wave is recorded when the electrical impulse that originated in the SA node stimulates the right atrium and reaches the AV node. The downslope of the P wave reflects stimulation of the left atrium, thus the P wave represents atrial depolarization and the spread of the electrical impulse throughout the right and left atria. The atria contract a fraction of a second after the P wave begins. The atria begin to relax at the same time as the ventricles depolarize. A waveform representing atrial repolarization is usually not seen on the ECG because it is small and buried in the QRS complex.