Question

Activation of the SA node occurs before the onset of the ? wave. This event is not recorded on the ECG. However, the spread of that impulse throughout the atria (atrial d----) is observed. The first waveform in the cardiac cycle is the P wave.

The beginning of the P wave is recognized as the first abrupt or gradual movement away from the baseline; its end is the point at which the waveform returns to the baseline.

Answer 1

The activation of the SA node occurs before the onset of the P wave on an ECG. This event is not recorded on the ECG, but the spread of the impulse throughout the atria can be observed. The P wave represents atrial depolarization and is the first waveform in the cardiac cycle.

Step-by-step explanation:

The subject of this question is Biology. The question is asking about the activation of the SA node and its relationship to the waveforms observed on an ECG.

Activation of the SA node occurs before the onset of the P wave on an ECG. The P wave represents depolarization of the atria and is the first waveform in the cardiac cycle. The spread of the impulse throughout the atria (atrial depolarization) is observed on the ECG.

Ignoring any typos or irrelevant parts, the main point of the question is to understand the timing and sequence of electrical events in the heart and how they are reflected on an ECG.