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Multiple Choice
In the context of cell signaling and electrophysiology, what does the QRS complex represent on an electrocardiogram (ECG)?
A
Repolarization of the atria
B
Repolarization of the ventricles
C
Depolarization of the atria
D
Depolarization of the ventricles
Verified step by step guidance
1
Understand the context of the problem: The QRS complex is a specific part of an electrocardiogram (ECG), which is a graphical representation of the electrical activity of the heart. It is important to know the phases of the cardiac cycle and how they correspond to the ECG waveform.
Recall the key events in the cardiac cycle: Depolarization refers to the electrical activation of heart muscle cells, leading to contraction. Repolarization refers to the process of returning to the resting state after contraction. The QRS complex is associated with ventricular activity.
Identify the components of the ECG waveform: The P wave represents atrial depolarization, the QRS complex represents ventricular depolarization, and the T wave represents ventricular repolarization. Atrial repolarization occurs but is masked by the QRS complex due to its larger amplitude.
Focus on the QRS complex: The QRS complex is a sharp, high-amplitude waveform that corresponds to the rapid depolarization of the ventricles, which is necessary for ventricular contraction and pumping blood to the lungs and body.
Conclude the interpretation: Based on the information above, the QRS complex represents the depolarization of the ventricles, not repolarization of the atria or ventricles, nor depolarization of the atria.