Answer: Depolarization of the atria, just before atrial contraction.
- A The brief pause between atrial and ventricular contraction
- B Depolarization of the atria, just before atrial contraction
- C Repolarization of the ventricles after contraction
- D Depolarization of the ventricles, just before ventricular contraction
Correct answer: B. Depolarization of the atria, just before atrial contraction
Explanation: The P wave in an ECG represents the electrical depolarization of the atria, which precedes and triggers atrial contraction.
A single ECG cycle: the P wave marks atrial depolarisation (contraction signal), the large QRS complex marks ventricular depolarisation, and the T wave marks ventricular repolarisation (recovery) before the next cycle begins.
Concept context
Blood, lymph, the heart, the cardiac cycle, blood pressure, and ECG. High NEET weightage.