QRS Complex & Ventricular Depolarisation — NEET Biology
✅ Asked in NEET 2020The QRS complex in a standard ECG represents: (NEET 2020)
The QRS complex in a standard ECG represents: (NEET 2020)
Answer & NCERT explanation
Correct answer: A — Depolarisation of ventricles
QRS complex represents ventricular depolarization - the electrical activity that triggers ventricular contraction. It's the largest wave in ECG and indicates ventricular systole beginning. Atrial depolarization is P-wave, ventricular repolarization is T-wave. NCERT emphasizes QRS as ventricular electrical activity.
Read more NCERT concept on the PYQ
The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole.
The QRS complex on an ECG represents the electrical depolarisation of the ventricles, which triggers ventricular muscle contraction and marks the start of systole. Students often confuse QRS with atrial activity or mistake it as repolarisation instead of depolarisation. The key distinction: Q-R-S together specifically show ventricular depolarisation, NOT atrial events (that's P wave). Remember that depolarisation precedes contraction—QRS comes first, then mechanical contraction follows. This is frequently tested because understanding ECG waves directly links to cardiac physiology and pressure changes during the cardiac cycle.
What does NCERT say about QRS complex represents depolarisation?
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