Match List I with List II.
List I — List II
A. P-wave — I. Beginning of systole
B. Q-wave — II. Repo

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Question

Match List I with List II.
List I — List II
A. P-wave — I. Beginning of systole
B. Q-wave — II. Repolarisation of ventricles
C. QRS complex — III. Depolarisation of atria
D. T-wave — IV. Depolarisation of ventricles
Choose the correct answer from the options given below:

Accepted Answer

Correct Answer: D — A-III, B-I, C-IV, D-IIStep-by-step Solution:A. P-wave → III (Depolarisation of atria): The P-wave is the first positive deflection on the ECG, representing the depolarisation (electrical activation) of both atria as the action potential spreads from the SA node through the atrial myocardium. Atrial depolarisation leads to atrial contraction (atrial systole).B. Q-wave → I (Beginning of systole): The Q-wave is the first negative deflection of the QRS complex. It represents the initial depolarisation of the interventricular septum (from left to right). The onset of the QRS complex (marked by the Q-wave) signifies the beginning of ventricular systole.C. QRS complex → IV (Depolarisation of ventricles): The QRS complex represents the rapid, synchronous depolarisation of the ventricular myocardium (both right and left ventricles). This triggers ventricular contraction. Atrial repolarisation also occurs during this time but is hidden within the larger QRS complex.D. T-wave → II (Repolarisation of ventricles): The T-wave is the positive deflection following the QRS complex. It represents the repolarisation of the ventricular myocardium (return to resting state after contraction). The period between the end of QRS and the beginning of T (ST segment) represents the plateau phase of the ventricular action potential.Key Concepts:Normal ECG sequence: P-wave (atrial depolarisation) → PR interval (AV node delay) → QRS complex (ventricular depolarisation) → ST segment (ventricular plateau) → T-wave (ventricular repolarisation).Each complete P-QRS-T cycle = one cardiac cycle (~0.8 s at 75 bpm).SA node initiates impulse → AV node → Bundle of His → Purkinje fibres → ventricular myocardium.

Match List I with List II. List I — List II A. P-wave — I. Beginning of systole B. Q-wave — II. Repolarisation of ventricles C. QRS complex — III. Depolarisation of atria D. T-wave — IV. Depolarisation of ventricles Choose the correct answer from the options given below:

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Match List I with List II. List I — List II A. P-wave — I. Beginning of systole B. Q-wave — II. Repolarisation of ventricles C. QRS complex — III. Depolarisation of atria D. T-wave — IV. Depolarisation of ventricles Choose the correct answer from the options given below:

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