Body Fluids and Circulation
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:
A-III, B-I, C-IV, D-II
ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle.
The P-wave represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria.
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 T-wave represents the return of the ventricles from excited to normal state (repolarisation). The end of the T-wave marks the end of systole.