Match the following columns 

ColumnI 
Column II 

(A) 
P 
(1) 
Electrical excitation of atria 

(B) 
QRS 
(2) 
Repolarisation of ventricles 

(C) 
T 
(3) 
Depolarisation of ventricles 

CODES : 


A 
B 
C 




a) 
1 
2 
3 




b) 
1 
3 
2 




c) 
3 
2 
1 




d) 
3 
1 
2 



Match the following columns 

ColumnI 
Column II 

(A) 
P 
(1) 
Electrical excitation of atria 

(B) 
QRS 
(2) 
Repolarisation of ventricles 

(C) 
T 
(3) 
Depolarisation of ventricles 

CODES : 


A 
B 
C 




a) 
1 
2 
3 




b) 
1 
3 
2 




c) 
3 
2 
1 




d) 
3 
1 
2 



(b)
Electrocardiogram (ECG) It is the graphical recording of electrical changes (in specific sequence) that accompany the cardiac cycle
Though Waller (1887) first recorded the electrocardiogram yet Einthoven (1903) is considered the Father of electrocardiography. It is represented by five waves, named as P, Q, R, S and T
Where
P – Depolarisation of atria. Produced by the activation of SA node
QRS – Depolarisation of ventricle, i.e., spread of impulse through ventricles
PQ – Contraction of atria
QR – Spread of excitation from SA node to AV node
RS – Spread of excitation from AV node to Purkinje fibres (R has the tallest amplitude)
T – Repolarisation of ventricles
Defects in the cardiac structure or functions are recorded in the ECG. Hence, it gives accurate information of atria and ventricles