Thank you so much brotherP represents the contraction of the atrial walls, so it rrepresents the excitation wave sweeping ovr the atrial walls in response to which they contract. Q,R and S represent the wave sweeping ovr the ventricular walls which cause them to contract, and T represents the rrecovery of the ventricle walls. there is explaination on dis on Pg 170 in the AS bio book by Mary jones, Dennis taylor, richard fosbery and jennifer gregory.
Well i do have that text book but i think i have the old edition .. caz Pg 170 doesn't talk abt this