(1) P-wave - what EXACTLY causes the down slope of the P-wave? I understand the P-wave is atrial depolarization, so UPWARD portion/slope of the P-wave makes sense, BUT if depolarization is still occurring during the P-wave, WHY would the slope then go DOWNWARD? I would think that (a voltage drop as indicated by the downward slope on the 2nd half of the P-wave) indicates REpolarization (ie voltage drop), BUT repolarization of the atrium doesn't occur until later during QRS (masked by depolarization of the ventricles). Basically, it seems there should be NO downward slope on P.
(2) QRS - same question: WHY the downward slope (on the second half) if in DEpolarization? (ie since repolarization of vetricles doesn't occur until T)
(3) why the UPward slope on the T-wave if T-wave is REpolarization? (Would think REpolarization would be DOWNward)
Thanks in advance