ECG

P wave = Atria contract (atrial depolarization)
🟢 QRS complex = Ventricles contract (ventricular depolarization)
🟢 T wave = Ventricles relax (ventricular repolarization)

Step-by-Step Breakdown:

1⃣ P wave – The SA node fires, causing atria to contract (depolarization).
2⃣ QRS complex – The signal reaches the ventricles, making them contract (depolarization).
3⃣ T wave – The ventricles relax and reset (repolarization).

💡 Key ECG Facts for Exams:

• If the P wave is missing ➝ Atria aren’t contracting properly.

• If the QRS complex is too wide ➝ Ventricular contraction is slow or abnormal.

• If the T wave is abnormal ➝ Ventricular repolarization is off, possibly due to potassium imbalance.