Question: Polarized

Answer: Simply refers to the heart at rest. No impulse, no stimulation, no contraction, and no measurable activity.

Question: Depolarization

Answer: Another word for the discharge of electrical energy, or the activity of the heart during the impulse that causes contraction, but not the contraction itself. This impulse can be measured by the ECG.

Question: Repolarization

Answer: The electrical recovery of the heart as the cells recharge themselves. It, too, can be measured.

Question: P wave

Answer: The P wave represents the impulse that causes the atria to contract. In medical terminology , the P wave represents the atrial depolarization.

Question: PR interval

Answer: The PR interval indicates the time required for the impulse to travel from the SA-Node, through the atria and through the AV-Node. The PR interval is the lapse of time between the onset of atria contraction to onset of ventricle contraction.