Question

1. Humans can survive if the heartbeat originates from which two locations in the heart? (Include the inherent rate that would originate from both.)

2. In a normal ECG wave tracing, why do you not see atrial repolarization?

3. What would it mean on an ECG if there was no p wave? (What would this type of arrythmia be called?)

Answer 1

1. The SA node is the heart's natural pacemaker. The SA node fires at a normal rate of 60–100 beats per minute (bpm)

The AV node slows the impulses from the SA node, firing at a normal rate of 40-60 bpm,

2.The wave of atrial repolarization is relatively small in amplitude, so it is masked by  much larger ventricular-generated QRS complex.

3.The P wave represents the depolarization of the left and right atrium and also corresponds to atrial contraction. If P wave is absent than It means the top two chambers of the heart, are not able to start an electrical impulse, propagate that electrical impulse, or be electrically stimulated, and therefore are not moving or contracting .

The type of arrythmia would be atrial fibrillation