The normal rate for the SA node when the patient is at rest is
A) 40 to 60 beats per minute.
B) 60 to 100 beats per minute.
C) 20 to 40 beats per minute.
D) more than100 beats per minute.

Question

Quizplus · Accepted Answer

The sinus node reaches threshold at a rate of 60 to 100 times per minute.Because this is the fastest pacemaker in the heart,the SA node is the dominant pacemaker of the heart.The AV node has an inherent rate of 40 to 60 beats per minute and the His-Purkinje system can fire at a rate of 20 to 40 beats per minute.Sinus tachycardia results when the SA node fires faster than 100 beats per minute.

The Normal Rate for the SA Node When the Patient