Anatomy & PhysiologyQuestion 64 of 100
What is the inherent firing rate of the sinoatrial node in a healthy adult?
a.20 to 40 beats per minute
b.40 to 60 beats per minute
c.60 to 100 beats per minute
d.100 to 150 beats per minute
Explanation
The SA node in the upper right atrium is the heart's primary pacemaker and fires 60 to 100 times per minute, which is why normal sinus rhythm is defined by that range. The AV junction fires at 40 to 60 as a backup, and the Purkinje network fires at 20 to 40 as the last resort. A rate of 100 to 150 is a tachycardia, not an inherent pacemaker rate.
Practice all 100 questions free — no signup required.
Related questions on this topic
- A patient's SA node fails completely. Which structure normally takes over, and at what rate?
- What is the inherent rate of the Purkinje fibers, and what does a rhythm at that rate look like?
- What is the correct order of the cardiac electrical conduction pathway?
- Why does the impulse pause briefly at the AV node, and how does that pause appear on the EKG?
- What is depolarization?
- A student asks why an EKG can look normal in a patient whose heart is not pumping effectively. What is the best explanation?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against NHA Certified EKG Technician (CET) Exam · How we review