Anatomy & PhysiologyCâu 65 / 100
A patient's SA node fails completely. Which structure normally takes over, and at what rate?
a.The Purkinje fibers at 60 to 100 beats per minute
b.The AV junction at 40 to 60 beats per minute
c.The bundle branches at 100 to 120 beats per minute
d.The atrial muscle at 20 to 40 beats per minute
Giải thích
The AV junction is the secondary pacemaker and assumes control at 40 to 60 beats per minute when the SA node fails, producing a junctional escape rhythm with absent or inverted P waves. The Purkinje network fires only at 20 to 40 and takes over if the junction also fails. Bundle branches conduct rather than pace at a fast rate, and general atrial muscle is not a designated escape pacemaker.
Luyện miễn phí toàn bộ 100 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- What is the inherent firing rate of the sinoatrial node in a healthy adult?
- 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?
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