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Physiology · Cardiovascular physiology
Sample itemWhat is the primary pacemaker of the normal heart?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
B. Sinoatrial node
The sinoatrial node has the fastest spontaneous depolarization rate and normally sets heart rhythm before impulses travel through the conduction system.
Option by option
A. Purkinje fibres
Purkinje fibres are distal conduction tissue with slower automaticity.
B. Sinoatrial node (correct)
Correct: SA node normally has the highest automaticity.
C. Atrioventricular node
AV node delays conduction but is a slower backup pacemaker.
D. Bundle branches
Bundle branches conduct ventricular impulses rather than initiate normal rhythm.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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