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Multiple Choice
Which structure is considered the primary pacemaker of the heart under normal physiological conditions?
A
Atrioventricular (AV) node
B
Bundle of His (atrioventricular bundle)
C
Purkinje fibers
D
Sinoatrial (SA) node
Verified step by step guidance
1
Understand that the heart's rhythm is controlled by specialized cardiac muscle cells that generate electrical impulses, known as pacemaker cells.
Identify the main structures involved in the heart's conduction system: the Sinoatrial (SA) node, Atrioventricular (AV) node, Bundle of His, and Purkinje fibers.
Recognize that the primary pacemaker is the structure that initiates the heartbeat by generating the fastest and most regular electrical impulses under normal physiological conditions.
Recall that the SA node, located in the right atrium, has the highest intrinsic firing rate compared to the AV node, Bundle of His, and Purkinje fibers, making it the primary pacemaker.
Conclude that because the SA node sets the pace for the heart's rhythm, it is considered the primary pacemaker under normal conditions.