Which conduction system component has the fastest intrinsic firing rate?

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Multiple Choice

Which conduction system component has the fastest intrinsic firing rate?

Explanation:
The most rapid intrinsic firing rate comes from the primary pacemaker tissue, which is the sinoatrial (SA) node. It normally fires about 60–100 impulses per minute, setting the heart’s pace. Because it has the highest automaticity, it drives the rhythm under normal conditions. If the SA node should fail, the next fastest automaticity is the AV node, which tends to pace at roughly 40–60 bpm, and if that also fails, the Purkinje fibers can take over at around 20–40 bpm, but at a much slower rate. The atrial myocardium isn’t a specialized pacemaker and doesn’t determine the normal pace. Therefore, the SA node is the component with the fastest intrinsic firing rate.

The most rapid intrinsic firing rate comes from the primary pacemaker tissue, which is the sinoatrial (SA) node. It normally fires about 60–100 impulses per minute, setting the heart’s pace. Because it has the highest automaticity, it drives the rhythm under normal conditions. If the SA node should fail, the next fastest automaticity is the AV node, which tends to pace at roughly 40–60 bpm, and if that also fails, the Purkinje fibers can take over at around 20–40 bpm, but at a much slower rate. The atrial myocardium isn’t a specialized pacemaker and doesn’t determine the normal pace. Therefore, the SA node is the component with the fastest intrinsic firing rate.

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