What is the normal intrinsic firing rate of the SA node?

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Prepare for the MyMichigan Telemetry Monitoring and Management Test. Utilize flashcards, multiple choice questions, each with hints and explanations. Master your exam!

Multiple Choice

What is the normal intrinsic firing rate of the SA node?

Explanation:
The SA node is the heart’s natural pacemaker, and its cells fire spontaneously at a baseline rate when external autonomic input is minimal. That intrinsic firing rate is about 60–100 beats per minute, which is why this range is considered normal for the SA node. In everyday life, resting heart rate can sit around the lower end of this range due to parasympathetic (vagal) tone, while sympathetic activation can push the rate higher. If the SA node’s pacing becomes unavailable, slower pacemakers in the AV node or Purkinje system take over, producing slower rates (around 40–60 or 20–40 bpm, respectively). Thus, 60–100 bpm best reflects the SA node’s intrinsic firing rate.

The SA node is the heart’s natural pacemaker, and its cells fire spontaneously at a baseline rate when external autonomic input is minimal. That intrinsic firing rate is about 60–100 beats per minute, which is why this range is considered normal for the SA node. In everyday life, resting heart rate can sit around the lower end of this range due to parasympathetic (vagal) tone, while sympathetic activation can push the rate higher. If the SA node’s pacing becomes unavailable, slower pacemakers in the AV node or Purkinje system take over, producing slower rates (around 40–60 or 20–40 bpm, respectively). Thus, 60–100 bpm best reflects the SA node’s intrinsic firing rate.

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