The heart's natural pacemaker is located in which structure?

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Multiple Choice

The heart's natural pacemaker is located in which structure?

Explanation:
The heart’s natural pacemaker is the SA node because it is the tissue that automatically generates electrical impulses at the fastest, regular rate, setting the pace for the entire heart. Its cells depolarize spontaneously (pacemaker activity) and fire about 60–100 times per minute in a healthy resting heart. This impulse originates in the upper part of the right atrium near where the superior vena cava enters and then spreads through the atria to coordinate their contraction. From there, the signal moves to the AV node, then along the bundle of His and Purkinje fibers to drive the ventricles. The AV node can take over if the SA node fails, but its intrinsic firing rate is slower, which is why it doesn’t normally set the rhythm. Purkinje fibers and the bundle of His are essential for rapid conduction of the impulse but don’t establish the pace themselves.

The heart’s natural pacemaker is the SA node because it is the tissue that automatically generates electrical impulses at the fastest, regular rate, setting the pace for the entire heart. Its cells depolarize spontaneously (pacemaker activity) and fire about 60–100 times per minute in a healthy resting heart. This impulse originates in the upper part of the right atrium near where the superior vena cava enters and then spreads through the atria to coordinate their contraction. From there, the signal moves to the AV node, then along the bundle of His and Purkinje fibers to drive the ventricles.

The AV node can take over if the SA node fails, but its intrinsic firing rate is slower, which is why it doesn’t normally set the rhythm. Purkinje fibers and the bundle of His are essential for rapid conduction of the impulse but don’t establish the pace themselves.

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