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<p>produces action potentials, setting the rhythm of the heart (<a href="page.php?w=sinus_rhythm">sinus rhythm</a>), and so is known as the heart's <a href="page.php?w=cardiac_pacemaker">natural pacemaker</a>. The rate of action potentials produced (and therefore the <a href="page.php?w=heart_rate">heart rate</a>) is influenced by the <a href="page.php?w=nerves">nerves</a> that supply it.</p>

<p><big>Structure</big></p>
<p>The sinoatrial node is a crescent-shaped structure located in the subepicardial layer of the right atrium. The size of the SA node varies</p><p>
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