| 11. | Without any nervous stimulation, the SA node would establish a sinus rhythm of approximately 100 bpm.
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| 12. | In contrast, the SA node in normal state can fire at 60-100 beats per minute.
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| 13. | In the absence of extrinsic neural and hormonal control, cells in the SA node will rhythmically discharge.
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| 14. | It occurs when the rate of depolarization of the SA node falls below the rate of the AV node.
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| 15. | A junctional escape complex is a normal response that may result from excessive vagal tone on the SA node.
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| 16. | This can disrupt the electrical pacemaker function of the SA node, and can result in sick sinus syndrome.
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| 17. | Normally, all the foci will end up firing at the SA node rate, not their intrinsic rate.
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| 18. | Both of these can cause an increased distance of internodal conduction from the SA node to the AV node.
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| 19. | Image showing the cardiac pacemaker or SA node, the normal pacemaker within the electrical conduction system of the heart.
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| 20. | However, the other firing frequencies are slower than the one of the SA node ( as seen above ).
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