Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart? view available hint(s) which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart? sa node av bundle (bundle of his) av node purkinje fibers?

The correct answer is the SA node or the sinuatrial node. This structure is located in the right atrium near the opening where the superior vena cava enters. The SA node is the part of the heart's conduction system that exhibits automaticity thereby producing impulses without external stimuli. The SA node fires at around 60-100 impulses per minute (same as the normal heart rate of humans at 60-100 beats per minute) These impulses travel to the AV node through 3 pathways; the Bachmann (superior) pathway, the Wenkebach (middle) pathway, and the Thorel (inferior pathway). From the AV node, the impulse will be conducted to the left and right bundle branches and eventually to the Purkinke fibers in which the heart will contract accordingly. 

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