heart author" faq

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The conduction system of the heart consists of the following:

1) The Sinus Node in the upper right atrium
2) A branch extending from the Sinus Node to the high left atrium called Bachmann Bundle  
3) The Atrioventricular (AV) Node 
4) The bundle of His, which branches into two major divisions called the left and right bundle branches,which are located in the respective side of the interventricular septum (IV)

5) Cardiac excitation wave pathway animated illustration (see figure 84a above):
starting in the sinus node it spreads over the right atrium as well as to Bachmann's branch into the left atrium; then it goes to the av node on into the His bundle and down into the right and left bundle branches and out laterally to excite each ventricle. Following excitation with depolarization, the conductive tissue repolarizes to be ready for the next pulse.