Arrange these elements of the intrinsic conduction system in the order that a depolarizing impulse travels during a normal heartbeat. rank from first to last.
do not overlap any tiles.
av node
bundle branches
internodel pathways
sa node
purkinje fibers
av bundle

SA Node

Inter-nodal Pathways

AV Node

AV Bundle

Bundle Branches

Purkinje Fibers

The SA nodes functions first for setting pace for the heart, then the inter-nodal pathway make link b/w SA and AV node. AV node is site of delay when contraction of atria occurs. AV bundle is the mean of electrical link b/w atria and ventricle. The conveying of impulse to the inter-ventricular septum occurs through bundle branches, while conveying of impulse throughout and along the walls of ventricle occurs through Purkinje fibers.

the answer is:

carbon dioxide