Question

place the steps in the movement of electrical impulses through the conducting system in order, from start to finish.

1. atrial contraction begins. there is a 100 - millisecond delay at the av node.
2. the impulse is distributed by the purkinje fibers and relayed throughout the ventricular myocardium. atrial contraction is completed, and ventricular contraction begins.
3. depolarization spreads across the atrial surfaces and reaches the av node.
4. the impulse travels along the interventricular septum within the av bundle and the bundle branches to the purkinje fibers and, via the moderator band, to the papillary muscles of the right ventricle.
5. sa node depolarization and atrial activation begin.

Explanation:

The normal cardiac conduction pathway starts with the SA node (sino - atrial node) depolarizing (step 5). Then depolarization spreads across the atria to the AV node (step 3). After that, atrial contraction begins with a delay at the AV node (step 1). The impulse then travels along the interventricular septum (step 4) and is finally distributed by the Purkinje fibers (step 2).

Answer:

5, 3, 1, 4, 2