In which direction does the electrical impulse of the heart travel?

The correct direction of the electrical impulse in the heart is from the sinoatrial (SA) node, located in the right atrium, to the atrioventricular (AV) node and then downwards through the Bundle of His, into the left and right bundle branches, ultimately reaching the Purkinje fibers spread throughout the ventricles. This sequence takes the impulse primarily from the right side of the heart to the left side, and it moves towards the apex and upward through the ventricular walls, thus follow the path to initiate contraction starting from the right side to the left side of the heart.

Understanding the pathway of this impulse is vital for recognizing how the heart coordinates its contractions to maintain effective blood flow. The other options do not accurately describe the established direction of impulse conduction in the cardiac electrical system.