Final answer:
After the atria contract, the electrical impulse is briefly delayed at the AV node, then transmitted through the bundle of His to the Purkinje fibers, causing the ventricles to contract and pump blood.
Step-by-step explanation:
After the atria contract, the electrical impulse reaches the atrioventricular (AV) node where it pauses, allowing the atria to finish emptying blood into the ventricles. Following the pause, the impulse travels through the bundle of His into the left and right bundle branches, spreading through the interventricular septum and into the Purkinje fibers.
This network conducts the impulse from the apex of the heart upwards, prompting the ventricles to contract which is known as ventricular systole, marking the start of the powerful phase of the heartbeat where blood is expelled from the heart into the circulation. This pause allows the atria to empty their contents into the ventricles before the ventricles pump out the blood.