Final answer:
The cardiovascular system involves the SA node initiating a cardiac impulse that goes through the AV node, followed by the bundle of His and Purkinje fibers, which results in ventricular contraction during systole. The correct option is B.
Step-by-step explanation:
When cardiac impulses reach the junction of the atria and ventricles, the atrioventricular node (AV node) directs the impulses to the ventricles, causing them to contract. This is part of the cardiovascular system. The heart contracts to pump blood during systole and is filled with blood during diastole.
The electrical charge that initiates the heartbeat comes from the sinoatrial (SA) node, causing the atria to contract. The pulse then reaches the AV node, where it pauses briefly before moving through the bundle of His, the right and left bundle branches, and the Purkinje fibers, resulting in the contraction of the ventricles.