How does blood move through the heart — and how does the heartbeat coordinate it? This 3D animation uses an anterior cross-section to show the sequence clearly: The atria collect incoming blood from the body and lungs The ventricles contract in a powerful motion to eject blood Four valves prevent backflow and ensure unidirectional movement The entire sequence is powered by the heart's built-in conduction system This view gives rare insight into one of the body’s most critical functions. Based on