Demonstrates how a heart actually functions as two pumps in one. Scenes at an amusement park show the effects of activity on the heart. Scenes of the internal heart are matched with still drawings and animations that depict the heart's valves, muscle, and pacemaker. The effects of diet and exercise on the heart are mentioned. Accessibility options on the DVD are: (1) audio description, (2) English subtitles, (3) English subtitles in a black box, (4) closed captions.