When resting, blood goes from the heart to the lungs and back in about six seconds. An animation of the heart starts simply by showing blood flow through the two halves. It builds in complexity slowly over the course of five slides,...

Check Steve's cardiovascular health before he starts filming his dangerous wildlife special. Following the activity, read more about the heart, and then take a quick quiz to check for understanding.

Take an interactive tour of the human heart. Click on each part of the illustration to read more information about each structure.