In an average lifetime, the heart beats more than two and a half billion times, without ever pausing to rest.

Color illustration of the structures of the heart along with a description of its function. Also includes information about the blood and its components, heart disease, and preventive health maintenance.

Description of the heart and blood vessels complemented by several illustrations.

Lecture notes from an introductory human biology course. Contains no images but describes the function of the vessels, valves, blood, etc.