The Circulatory System - A Better Way
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.
www.a-better-way.com/systems/8_1.html   reviews

The Heart and the Circulatory System
Description of the heart and blood vessels complemented by several illustrations.
www.accessexcellence.org/AE/AEC/CC/heart_anatomy.html   reviews

Introductory Anatomy - Circulatory System and Blood
Lecture notes from an introductory human biology course. Contains no images but describes the function of the vessels, valves, blood, etc.
www.leeds.ac.uk/chb/lectures/anatomy6.html   reviews