Which activity gets your heart pumping more: using the computer, climbing the stairs, jumping rope, running, or walking? Youngsters take a heart rate reading after 30 seconds, one minute, and three minutes of each activity. The handout...

Are spiders related to crabs? Study the order of arthropods with a reading selection about animal diversity. It provides details about each class within the order, as well as vivid pictures and explanatory charts. 

Access Excellence offers detailed information, including diagrams and photos, about the anatomy of the heart and its central role in the circulatory system.

This comprehensive study guide covers the main terms and concepts needed for a unit on the circulatory system.

This thorough resource examinces the several types of circulatory systems and provides drawings of these systems in molluscs, arthropods, and the earthworms.

The circulatory system and how it functions are explained. An interactive diagram shows how blood flows through the heart. Disorders of the heart and the circulatory system are also described.

Describes the anatomy of a fish's circulatory system and how the blood circulates in a fish.

Describes the parts of a rat's circulatory system and how the blood circulates in a rat.

Describes the parts of a pig's circulatory system and how its blood circulates. Circulation in a pig fetus is also described as it has differences.

Overview of the cardiovascular system with labeled diagrams and reviews of the heart, torso, arm, leg, and blood, available through the links on the right.

This site from the University of Manitoba provides an explanation of the purpose and structure of the respiratory and circulatory systems. Follow the link to the images.

William Harvey, doctor during the Age of Enlightenment, challenged mainstream understanding of the heart and the circulation of blood. Read about his early education and his scientific inquiry.

A very good site about the circulatory system of a bird. It is reader friendly, and includes a fair amount of information. Good diagram of the circulatory system.

A very good description of the blood and circulatory systems of mammals and the important role that blood plays in the physiology of animals.

This thorough resource provides listing of ten unique characteristics peculiar to the cardiovascular system along with an examination of these ten factors individually.

An extensive page on the circulatory system in general. Scroll down to section 49.3 and you will find a simple comparison of the reptilian system to the other vertebrae systems.

How does blood supply your body with the nourishment it needs? This site focuses on systemic circulation. Learn more about this fascinating part of your body when you check out this resource.

This site from LookD.com provides information about bony fish circulation systems. The article is very brief, only one paragraph in length, but worth checking out on the subject.

An overview of the evolution of modern mamallian circulation. This is a good site since it puts the circulation found in reptiles in perspective. Compares it to systems in fish and mammals.

This general overview of the arthropod phylum, which includes insects and arachnids, looks at such topics as body symmetry, appendages, movement, respiratory and nervous systems, and reproduction.

Causes of heart failure, signs and characteristics of heart failure, pathologic conditions resulting in heart failure, and more are the topics addressed in this thorough resource.

This site from the Department of Chemistry at the Washington University provides a deetailed study of the role of hemoglobin in blood physiology. The article is somewhat in-depth, complete with pictures, charts, and a bibliography.

A complete reference tool that serves as an illustrated resource for presenting information on heart conditions. Content includes information on what they are, how the heart works, diagnosis, congenital defects, treatment, and long term...

Article on arrhythmias with information about the heart's pacemaker.