This study guide on the immune system covers key terminology and the different lines of defense the human body has to protect itself against pathogens. It is available for download with free registration.

The different parts of the immune system and its cell types are explained. Also described are the three kinds of immunity humans have - adaptive, innate and passive - as well as the major types of disorders of the immune system.

Learn how our body works at this personal site from a fourth grade teacher. Colorful graphics and lots of fun facts.

A detailed article about warts in question-and-answer format. Learn why you get them and how you get rid of them.