Read up on Homeostasis (p. 209 – 211, and also check index for additional pages that may be relevant). Finish the handouts on experimental design/scientific method and homeostasis.
If you have time, please watch the Bozeman Science Preview – Homeostasis video. There are many other videos on the subject, as well, so feel free to browse and check them out.
Another edition of our textbook is available here.