with a specific function.  As these chemicals, cells, tissues, and organs work together, it is understandable that harmful changes at one level in the body alter functions at other areas of the body.  The body maintains stability and function even though drastic changes take place in the environment by a process known as homeostasis.

The body is precisely arranged into several levels of organization.  The highest level is that of organ systems, each which is composed of specific organs.  Within the organs are various types of tissues