toxins in the body

Compare and contrast a toxin that affects the nervous system, one that affects the endocrine system, and another that affects the cardiovascular system. What characteristics are shared by these toxins, and what characteristics of these toxins make these toxins vulnerable to toxicity of these specific systems? This paper should be two pages and utilize at least two reliable references in addition to the textbook. One of your references must be a peer-reviewed resource. All sources used, must be referenced; paraphrased and quoted material must have accompanying citations.