Your immunity to viruses, bacteria, etc. Is described exactly as "<u>defense against disease to identify, destroy, and dispose of disease-causing agents</u>". Therefore your answer is immunity.
The Nervous system releases dopamine and other reward chemicals in response to stimuli. Some such stimuli are addictive substances such as nicotine. When this happens the endocrine system sends bodily messages to relax. Having too much of an artificial substance provoking reward chemicals in your brain results in you not responding or producing enough on your own. Thus how addiction begins to occur. Hope this helps!
