Homeostasis a change in an organism's environment that produces a response 2. negative feedback small organ attached to the brain that links the nervous system to the endocrine system 3. pituitary gland a homeostatic response to a stimulus that slows or stops the output of a system 4. stimulus the maintenance of a relatively constant state in the internal environment of an organism 5. response any change that occurs inside of an organism that produces a response 6. internal stimulus an action that is caused by a stimulus 7. external stimulus any change that occurs outside of an organism that produces a response