feedback mechanisms are required to maintain stable conditions in the body.wen the body conditions become unfavourable, info is sent to the control centre (usually brain) to correct this condition.
An example of a feedback mechanism in humans would be the increase in heart rate and respiratory rate which occurs in response to increased exercise or other increased muscle cell activity.
sweating maintains a stable body temp then the evaporation of this perspiration returns the body to its original temperature. (detection, control,response/ counteract,feedback) hence the correct temp is retored so info is sent to the brain once more to stop the cooling mechanism
sorry not 2 sure about negative feed, will look it up tho. good luck!