Physiological Positive Feedback Mechanisms

Abstract

In positive feedback mechanisms, the response to a stimulus does not stop or reverse it but instead keeps the sequence of events going up. At first glance, this would appear to be a counter to the principle of homeostasis, since a positive feedback loop has no obvious means of stopping. Not surprisingly, therefore, the positive feedback is less common in nature than the negative one. A positive feedback mechanism can be harmful, as in case of fever that causes metabolic changes pushing it to be higher. However, in some instances, the body uses this mechanism for its advantage. A good example of significant positive feedback is the childbirth. Ovulation, coagulation, platelet aggregation, inflammation and shock are other instances in which the positive feedback plays a valuable role.