What characterizes a positive feedback system in physiology?

A positive feedback system in physiology is characterized by its ability to amplify a change in a variable, pushing the system further from its starting condition rather than stabilizing it. This is particularly evident in processes where an increase in one factor leads to a further increase in that same factor. A classic example of this is during childbirth, where the release of oxytocin stimulates uterine contractions. As contractions increase, more oxytocin is produced, leading to even stronger contractions until the birth occurs.

This mechanism contrasts with negative feedback systems, which are designed to minimize changes from a set point and stabilize internal conditions. In positive feedback, rather than dampening changes, the system actively encourages greater deviations until a specific goal is achieved, at which point the process might cease. Thus, the nature of positive feedback is distinctly about enhancement and continuation of the response rather than moderation or stabilization.