Which type of feedback mechanism enhances the original stimulus?

• A. Negative feedback
• B. Positive feedback
• C. Adaptive feedback
• D. Cascading feedback

Answer: (B)

The correct answer is positive feedback. This type of feedback mechanism amplifies or enhances the initial stimulus, leading to an increased response. In physiological contexts, positive feedback is often involved in processes that need a definitive outcome or a rapid change, such as during childbirth. For instance, when a baby presses against the cervix, the nerve impulses from this pressure trigger the release of oxytocin. This hormone increases uterine contractions, pushing the baby further against the cervix, which in turn stimulates more oxytocin release—this cycle continues until delivery occurs.

In contrast, negative feedback mechanisms work to counteract a change, returning the system to its set point or equilibrium. This is commonly seen in the regulation of body temperature or blood glucose levels, where deviations from a set point trigger responses that diminish the initial change.

Adaptive and cascading feedback are less commonly referenced in this specific context. Adaptive feedback isn't a standard term in physiology and doesn't specifically enhance the original stimulus. Cascading feedback often refers to a series of events that lead to a significant outcome, but it does not inherently imply enhancement of an original signal in the same way positive feedback does. Therefore, positive feedback is the clear mechanism that enhances the original stimulus.