Which scenario is a classic example of a positive feedback loop?

Which scenario is a classic example of a positive feedback loop?

• A. Sweating to cool the body
• B. Regulating blood calcium
• C. Giving birth
• D. Maintaining body temperature

Answer: (C)

A positive feedback loop is a process that amplifies the initial stimulus, creating a self-reinforcing cascade. In giving birth, the starting trigger is the fetus pressing against the cervix. This stimulates the release of oxytocin, which increases uterine contractions. The stronger contractions push the fetus further against the cervix, which releases even more oxytocin and drives even stronger contractions. The cycle keeps amplifying until delivery occurs. Once the baby is born, the stimulus ends and the loop stops, preventing endless escalation. The other scenarios are classic negative feedback examples, where the response works to restore a normal state: sweating to cool the body reduces heat back toward set point, maintaining body temperature involves mechanisms that restore balance, and regulating blood calcium adjusts levels to stay within a narrow range.

A positive feedback loop is a process that amplifies the initial stimulus, creating a self-reinforcing cascade. In giving birth, the starting trigger is the fetus pressing against the cervix. This stimulates the release of oxytocin, which increases uterine contractions. The stronger contractions push the fetus further against the cervix, which releases even more oxytocin and drives even stronger contractions. The cycle keeps amplifying until delivery occurs. Once the baby is born, the stimulus ends and the loop stops, preventing endless escalation.

The other scenarios are classic negative feedback examples, where the response works to restore a normal state: sweating to cool the body reduces heat back toward set point, maintaining body temperature involves mechanisms that restore balance, and regulating blood calcium adjusts levels to stay within a narrow range.