Final answer:
A positive feedback mechanism is the mechanism that brings about an increasing change in the same direction. Childbirth is an example of a normal physiologic process that uses a positive feedback loop.
Step-by-step explanation:
A positive feedback mechanism is the mechanism that brings about an increasing change in the same direction. An example of a normal physiologic process that uses a positive feedback loop is childbirth. During childbirth, the contractions in the uterus cause the secretion of the hormone oxytocin, which further strengthens the contractions. This positive feedback loop continues until the baby is born.