Mechanisms for maintaining homeostasis in the body generally involve negative feedback. However, there are also a few positive feedback mechanisms.
In a positive feedback mechanism, the stimulus increases the response and as a result as long as the stimulus is continued the response is amplified progressively.
Examples of positive feedback mechanism in the body include:
- Clotting of blood
- Uterine contractions during labour
During labour, a hormone called oxytocin stimulates contractions of the uterus. These contractions force the baby’s head into the cervix of the uterus. Stretch receptors situated in the cervix are stimulated by the entry of the baby’s head and cause more oxytocin to be released. This causes further contractions in the uterus and maintains labour. Once the baby is born, the stretch receptors are no longer stimulated and release of oxytocin ceases.