Positive Feedback Loop

A positive feedback loop occurs when the production of a reaction leads to an increase in that reaction. If a system is in homeostasis, a positive feedback loop moves a system further away from the target of equilibrium. It does this by amplifying the effects of a product or event and occurs when something needs to happen quickly. An example of this type of feedback loop in the endocrine system is occurs during childbirth. When labor begins. The baby’s head is pushed downwards, resulting in an increased pressure on the cervix. This stimulates receptor cells to send a chemical signal to the brain, allowing the release of oxytocin. The hormone diffuses to the cervix through the blood, where it stimulates more contractions. These stimulate more oxytocin release until the baby is born.
In this way, the loop brings a system closer to a target of stability or homeostasis. This type of loop is responsible for the stabilization of a system, and the maintenance of a steady, stable state. The response of the regulating mechanism is opposite to the output of the event. An example of this type of feedback loop in the endocrine system occurs with the regulation of blood glucose levels by the pancreas. An influx of glucose, from say a carbohydrate-heavy dinner, triggers the pancreas to produce the hormone insulin. This hormone’s ‘message’ to the body is to take up the extra sugar into cells in order to bring blood sugar back to the target level, or set point. Once enough glucose has been taken up by cells, the pancreas will stop secreting insulin. This feedback loop can help in the opposite situation as well. If blood sugar levels are too low, the pancreas excretes glucagon, which carries the opposite ‘message’ by having cells release their glucose stores so the blood sugar is raised to the set