PositiveFeedback Positive feedback can be identifiedas a mutualistic interaction, in other words the output affects the input and/orthe input affects the output, it is a cycle, and is commonly referred to as aloop. Positive feedback loops are very rare, yet necessary for life. Thismechanism does not directly contribute to the maintenance of homeostasis, it actuallypushes the system further away from its equilibrium due to its reinforcing nature.I used the term ‘reinforcing’, because instead of opposing the unfavorable changesoccurring in the homeostatic environment like negative feedback, it enhancesthem; the initiating stimulus will cause more of that same stimulus. Constantactivity of this mechanism could have detrimental effects. Typically, there issome sort of definitive endpoint, often described as an explosive event.
A physiologicalexample of positive feedback is the secretion of oxytocin during childbirth,this hormone is produced by the hypothalamus and is responsible for coordinatedcontractions of smooth muscle in the uterus. Oxytocin is also responsible formilk letdown during lactation, and it has some involvement in bonding behavior.As mentioned previously, the releasing of this hormone promotes uterinecontractions, and being that it is regulated by the positive feedbackmechanism, these contractions in turn promote more oxytocin to be released,thus causing stronger uterine contractions. The oxytocin continues to increaseand the contractions continue to get more fierce, that is until the ‘explosiveevent’ occurs, which in this case will be the actual delivery of the child.Once the child has been expelled from the womb, oxytocin secretion ceases, stoppingthe uterine contractions. Though rare, and potentially very dangerous, positivefeedback is a much appreciated aspect of life. In its absence there would be noblood clotting, action potentials, or inducing of childbirth.
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