Negative feedback is the process by which the outputs tend to reduce the inputs, which causes the system to stabilize. It is found in many functions that organisms carry out on a daily basis, most notably homeostasis. Negative feedback can be seen during the menstrual cycle, during days 5-10 oestrogen levels slowly rise, this increase causes the release of the hormones FSH and LH to be inhibited. Also in low concentrations progesterone has a negative feedback effect on FSH, this means that more follicles cant be stimulated during the second half of the cycle.
Moreover, once levels of progesterone are high, it inhibits the production of the hormone LH, meaning the corpus luteum is no longer stimulated to make progesterone, so it could be said that progesterone effectively turns itself off unless pregnancy occurs. Negative feedback can also be witnessed in childhood growth, the pituitary gland produces thyroid stimulating hormone, which is used to create the materials necessary to grow. The amount of TSH produced is controlled by negative feedback. Homeostasis, or the maintenance of a constant internal environment is also mainly controlled by negative feedback.
For example, thermoregulation works because if the temperature falls below normal the body will initiate a response such as shivering, however as the temperature returns to normal the corrective mechanism will be reduced. Similarily negative feedback also controls Osmoregulation, if osmoreceptors detect change in the concentration of the blood, for example it may be too high the hormone ADH is released which targets the distal convulated tubule, causing it to become more permeable to water so that more is reabsorbed into the blood, reducing the concentration.
Negative feedback is also a crucial part of controlling blood glucose levels, for example if the islets of Langerhans detect a fall in blood glucose levels, the alpha cells release glucagon, which in turn activates the conversion of glycogen to glucose within cells so it can be released in to the blood. As the levels of glucose in the blood increase the amount of glucagon released will decrease until it reaches normal. Negative feedback is an essential process that helps regulate many of the processes that enable us to live.