Editing Negative feedback (section)

=== Biology ===
{{See also|Counterregulatory hormone|Homeostasis}}
[[Image:ACTH Negative Feedback.svg|thumb|250px|Control of endocrine hormones by negative feedback.]]

Some biological systems exhibit negative feedback such as the [[baroreflex]] in [[blood pressure]] regulation and [[erythropoiesis]]. Many biological processes (e.g., in the [[human anatomy]]) use negative feedback. Examples of this are numerous, from the regulating of body temperature, to the regulating of blood [[glucose]] levels. The disruption of feedback loops can lead to undesirable results: in the case of [[Blood sugar level|blood glucose levels]], if negative feedback fails, the glucose levels in the blood may begin to rise dramatically, thus resulting in [[Diabetes mellitus|diabetes]].

For hormone secretion regulated by the negative feedback loop: when gland X releases hormone X, this stimulates target cells to release hormone Y. When there is an excess of hormone Y, gland X "senses" this and inhibits its release of hormone X. As shown in the figure, most [[endocrine]] [[hormone]]s are controlled by a [[physiology|physiologic]] negative feedback inhibition loop, such as the [[glucocorticoid]]s secreted by the [[adrenal cortex]].  The [[hypothalamus]] secretes [[Corticotropin-releasing hormone|corticotropin-releasing hormone (CRH)]], which directs the [[pituitary gland|anterior pituitary gland]] to secrete [[ACTH|adrenocorticotropic hormone (ACTH)]].  In turn, ACTH directs the adrenal cortex to secrete glucocorticoids, such as [[cortisol]].  Glucocorticoids not only perform their respective functions throughout the body but also negatively affect the release of further stimulating secretions of both the hypothalamus and the pituitary gland, effectively reducing the output of glucocorticoids once a sufficient amount has been released.<ref>Raven, PH; Johnson, GB. ''Biology'', Fifth Edition, Boston: Hill Companies, Inc. 1999. page 1058.</ref>