Illustration of hormonal regulatory cycles, or endocrine axis, that are hierarchically structured and predominantly adhere to negative feedback inhibition. Those are necessary to control synthesis and secretion of hormones. Given a metabolism parameter and the current actual hormone concentration, the concentration is adjusted to the desired value. The hypothalamus produces releasing hormones (liberines) and inhibiting hormones (statines) that either stimulate or inhibit the release of pituitary hormones, which again have an effect on peripheral target cells, but also give feedback to superordinate centers.
