Biomedical Cybernetics

Ultrashort feedback control (aka as ultra short-loop feedback) is a term from endocrinology denoting a feedback loop, where a hormone inhibits its own secretion in a paracrine or autocrine manner.

It is a characteristic property of ultrashort feedback mechanisms that control is performed without the intermediate step of an additional hormone (which would define short-loop feedback).


  • Brokken-Wiersinga-Prummel loop (auto-inhibition of TSH secretion within thyrotropic feedback control)
  • Ultrashort feedback control of gonadotropin secretion
  • Autoregulation of hypothalamic hormone incretion (e. g. GnRH or Galanin)
  • Control of neurotransmitter release in synapses
  • Regulation of cytokine release in cells of the immune system

Control of hypothalamic CRH secretion is an atypical form. Here, an ultrashort feedback loop exists in form of regenerative feedback, so that in stress-induced allostasis CRH stimulates its own release.

See also[]

  • Short feedback control
  • Long feedback control
  • Ultralong feedback control