Glossary
positive feedback
Positive feedback is a loop in which the response amplifies the change that triggered it, so a process runs to a finish instead of settling.
Positive feedback is a loop in which the response makes the change bigger, so the value moves further from where it started. It cannot hold anything steady, which is why it appears only where a process has to finish quickly. Labor is the standard case: pressure on the cervix triggers oxytocin release, oxytocin strengthens the contractions, and the stronger contractions press harder — the loop runs until delivery, and then the trigger is gone. Blood clotting is the other: an activated factor activates more of its own kind, so a small injury produces a clot that stops growing once the damaged surface is covered. Both are useful only because something outside the loop ends them. Left running with no brake, the same shape is what a fever that keeps climbing looks like.
Taught in
Related terms
- negative feedback — Negative feedback is a loop in which the response reverses the change that triggered it, bringing the value back toward its set point.
- receptor — A receptor is the structure that detects a change — the sensor of a feedback loop, reporting temperature, pressure, chemistry or stretch.
- effector — An effector is what carries out a feedback loop's response — a muscle that contracts or a gland that secretes.
- homeostasis — Homeostasis is the maintenance of a stable internal environment while conditions outside the body change — a loop that keeps correcting, not a fixed state.
Source: The anatomy and physiology guide in this course, whose organ and tissue descriptions follow the US National Cancer Institute's SEER Training Modules and MedlinePlus consumer health pages. Both are US federal government material, not subject to copyright in the United States. The definition above is written for this course in our own words. (SEER Training Modules accessed 2026-10-26; definition written 2026-10-27)