Glossary
effector
An effector is what carries out a feedback loop's response — a muscle that contracts or a gland that secretes.
An effector is the part of a control loop that does something about the change: a muscle that contracts, or a gland that releases what it makes. In temperature control the effectors are the sweat glands and the smooth muscle in the skin's blood vessels — one adds evaporation, the other shifts blood flow — and in the cold the effector is the skeletal muscle that shivers. In glucose control the effectors are the cells that take glucose out of the blood and the liver that releases it back. The effector sits downstream of the decision, which is what separates it from the receptor: the receptor reports, the control center compares, the effector acts. A loop in which the effector works and the reading still never returns is the shape a disease takes from the inside, and naming the failed element is the point of asking about all three.
Taught in
Related terms
- receptor — A receptor is the structure that detects a change — the sensor of a feedback loop, reporting temperature, pressure, chemistry or stretch.
- 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.
- 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.
- 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.
- nervous tissue — Nervous tissue carries electrical signals: neurons generate and conduct them, and glial cells insulate, feed and support the neurons.
- reflex arc — A reflex arc is the pathway a reflex travels — receptor, sensory neuron, a synapse in the CNS, motor neuron and effector — without waiting for the brain.
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)