Positive and Negative Feedback

by Greg Crowther

Context

Negative feedback -- the use of effectors to move a regulated variable back toward its setpoint after a perturbation of the variable has been sensed -- is one of the bedrock principles of physiology. In my experience, it can be understood more fully when contrasted with positive feedback, in which a deviation away from a baseline or "setpoint" results in further movement away from that baseline.

Lyrics

Positive feedback promotes a change from a setpoint!
(Setpoint, detector, integrator, and effector!
Negative feedback negates a change from a setpoint!
(Setpoint, detector, integrator, and effector!

Other Files

• MP3 (demo; with Santa and His Elves)

• sheet music

Lesson Plan

Songs like this one can be used during class meetings and/or in homework assignments. Either way, the song will be most impactful if students DO something with it, as opposed to just listening.

An initial, simple follow-up activity could be to answer the study questions below. A more extensive interaction with the song might entail (A) learning to sing it, using an audio file and/or sheet music as a guide, and/or (B) illustrating it with pictures, bodily poses, and/or bodily movements. The latter activity could begin with students identifying the most important or most challenging content of the song, and deciding how to illustrate that particular content.

Study Questions

(1) What are the four components of a negative feedback system?

(2) Give an example of a positive feedback system.

(3) Give an example of a negative feedback system.

(4) How does the melody of this jingle reinforce its message?

(Answers may be found on the answers page.)