Mixing up the sensor, control center and effector
- The idea
- Predict
- See it
- Why
- Check
The idea
“The part that reacts to a change, like a sweat gland, must be what sensed it.”
You get hot, sweat shows up, and it looks like the glands felt it. The detecting and comparing happen out of sight.
The short version
The mistake: The part that reacts to a change, like a sweat gland, must be what sensed it.
What's actually true: A sensor detects the change, a control center compares it with a set point, and an effector acts.
- The stimulus is the change itself, like body temperature rising. It isn't part of the loop.
- A sensor detects the change. The control center, often in the brain, compares it with a set point.
- Effectors, like muscles and glands, carry out the response. In negative feedback, it reverses the change.
- One organ can do two jobs. The hypothalamus senses and compares temperature.
On the exam: Name each part by its verb. The sensor detects, the control center compares, the effector acts.