Cambridge O Level Biology · Syllabus 5090 · Coordination and Control
Coordination
What is Coordination?
The process by which an organism detects a change in its internal or external environment and produces an appropriate response to it. In mammals the pathway always runs stimulus, receptor, coordinator, effector, response, and is carried out either by electrical impulses along neurones or by hormones transported in the blood.
This definition is part of the Coordination and Control chapter in Cambridge O Level Biology.
Coordination in context
Coordination is how an organism detects a change and produces a useful response to it. Every example in this chapter — pulling a hand off a hot pan, narrowing a pupil, sweating on a hot afternoon, storing glucose after a meal — runs through the same five stages: stimulus → receptor → coordinator → effector → response. Mammals run that chain two ways. Nervous control sends electrical impulses along neurones: fast, precisely targeted, usually short-lived. Hormonal control sends chemicals dissolved in blood plasma: generally slower, more widespread, often longer-lasting. Homeostasis is the job both systems do together — holding internal conditions within narrow limits by negative feedback, in which every correction opposes the change that triggered it.