Negative feedback stabilises internal conditions

By UK A Level Biology · independent study · myAudience

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Negative feedback stabilises internal conditions

Homeostasis maintains internal conditions within workable ranges despite external changes. A receptor detects a variable, a control system coordinates a response, and effectors influence that variable. Negative feedback opposes a deviation rather than reinforcing it.

Regulation does not mean a perfectly fixed value at every moment. Delays, changing demands and opposing responses can produce fluctuations around a range. Temperature control illustrates the principle: responses that increase heat loss differ from responses that conserve or generate heat.

Core temperature and blood pH influence enzyme-mediated processes, while blood glucose supplies a respiratory substrate and contributes to water potential. A useful comparison identifies the regulated variable, the deviation and the direction of the corrective response. Cooling after a temperature rise is negative feedback; a process that amplifies the original rise would be positive feedback, regardless of whether its outcome is described as beneficial.

Worked example: An internal variable rises above its regulated range. An effector lowers it toward the range. Identify the feedback type.

The response opposes the original rise.

Opposing a deviation is negative feedback.

Answer: Negative feedback.

Check your understanding: Is every fluctuation evidence that homeostasis has failed?

Answer: No.

Why: Regulated variables can fluctuate within workable ranges, especially when responses take time.