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Feedback Systems

Human Biology (Year 12) - Homeostatic Control

Ben Whitten

What are feedback systems?

A feedback system is a circular situation in which the body responds to a stimulus, where the original stimulus is altered, therefore providing "feedback". Feedback systems can either be negative or positive, dependent on the effects of the response.

What are the common features of feedback systems?

The stimulus-response model is a circular model which effectively demonstrates how homeostatic mechanisms work.

Feedback systems have five common features.

  • Stimulus: The change in the environment which causes the operation of the system to occur

  • Receptor: Detects the change (stimulus)

  • Modulator: A control centre which is responsible for processing information received from the receptor and for sending the information to the effector

  • Effector: Carries out a response either counteracting or enhancing the effect of the stimulus

  • Feedback: Achieved through the response to the initial stimulus

Homeostatic mechanisms are controlled by both the nervous system and the endocrine system, as both systems detect when the body is beginning to deviate from its normal balanced state. The nervous system sends electrical messages while the endocrine system sends chemical messengers.

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