4.4.A—Explain how positive and negative feedback helps maintain homeostasis

Explain how positive and negative feedback helps maintain homeostasis.

• Organisms use feedback mechanisms to maintain their internal environments in response to internal and external changes.
  • i. Negative feedback mechanisms maintain homeostasis by reducing the initial stimulus to regulate physiological processes. If a system is perturbed or disrupted, negative feedback mechanisms return the system back to its target set point. These processes operate at the molecular, cellular, and organismal levels.
  • ii. Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved further away from the initial set point. Amplification occurs when the stimulus is further intensified, which, in turn, initiates an additional response that produces system change.