Negative feedback mechanisms serve to do what?

• A. Amplify the original stimulus
• B. Shut off the original stimulus or reduce its intensity
• C. Create a new set point
• D. Require external input to function

Answer: (B)

Negative feedback keeps the body's conditions steady by opposing a change. When a parameter moves away from its normal range, sensors detect the deviation and trigger responses that counteract it, reducing or turning off the original stimulus. This brings the variable back toward its usual value, and the response diminishes once balance is restored. A classic example is temperature regulation: if the body gets too hot, cooling mechanisms like sweating and vasodilation work to lower it; if it gets too cold, warming mechanisms such as shivering and vasoconstriction kick in to raise it. This opposing action is what maintains homeostasis.

Amplifying the stimulus would push the change further, which isn’t how negative feedback works. Creating a new set point isn’t the typical outcome of negative feedback, though temporary shifts can occur in special situations. And while some systems can involve external inputs, the defining feature is the automatic counteraction to restore balance, not dependence on outside prompts.