Which of the following is an example of a negative feedback loop maintaining body temperature?

• A. Regulation of body temperature
• B. Giving birth
• C. Milk ejection
• D. Onset of labor

Answer: (A)

Negative feedback keeps body temperature within a narrow range by counteracting any change from the normal set point. The hypothalamus acts like a thermostat, sensing deviations from this point. If temperature rises, the body responds with sweating and skin vasodilation to lose heat, bringing temperature back down. If temperature falls, vasoconstriction and shivering generate or conserve heat to raise it back toward the set point. This opposing action is what defines a negative feedback loop and why regulating body temperature is a textbook example. The other options illustrate processes where the response amplifies the initial stimulus (positive feedback), such as labor contractions intensifying with stretch, or milk ejection in response to suckling.