Which of the following is the best example of a negative feedback mechanism in homeostasis?

• A. The increase in heart rate during exercise to supply more oxygen
• B. The clotting of blood to prevent excessive bleeding
• C. The release of insulin to lower blood glucose levels
• D. The release of oxytocin during childbirth to increase contractions

Answer: (C)

Verified step by step guidance

1. Understand the concept of homeostasis: Homeostasis is the body's ability to maintain a stable internal environment despite changes in external conditions. Negative feedback mechanisms are processes that counteract changes, bringing the system back to its set point.
2. Identify the characteristics of negative feedback: Negative feedback mechanisms work to reverse a change in a controlled condition. When a variable deviates from its normal range, negative feedback mechanisms activate to bring it back to the desired level.
3. Analyze each example: Consider how each example functions in the body. The increase in heart rate during exercise is a response to increased demand for oxygen, not a reversal of a change. Blood clotting is a positive feedback mechanism, as it amplifies the response to injury.
4. Focus on insulin release: The release of insulin in response to high blood glucose levels is a classic example of negative feedback. Insulin helps lower blood glucose levels, counteracting the initial increase and restoring balance.
5. Consider oxytocin release: The release of oxytocin during childbirth is a positive feedback mechanism, as it enhances contractions to facilitate delivery, rather than reversing a change.