Which of the following examples illustrates homeostasis maintained by negative feedback?

• A. Release of oxytocin during childbirth
• B. Generation of nerve impulses
• C. Blood clotting after an injury
• D. Regulation of blood glucose levels by insulin and glucagon

Answer: (D)

Verified step by step guidance

1. Understand the concept of homeostasis: Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. Negative feedback is a mechanism where a change in a physiological variable triggers a response that counteracts the initial change, bringing the variable back to its set point.
2. Analyze the examples provided: Negative feedback mechanisms are characterized by their ability to reverse a change. For example, if blood glucose levels rise, the body will act to lower them, and if blood glucose levels drop, the body will act to raise them.
3. Focus on the regulation of blood glucose levels: When blood glucose levels are high, the pancreas releases insulin, which helps cells absorb glucose and lowers blood glucose levels. Conversely, when blood glucose levels are low, the pancreas releases glucagon, which stimulates the release of glucose into the bloodstream, raising blood glucose levels. This is a classic example of negative feedback.
4. Compare the other examples: The release of oxytocin during childbirth is a positive feedback mechanism, as it amplifies the contractions rather than reversing them. Similarly, nerve impulse generation and blood clotting are also examples of positive feedback mechanisms, as they amplify the initial stimulus.
5. Conclude why regulation of blood glucose levels is the correct answer: The regulation of blood glucose levels by insulin and glucagon fits the definition of negative feedback because it works to restore balance by counteracting changes in blood glucose levels, maintaining homeostasis.