Which of the following is an example of positive feedback?

• A. Regulation of blood glucose levels by insulin
• B. Thermoregulation by sweating to cool the body
• C. The release of oxytocin during childbirth to intensify uterine contractions
• D. Secretion of parathyroid hormone to increase blood calcium when levels are low

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the concept of positive feedback. Positive feedback amplifies or intensifies a physiological process, moving the system further away from its starting point. It is typically used in processes that need a rapid or strong response, such as childbirth.
2. Step 2: Compare positive feedback to negative feedback. Negative feedback works to maintain homeostasis by counteracting changes and bringing the system back to its set point, such as regulating blood glucose levels or thermoregulation.
3. Step 3: Analyze the examples provided in the question. Identify which example involves a process that intensifies or amplifies a response rather than stabilizing it.
4. Step 4: Focus on the example of oxytocin release during childbirth. Oxytocin stimulates uterine contractions, and these contractions, in turn, cause more oxytocin to be released, creating a cycle that intensifies the contractions until childbirth is complete. This is a classic example of positive feedback.
5. Step 5: Confirm that the other examples (regulation of blood glucose by insulin, thermoregulation by sweating, and secretion of parathyroid hormone) are examples of negative feedback, as they work to stabilize physiological conditions rather than amplify them.