Which of the following is an example of negative feedback ?

Options

A. Sucking reflex
B. Uterine contractions during labor
C. Secretion of CRH in response to ACTH
D. Hair erection due to low body temperature

Answer

To determine which of the following options is an example of negative feedback, let's analyze each option step by step:

1. **Understanding Negative Feedback**:
- Negative feedback is a regulatory mechanism in biological systems where a change in a variable triggers a response that counteracts the initial change, helping to maintain homeostasis.

2. **Analyzing the Options**:
- **Option A: Sucking Reflex**: This reflex is a positive feedback mechanism. When a baby sucks, it stimulates more milk production, which encourages more sucking.
- **Option B: Uterine Contraction During Labor**: This is also a positive feedback mechanism. The contractions push the baby towards the cervix, which stimulates more contractions until delivery occurs.
- **Option C: Secretion of CRH in Response to ACTH**: This is an example of negative feedback. The corticotropin-releasing hormone (CRH) is secreted by the hypothalamus, which stimulates the secretion of adrenocorticotropic hormone (ACTH) from the pituitary gland. In turn, ACTH stimulates the adrenal cortex to produce cortisol. When cortisol levels rise, they inhibit further release of CRH and ACTH, thus maintaining hormone levels within a physiological range.
- **Option D: Hair Erection Due to Low Body Temperature**: This is a physiological response to conserve heat and is not a feedback mechanism.

3. **Conclusion**:
- Based on the analysis, the correct answer is **Option C: Secretion of CRH in Response to ACTH**, as it exemplifies a negative feedback mechanism.