Hering-Breuer reflex related to `:-`

Options

A. Effect of pH on respiratory centre
B. Effect of `CO_(2)` on respiratory centre
C. Effect of nerve on respiratory centre
D. Effect of temp. on respiratory center

Answer

To solve the question regarding the Hering-Breuer reflex, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Hering-Breuer Reflex**:
- The Hering-Breuer reflex is a protective mechanism that prevents over-inflation of the lungs. It is primarily triggered when the lungs are stretched due to deep or prolonged inhalation.

2. **Location of the Reflex**:
- This reflex is located in the airways, specifically in the bronchi and bronchioles. It involves stretch receptors that detect the degree of lung inflation.

3. **Mechanism of Action**:
- When the lungs are inflated beyond a certain point, stretch receptors send signals via the vagus nerve to the respiratory center in the medulla oblongata of the brain.

4. **Response to the Stimulus**:
- The medulla responds by inhibiting further inspiration, thereby preventing the lungs and alveoli from over-expanding or bursting.

5. **Analyzing the Options**:
- Now, we need to evaluate the options provided:
- Effect of pH on respiratory center: Incorrect, as pH changes influence respiratory rate but are not directly related to the Hering-Breuer reflex.
- Effect of carbon dioxide on respiratory center: Incorrect, while CO2 levels affect respiration, they are not the primary trigger for the Hering-Breuer reflex.
- Effect of nerve on respiratory center: Correct, as the reflex involves the vagus nerve transmitting signals to the brain.
- Effect of temperature on respiratory center: Incorrect, temperature can influence respiration but is not related to the Hering-Breuer reflex.

6. **Conclusion**:
- Based on the analysis, the correct answer is the "effect of nerve on respiratory center," as the Hering-Breuer reflex is fundamentally a neural reflex that prevents over-inflation of the lungs.

### Final Answer:
The Hering-Breuer reflex is related to the **effect of nerve on respiratory center**.

---