Stimulus for Hering – Breuer’s reflex of Respiration is
**Core Concept**
The Hering-Breuer inflation reflex is a vital mechanism that regulates breathing, preventing overinflation of the lungs. It involves the detection of lung inflation by stretch receptors in the bronchi, which then send signals to the brainstem to inhibit further inhalation.
**Why the Correct Answer is Right**
The reflex is mediated by the Hering-Breuer inflation receptors in the bronchi, specifically the J-receptors and C-fibers. When the lungs are inflated, these receptors are activated, sending signals to the dorsal respiratory group in the medulla oblongata. This results in the inhibition of the inspiratory neurons, leading to a decrease in the depth and rate of breathing.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the stimulus for the Hering-Breuer reflex. The correct stimulus is lung inflation, not lung deflation.
**Option B:** This option is incorrect because it refers to the chemoreceptor trigger zone, which is involved in the regulation of breathing in response to changes in blood pH, CO2, and O2 levels, not lung inflation.
**Option C:** This option is incorrect because it is a type of lung disease, not a stimulus for the Hering-Breuer reflex.
**Clinical Pearl / High-Yield Fact**
A key clinical correlation is that patients with respiratory diseases, such as chronic obstructive pulmonary disease (COPD), may have an impaired Hering-Breuer reflex, leading to hyperinflation of the lungs and respiratory failure.
**Correct Answer:** D. Lung inflation.