What triggers the Hering-Breuer reflex?

The Hering-Breuer reflex is initiated primarily by the stimulation of stretch receptors located in the walls of the lungs. When the lungs inflate during inspiration, these receptors sense the stretching of the lung tissue. Once activated, they send signals through the vagus nerve to the medulla oblongata, which in turn inhibits further inhalation to prevent over-inflation of the lungs. This reflex plays a crucial role in regulating the rhythm of breathing and ensuring that the lungs do not expand excessively, thereby maintaining effective ventilation.

While airway obstruction, increased blood CO2 levels, and cellular hypoxia are important physiological factors that can influence breathing and respiratory drive, they do not directly trigger the Hering-Breuer reflex. Instead, these conditions may lead to altered respiratory patterns or rate adjustments but do not involve the stretch receptors in the lungs that specifically activate this reflex mechanism.