HeringBreuer

The Hering-Breuer reflex, also known as the Hering-Breuer inflation reflex, is a mammalian respiratory reflex described by Ewald Hering and Josef Breuer in the late 19th century. It involves the lungs’ stretch receptors and plays a role in regulating the depth of breathing to prevent overinflation.

Mechanism and pathway: The reflex is mediated by slowly adapting pulmonary stretch receptors located in the walls of the airways. When the lungs inflate during inspiration, these receptors are activated and send signals via the vagus nerve to the medullary respiratory centers. The afferent input inhibits inspiratory neurons, leading to termination of inspiration and the onset of expiration. A deflation-related component, sometimes referred to as the deflation reflex, has been described in some species, but its presence and significance in humans are less clear.

Significance and scope: The Hering-Breuer inflation reflex is most prominent in infant mammals and is considered less influential in healthy adult humans under normal resting breathing. In adults, central and peripheral chemoreceptors, along with other neural circuits, primarily regulate breathing, while the Hering-Breuer mechanism contributes as a protective check against excessive lung inflation and helps shape tidal volume during various breathing demands or forced breathing.

Clinical and research notes: The reflex is a classic topic in physiology and respiratory biology, illustrating how peripheral lung receptors feed back to central respiratory control. Its exact role in day-to-day human respiration is nuanced, with greater relevance in neonatal physiology and in certain experimental or pathological contexts.