Definition for View source for Hering-Breuer inflation reflex

This is a reflex triggered to prevent over-inflation of the lungs. Pulmonary stretch receptors present in the smooth muscle of the airways respond to excessive stretching of the lung during large inspirations.

Once activated, they send action potentials through large myelinated fibers of the paired vagus nerves to the inspiratory area in the medulla and apneustic area of the pons. In response, the inspiratory area is inhibited directly and the apneustic area is inhibited from activating the inspiratory area. This inhibits inspiration, allowing expiration to occur.

The Hering–Breuer inflation reflex ought not be confused with the deflation reflex discovered by the same individuals, Hering and Breuer. The majority of this page discusses the inflation reflex; the deflation reflex is considered separately at the end.