Hering-Breuer reflexes

Hering-Breuer reflexes

inflation and deflation reflexes that help regulate the rhythmic ventilation of the lungs, thereby preventing overdistension and extreme deflation. These reflexes arise outside the respiratory center in the brain; that is, the receptor sites are located in the respiratory tract, mainly in the bronchi and bronchioles. They are activated by either a stretching or a nonstretching and compression of the lung; the impulses are transmitted from the receptor sites through the vagus nerve to the brainstem and thence to the respiratory center.

The inflation reflex acts to inhibit inspiration and thereby prevents further inflation. When the lung tissue is stretched by inflation, the stretch receptors respond by sending impulses to the respiratory center, which in turn slows down inspiration. As the expiratory phase begins, the receptors are no longer stretched, impulses are no longer sent, and inspiration can begin again. This is called the Hering-Breuer deflation reflex. It is also believed that in addition to the cessation of impulses from the stretch receptors, there may be an activation of compression receptors which transmit impulses that inhibit expiration, thus allowing inspiration to begin.