Reflex Control of Breathing

The Hering-Breuer Inflation Reflex

Receptors located in the visceral pleura, walls of the bronchi and bronchioles.

Lung distention causes stretch receptors to send inhibitory signals to DRG, stopping further inspiration.

In adults active only on large VT (>800 ml)

Regulates rate and depth of breathing during moderate to strenuous exercise

Viewed as a protective mechanism.

Deflation reflex

Sudden lung collapse results in hyperpnea as seen in pneumothoraces.

Head's paradoxic reflex

May maintain large VT during exercise and deep sighs

May be responsible for babies first breaths at birth

Irritant receptors

Subepithelial mechanoreceptors in the trachea bronchi and bronchioles

Stimulated by inhaled irritants or mechanical factors

Cause bronchospasm, cough, sneeze, tachypnea, and narrowing of glottis

These are vasovagal reflexes.

In hospital triggered by

Suctioning, bronchoscopy, endotracheal intubation

Irritation reponse can be anesthetized by instilling lidocaine into the airway through the endotracheal (breathing) tube.

J-receptors

C-fibers - located in the small airways, blood vessels, interstitial tissues between the pulmonary capillaries and alveolar walls

J-fibers - Located in lung parenchyma juxtacapillary

Stimulated by pneumonia, CHF, pulmonary edema

Cause rapid, shallow breathing and dyspnea

Peripheral proprioceptors

Found in muscles, tendons, joints, and pain receptors

Movement stimulates hyperpnea.

Moving limbs, pain, cold water all stimulate breathing in patients with respiratory depression