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.
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
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.
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
Found in muscles, tendons, joints, and pain receptors
Movement stimulates hyperpnea.
Moving limbs, pain, cold water all stimulate breathing in patients with respiratory depression