Control of Respiration - Feedback Control

Feedback Control

Receptors play important roles in the regulation of respiration; central and peripheral chemoreceptors, and mechanoreceptors.

• Central chemoreceptors of the central nervous system, located on the ventrolateral medullary surface, are sensitive to the pH of their environment.

• Peripheral chemoreceptors act most importantly to detect variation of the oxygen in the arterial blood, in addition to detecting arterial carbon dioxide and pH.

• Mechanoreceptors are located in the airways and parenchyma, and are responsible for a variety of reflex responses. These include:
  • The Hering-Breuer reflex that terminates inspiration to prevent over inflation of the lungs, and the reflex responses of coughing, airway constriction, and hyperventilation.
  • The upper airway receptors are responsible for reflex responses such as, sneezing, coughing, closure of glottis, and hiccups.
  • The spinal cord reflex responses include the activation of additional respiratory muscles as compensation, gasping response, hypoventilation, and an increase in breathing frequency and volume.
  • The nasopulmonary and nasothoracic reflexes regulate the mechanism of breathing through deepening the inhale. Triggered by the flow of the air, the pressure of the air in the nose, and the quality of the air, impulses from the nasal mucosa are transmitted by the trigeminal nerve to the breathing centres in the brainstem, and the generated response is transmitted to the bronchi, the intercostal muscles and the diaphragm.

In addition to involuntary control of respiration by the respiratory center, respiration can be affected by conditions such as emotional state, via input from the limbic system, or temperature, via the hypothalamus. Voluntary control of respiration is provided via the cerebral cortex, although chemoreceptor reflex is capable of overriding conscious control.