Algonquin College
12.6 - Control of Respiration
Respiration is primarily controlled during its first stage (pulmonary ventilation). The respiratory system does not have its own "pacemaker" like the heart and must rely on the nervous system to send signals to the inspiratory muscles to contract. Respiratory control centres in the brain regulate breathing and make necessary adjustments depending on oxygen demand and carbon dioxide levels in the blood.

Control of breathing rhythm

There are two clusters of neurons (respiratory control centres) in the brainstem that make up the breathing control centre. The respiratory muscles receive input from these centres in the pons and medulla through the phrenic and intercostal nerves.

Medulla respiratory centre
  • Produces rhythmic signals because of a self-exciting respiratory centre
  • Maintains normal breathing (eupnea)
Pons respiratory centre Control of magnitude of ventilation

During exercise, hyperpnea occurs, which involves an increased depth of breathing and a slight increase in breathing rate.

Pulmonary stretch receptors inhibit the inspiratory neurons to prevent over-inflation, which could cause damage to the lungs.

Chemoreceptors in breathing control

Central chemoreceptors Peripheral chemoreceptors
  • Location: Carotid and aortic bodies
  • Sensitive to: Large decreases in oxygen concentration
  • Effect: Increased breathing rate by activation of breathing control centres; overrides voluntary breathing responses