How significant is the role of oxygen in the regulation of respiration?

Oxygen plays a minor role in the regulation of respiration primarily because the body relies more heavily on levels of carbon dioxide (CO2) to control breathing rate and depth. The central chemoreceptors located in the brain are predominantly sensitive to changes in CO2 levels, as an increase in CO2 leads to an increase in acidity (lower pH) in the cerebrospinal fluid, which directly stimulates the respiratory centers to increase ventilation.

While oxygen levels are monitored by peripheral chemoreceptors in the carotid and aortic bodies, these receptors only trigger respiratory changes when oxygen levels fall to critically low levels. This mechanism is more of a backup system compared to the primary regulation conducted by CO2 levels, which means that under normal circumstances, oxygen has a relatively minor role in the continuous regulation of respiration.

This understanding highlights why the minor role of oxygen is considered appropriate, as the body is more attuned to managing the levels of CO2 to maintain homeostasis and ensure efficient gas exchange.