How does the brain regulate breathing rate?

The brain regulates breathing rate primarily by the concentration of carbon dioxide in the blood. The brain, particularly the brainstem, contains central chemoreceptors that closely monitor the levels of carbon dioxide (CO2). When CO2 levels rise, indicating that the body is producing more of it due to metabolic activity or that it is not being expelled efficiently, the brain signals the respiratory muscles to increase the breathing rate. This increase in breathing helps to expel more CO2, thus restoring balance to the blood gas levels.

While oxygen levels in the blood and other factors like body temperature or heart rate can influence breathing, the most immediate and critical response for regulating ventilation is through CO2 concentration. High levels of CO2 lead directly to an increase in the drive to breathe, demonstrating the brain's prioritization of maintaining proper blood gas levels.