Which factor is most significant in regulating respiration at rest?

The regulation of respiration at rest is primarily influenced by the levels of carbon dioxide (Pco2) in the blood. When Pco2 levels rise due to metabolic activity, it causes a corresponding decrease in blood pH, which leads to an increase in respiratory rate to enhance the removal of carbon dioxide from the body.

The central chemoreceptors located in the medulla oblongata are particularly sensitive to changes in Pco2, making it the most significant factor in stimulating adjustments in ventilation. As carbon dioxide levels are closely tied to acid-base balance, the body prioritizes maintaining homeostasis through appropriate adjustments in respiration.

While other factors, such as PO2 and pH levels, do play a role in respiration, they are not as pivotal as Pco2 in the regulation process at rest. Body temperature can influence metabolic rate and subsequently affect ventilation, but it is not a primary regulator of respiration like Pco2 is. Thus, carbon dioxide levels are essential for prompting the necessary respiratory changes to maintain optimal physiological function.