Final answer:
The involuntary, rhythmic activities that deliver and remove respiratory gases are regulated in the brainstem.
Step-by-step explanation:
The involuntary, rhythmic activities that deliver and remove respiratory gases are regulated in the brainstem. The brainstem contains the respiratory centers that control breathing, specifically the medulla oblongata and the pons. These centers monitor the level of carbon dioxide in the blood and adjust the rate of breathing to keep it within a narrow range. For example, if the carbon dioxide levels increase, the brainstem will signal the diaphragm and intercostal muscles to contract more frequently, resulting in faster breathing to eliminate the excess carbon dioxide.