Final answer:
In a healthy person, respiration is primarily controlled by the level of carbon dioxide in the blood. Cells in the brain monitor and adjust the rate of breathing to maintain a normal range of carbon dioxide, oxygen, and pH levels.
Step-by-step explanation:
In a healthy person, respiration is primarily controlled by the level of carbon dioxide in the blood.
Cells in the brain monitor the level of carbon dioxide and adjust the rate of breathing through the autonomic nervous system, speeding up or slowing down breathing as needed to maintain a normal range.
This ensures that the levels of carbon dioxide, oxygen, and pH are maintained within the necessary limits for the body's functioning.