During stimulation of breathing why does carbon dioxide level increase and oxyge!

During stimulation of breathing why does carbon dioxide level increase and oxygen level decrease?

I'm not sure that I understand your question, exactly, but here is my answer to what I think you are asking!!

Carbon Dioxide (CO2) is a by-product of our respiration.
Air that we breath in is rich in oxygen, low in CO2. The oxygen goes in the blood to the cells. The cells use the oxygen to burn glucose, producing CO2 as one of the byproducts. The CO2 returns in the blood back to the lungs.
Air that we breath out is low in oxygen, rich in CO2.

Sensory cells in the aorta respond to the CO2 level in the blood as it leaves the heart and send a stimulus to our nerves to breathe.

So, our urge to breath is driven primarily by our need to get rid of CO2, not the need to get oxygen.

Some people with chronic lung diseases have unusually high levels of CO2 in their blood. Their CO2 sensors become dulled, and a back-up system of oxygen sensors takes over. They are breathing on a oxygen-drive. For these people, administering too-high concentrations of oxygen can actully cause them to stop breathing.

I hope some of this information is what you are looking for.

MM