A 5 year old child announces to her parents that she is going to hold her breath until she is allowed to watch more TV. The parents are not worried. Explain why the parents are not worried. Explain how the child's blood carbon dioxide levels and blood hydrogen ion and bicarbonate ion levels change while she is holding her breath.

Parents are not worried because they know that when the child holds her breath, the level of carbon dioxide will increase and activate breathing centers forcing her to breathe.

A child's blood carbon dioxide levels, blood hydrogen ion, and bicarbonate ion levels all increase during breath-holding increasing pCO2 (partial pressure of carbon dioxide).

PCO2 reflects how much carbon dioxide is dissolved in the blood.