Respiratory System Write the BLACK Read the RED WHAT DO YOU KNOW ABOUT THE RESPIRATORY SYSTEM? Follow along on pg. 99 of workbook Functions of the Respiratory System bring O 2 (oxygen) into the body and excretes CO 2 (carbon dioxide) a by-product of cellular respiration Cells cant burn nutrients for E without oxygen (O 2 ) (like a candle under a cup) Cellular Respiration =in mitochondria Nutrients + oxygen E + carbon dioxide + water The air we breathe The air we inhale is :The air we exhale is: Nitrogen (N) 78%Nitrogen78% Oxygen (O2)21%Oxygen16% Carbon Dioxide 0.04%Carbon Dioxide5% Other gases< 1%Other