6.4.2 Explain the need for a ventilation system

Ventilation is needed to take in fresh air into the lungs, remove carbon dioxide from the body, which is a product of cell respiration, and to maintain concentration of oxygen and carbon dioxide inside the body. Also, the body needs oxygen to make ATP through cell respiration.

(http://www.normalbreathing.com/images-new/O2-normal.bmp)