Respiratory Functions

The respiratory system is much more than a gas-exchange organ. Its first and most obvious job is to exchange oxygen (O2) and carbon dioxide (CO2) between the atmosphere and the blood, so that oxygen reaches every tissue and CO2, a waste product of cellular respiration, is carried away before it builds up to harmful levels.

Beyond this, the respiratory system helps maintain the acid-base balance (pH) of the body. Because dissolved CO2 forms carbonic acid in blood, the rate and depth of breathing can be adjusted moment to moment to keep blood pH within a narrow, safe range - breathing faster blows off CO2 and raises pH, while breathing more slowly conserves CO2 and lowers pH. …