,• The major organs of the respiratory system function primarily to provid
oxygen to body tissues for cellular respiration, remove the waste prod
carbon dioxide, and help to maintain acid-base balance.
• Portions of the respiratory system are also used for non-vital functions,
sensing odours, speech production, and for straining, such as during ch
or coughing.
• Functionally, the respiratory system can be divided into a conducting zo
a respiratory zone.
• The conducting zone includes the organs and structures not directly inv
in gas exchange (which takes place in the respiratory zone), with its ma
functions being to provide a route for incoming and outgoing air, remov
debris and pathogens from the incoming air, and warm and humidify th
incoming air.
• Several structures within the conducting zone perform other functions
e.g., the epithelium of the nasal passages is essential to sensing odour
the bronchial epithelium that lines the lungs can metabolize some airbo
carcinogens.
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