Where in the respiratory tract is the air filtered, warmed, and moistened?

The Conducting zone of the Respiratory system ( = Air conducting part ).

• where no gas exchange occurs due to thick walls.
• it extends from nose to the end of the terminal bronchioles.
• it includes ( nose - mouth - nasopharynx - larynx - bronchi - non respiratory bronchioles ).
• it performs the following functions : 1- Conduction of air into the respiratory zone. 2- Air conditioning : inspired air reach the respiratory reaches the respiratory zone at a temperature of 37 C.to maintain a constant internal body temperature warming. 3- Humidification of the inspired air : Air is saturated with water vapor to protect delicate lung tissue from desiccation. 4- Filtration and cleaning : - the air conducting part filters air from particles and bacteria. - Mucous secreted by cells of the conducting zone serves to trap small particles in the inspired air and thereby performs a filtration function this mucous is moved along at a rate of 1 to 2 centimeters per minute by cilia projecting from the tops of epithelial cells that line conducting zone. there are 300 cilia per cell that beat in a fashion to move mucus toward the pharynx, where it can either be swallowed or expectorated ( ciliary escalator ). 5- Protective reflexes : as sneezing reflex and cough reflex for removal of foreign bodies and irritant substances from the respiratory passages. 6- Phonation : - the vocal cords ( = 2 strong bands of of elastic tissue ) lie stretched across the lumen of the larynx. - the movement of air across them causes their vibrations which initiate the different sounds of speech.( = voice production ).