The conducting part of the respiratory system starts with the external nostrils upto the terminal bronchioles whereas the alveoli and their ducts form the respiratory or exchange part of the respiratory system. The conducting part transports the atmospheric air to the alveoli, clears it from foreign particles, humidifies and also bring the air to body temperature. Exchange part is the site of actual diffusion of O 2 /CO 2 between blood and atmospheric air.

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