VENTILATION - VENTILATION (How does the inspired air get...

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VENTILATION (How does the inspired air get into the alveoli?) AIRWAYS AND AIRFLOW : Inhaled air passes through the conducting airways and eventually reaches the respiratory epithelium of the lungs. The conducting airways consist of a series of branching tubes which become narrower, shorter and more numerous as they penetrate deeper into the lung. The trachea divides into right and left main bronchi , which in turn divide into lobar , then segmental 12 bronchi . This process continues down to the terminal bronchioles , which are the smallest airways without alveoli. Since the conducting airways have no alveoli they do not take part in gas exchange but constitute the anatomical dead space . Its volume is about 150 ml but it varies because airways are not rigid; during inspiration, respiratory tubes are lengthened and dilated, especially in deep breathing. Since the airways serve as a barrier as well, harmful foreign material including most micro- organisms can not easily enter the lower respiratory passages. The very first barrier starts at the vestibules
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VENTILATION - VENTILATION (How does the inspired air get...

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