respiratory_tract has definitions from the fields of anatomy,zoology
1
[ noun ] (zoology) the passages through which air enters and leaves the body
2
[ noun ] (anatomy,zoology) the system for taking in oxygen and giving off carbon dioxide; in terrestrial animals this is accomplished by breathing

Used in print

(LeRoy Fothergill, "Biological Warfare", in Peter...)

The natural anatomical and physiological defensive features of the upper respiratory_tract , such_as the turbinates of the nose and the cilia of the trachea and larger bronchi , are capable of impinging out the larger particles to which we are ordinarily exposed in our daily existence .

Certain other properties of small particles , in_addition_to those already mentioned in_connection_with penetration of the respiratory_tract , are noteworthy in defense considerations .

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