Respiratory System

A)protecting respiratory surfaces from dehydration, temperature changes, or other environmental variations.

B) defending the respiratory system and other tissues from pathogenic invasion.

C) providing an extensive area for gas exchange between air and circulating blood.

D) moving air to and from the exchange surface.

E) preventing choking from accidental respiration of chewed food.

A) upper respiratory tract.

B) lower respiratory tract.

C) lungs.

D) alveoli.

E) bronchioles.