Which is a function of the respiratory system?

A. Two deep breaths, then inhale deeply again and force out the air quickly: This technique helps clear mucus by mobilizing it toward the larger airways for expulsion.
B. One deep breath and quickly exhale: This method is less effective in mobilizing secretions compared to multiple preparatory breaths.
C. One breath, hold it for 3 seconds, then forcefully exhale three times with mouth open: Holding the breath promotes mucus loosening, and repeated exhalations help clear secretions. While this technique can be correct in some protocols, it is less common for "forceful" cough instructions and may not be the preferred method.
D. Two breaths and force the air out quickly: Lacks the preparatory deep breath necessary for effective secretion clearance.

A. Oxygen diffuses across the alveolar membrane into the blood: This is the primary function of the respiratory system, ensuring oxygenation of blood.
B. The alveoli have cilia that help remove foreign particles: Cilia are present in the respiratory tract, but not in the alveoli.
C. The diaphragm controls respiration: The diaphragm assists with breathing but does not "control" respiration, which is regulated by the brainstem.
D. The bronchioles contain macrophages that phagocytize inhaled bacteria: Macrophages are found in alveoli, not the bronchioles.