Question: what are the 4 main parts of the respiratory system?
Answer: Nose and Nasal Cavity. The nose and nasal cavity form the main external opening for the respiratory system and are the first section of the body's airway—the respiratory tract through which air moves. ... 
Mouth. ... 
Pharynx. ... 
Larynx. ... 
Trachea. ... 
Bronchi and Bronchioles. ... 
Lungs. ... 
Muscles of Respiration.