The respiratory system controls the exchange of gasses between the body and the atmosphere.
Respiratory tract offers the passage for movement of oxygen to enter the blood while carbon dioxide moves out of the blood.
Respiratory tract blocks the entry of dust particles that can damage the system due to the presence of ciliated epithelial cells and removes it through sneezing.
Respiratory tract also helps with the sensation of smell through the nasal tract.
The air moving through the respiratory tract causes vibration in the vocal chord helping with the speech of the person.