The functions of the system

1: the respiratory system supplies oxygen to the body's cells and removing carbon dioxide from the blood.

2: the respiratory system (tract) cleans, warms and moistens air during the trip to the lungs

3: the lungs (a part of the respiratory system) fills the alveoli and sends oxygen and other gasses through the body, and once the blood extracts the oxygen and releases carbon dioxide to the alveoli than the nitrogen and the rest of the oxygen and carbon dioxide can be released.