Relief Model of Respiratory System

Respiratory system has a dual function, on the one hand, It provides oxygen to blood and make sure the metabolism of human cells， on the other hand, It excretes metabolic waste and carbon dioxide to purify the blood from heart, from the front view of this model, It shows clearly to us the main parts of the respiratory system, include nose, throat, trachea and bronchi in respiratory tract and lungs (airways and alveoli)