Respiratory system
Respiratory system refers to the body of breathing gas into the body and the gas exchange system. In humans and other mammals, the respiratory system includes the respiratory tract, lung and respiratory muscles. Oxygen and carbon dioxide in the respiratory system through the diffusion of the external environment and the blood in the passive exchange, the gas exchange process occurred in the lung cavity. Other animals such as insects have a very simple respiratory function, and for amphibians, their skin is even vital to gas exchange. Plants also have respiratory systems, but the direction of gas exchange can be opposite to the direction of gas exchange in animals, and the stomatal structure on the back of plant leaves is also part of its respiratory system. ...