Respiratory tract

The Respiratory tract is a part of the biological Respiratory system. It's only called this when talking about humans, as all different animals have different Respiratory systems. The Respiratory tract is made of a upper and lower section, including the Nasal cavity, Lungs, Trachea, Primary bronchi, Pharynx and the Larynx.  As you breathe air, the Nasal cavity works as a air filter, trapping dangerous pollutants and other harmful things from the air. Through the Larynx, oxygen will start to move through the trachea into an intersection that moves air to the left and right Primary bronchi. The Primary bronchi then splits it's oxygen into tertiary and secondary bronchi, as it passes through the airway and eventually comes into contact with alveoli and then exchanges Gas functions. The reason food doesn't get stuck in the lower tract is due to the diaphragm passing by a small flap, known as the epiglottis, to block food access into the lungs. The lungs are enclosed in a serous membrane, which folds in on itself to create a 2-layered barrier known as the pleurae, this 2-layered barrier being highly protected by the rib cage.