RESPIRATORY SYSTEM 



347 



Organs of respiration. In the digestive system food 

 is taken into the alimentary canal and from there is 

 carried to all parts of the body by the blood. In a 

 similar manner, in the respiratory system air is taken 



Esophagus 



Fig. 163. Median section through the head showing the relation of 

 the mouth and nasal cavities to the esophagus. 



into the organs, called the lungs, and from there it is 

 carried by the blood to all parts of the body. 



Air enters the body through the two nostrils. It then 

 passes backward into the throat, from which it enters 

 the wind pipe, or trachea, through a slit-like opening, 

 the glottis. Just above the level of the heart the trachea 



