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BIOLOGY FOR BEGINNERS 



look at it. It is a large muscular organ, nearly filling the front 

 part of the mouth cavity when the jaws are closed. It has great 

 freedom of motion and performs the following functions: 



FIG. 115. Mouth and Throat. 



The object of this plate is to show the relative position of tue organs of the 

 nose and throat, and especially to indicate the course taken by food in swal- 

 lowing, and air in breathing. 



Note that these routes cross each other, making necessary the adaptation 

 mentioned in the text, to prevent food from entering the trachea when being 

 swallowed. 



Attention is called to the size and thickness of the tongue, which we usually 

 think of as long and thin. Its base pushes back and the epiglottis closes down 

 when the food is passing. 



Note also the large size of the nasal cavity and the projecting lobes which 

 help warm and moisten the air, catch dust, and provide surface for the nerves 

 of smell. 



1. It is the organ of taste a sense which aids in selecting 

 foods and in promoting their digestion. 



2. It aids in chewing, by automatically keeping the food be- 

 tween the teeth. 



3. It is concerned in the process of swallowing, since it rolls 



