82 



ELEMENTARY BIOLOGY 



Fig. 28. The digestive organs in man 



(7, entrance to mouth ; b, the pharynx, — a sort of 

 vestibule with seven passages leading out of it, 

 two to the nostrils, one to the mouth, one to the 

 gullet, one to the windpipe, and one to each ear 

 (the Eustachian tubes, see p. 240) ; <:, the gullet, 

 or esophagus ; ci, the stomach ; e, the pylonis, 

 opening from the stomach to the small intestine ; 

 f, the liver ; g, the gall bladder ; h, duct from the 

 gall bladder and the liver to the small intestine ; 

 i, duct from the pancreas to the small intestine ; 

 /, small intestine ; k, large intestine ; /, vermiform 

 appendix ; m, rectum ; n, the diaphragm, separat- 

 ing the chest cavity from the abdominal cavity ; 

 o, the pancreas. The arrows indicate the course 

 taken by food in passing from the mouth through 



the alimentary canal j^p^ ^^^ yOU Can SCC, shoW- 



ing through the skin, one wave of contraction after another 

 pass along the gullet, from the head to the trunk. 



The thorough mixing of 

 saliva with the food makes 

 it easier for the whole mass 

 to slide along into the 

 throat, and later into the 

 gullet, since the surface 

 of the mass is thus coated 

 with the slippery mucin of 

 the saliva. 



117. Swallowing. After 

 the mouthful of food has 

 been thoroughly chewed, 

 it is pushed back by the 

 tongue and passed into 

 the throat chamber, or 

 pharynx (see Fig. 28, b), 

 from which it passes di- 

 rectly into the gullet, or 

 esophagus. The swallow- 

 ing is not merely a falling 

 down of the food from the 

 pharynx into the stomach. 

 It is an active carrying 

 brought about by the suc- 

 cessive contraction of rings 

 of muscles that lie in a 

 series in the wail of the 

 gullet. If you watch a 

 horse drinking water from 

 a pond or from a pail set 

 on the ground, you can 

 see him swallow the water 



