THE FOOD AND DIGESTION 



325 



from above downwards, force the food down the gullet towards 

 the stomach. 



The (Esophagus (Oe.) is a muscular walled tube lined by a 

 stratified squamous epithelium. 

 The muscles, below the lowest 

 constrictor of the pharynx, are 

 of the visceral type, and are 

 arranged in two layers, an 

 outer longitudinal layer, and 

 an inner circular layer. 



The Stomach is a dilatation 

 of the alimentary canal into 

 which the gullet opens. To 

 the left it expands into a sac- 

 like cardiac end (C.), and to 

 the right it narrows, forming 

 the pyloric end (Py.). Like 

 the gullet, it is surrounded 

 by visceral muscular fibres, 

 arranged essentially in two 

 sets. At the cardiac orifice, 

 the circular fibres form a not 

 very marked cardiac sphincter, 

 and at the pyloric end they 

 form a very thick and strong 

 pyloric sphincter. 



The mucous membrane, 



Which is Covered by a Colum- FIG 144 -Diagram of the Parts of 



/ the Alimentary Canal, from Mouth 



nar epithelium, is largely com- 

 posed of tubular glands, those 

 at the cardiac end containing 

 two kinds of cells, the peptic 

 and the oxyntic cells, those 

 at the pyloric end containing 

 peptic cells alone. 



The Small Intestine is a tube of about 7 metres in length. 

 It has a double muscular coat like the stomach. The mucous 

 membrane, which is covered by a columnar epithelium, is 

 thickly set with simple test-tube like glands Lieberkuhn's 

 follicles and is projected into the lumen of the tube, as a 



to Anus. T., Tonsils; Ph., 

 Pharynx; S.C., Salivary Glands; 

 Oe., (Esophagus; C., Cardiac; 

 Py-, Pyloric Portion of Stomach ; 

 D. , Duodenum ; Li. , Liver ; P. , 

 Pancreas ; J. , Jejunum; /., Ileum ; 

 V., Vermiform Appendix; Col., 

 Colon ; It., Rectum. 



