25 



The functional processes of digestion are prehension (the taking 

 up of the food by the lips), mastication (chewing or grinding), 

 and, simultaneously with this, insalivation, or mixing the food 

 with saliva, which is secreted by the salivary glands, situated in 

 different parts of the head; deglutition, or swallowing the pre- 

 pared food by means of the tongue, pharynx, and esophagus 

 <gullet). 



Chylification, or the conversion of chyme into chyle, is a 

 change which takes place in the duodenum by the action of the 

 bile and pancreatic fluid, followed by the absorption of the nu- 

 tritive material into the circulation, and finally, defecation, or 

 excretion of the residual, inert matter. 



The ahmentary canal is a musoulo-membranous tube, extend- 

 ing from the lips to the anus. Its walls are composed of mus- 

 cular tissue and lined throughout by mucous membrane. It 

 consists of a continuous series of tubes and cavities, the chief of 

 which are the mouth, pharynx, esophagus, stomach, and intes- 

 tines, where the food passes through various changes and is 

 deprived of its nutritive properties, and the egestive or expulsive 

 portions, by which the residue is expelled from the system. 



The portion of the food which is not absorbed is called effete 

 material (dung) and is expelled through the anus. 



URINARY SYSTEM. 



The organs of this system secrete the urine from the blood and 

 excrete or expel it from the body. These organs are chiefly the 

 kidneys, ureters, bladder, and urethra. The urine, which is a 

 watery fluid, is secreted by the kidneys and carried off by their 

 ducts, the ureters, to a special reservoir, the bladder, where it 

 accumulates and from which it is finally expelled at intervals 

 through the urethra. The kidneys are two in number, right 

 and left, situated on eifher side of the spine, immediately below 

 the lumbar vertebrse. 



The bladder is a musculo-membranous organ and serves as the 

 reservoir for the urine and is situated vnthin the pelvic cavity. 



The urethra is a long narrow tube extending frona the bladder 

 to the head of the penis. 



The normal amount of urine, which is expelled from the blad- 

 der through the penis, secreted in twenty-four hours varies from 

 3 to 6 quarts. The color in health is of a yellowish cast. 



