76 HUMAN PHYSIOLOGY. 



The Earthy phosphates are insoluble in water but held in solution in the 

 urine by the acid reaction. If the urine becomes alkaline, they are 

 deposited copiously, and yet may not be increased in quantity ; from 1 5 to 

 25 grains are excreted in 24 hours. The sulphates are those of sodium and 

 potassium ; they are very soluble and do not appear as a precipitate ; the 

 average quantity excreted in 24 hours is about 60 grains. 



Abnormal ingredients appear in the urine at times, in pathological con- 

 ditions, e. g., sugar, albumen, biliary salts, etc. 



The Gases of the urine are carbonic acid and nitrogen. 



LIVER. 



The Liver is a highly vascular, conglomerate gland, appended to the 

 alimentary canal, and performs the triple office of (i) excreting bile, (2) 

 elaborating blood and (3) secreting glycogen. 



It is the largest gland in the body, weighing about 4^ pounds; it is 

 situated in the right hypochondriac region, and retained in position by five 

 ligaments, four of which are formed by duplicatures of the peritoneal 

 investment. 



The proper coat of the liver is a thin but firm fibrous membrane, closely 

 adherent to the surface of the organ, which it penetrates at the transverse 

 fissure, and follows the vessels in their ramifications through its substance, 

 constituting Glissorts capsule. 



Structure of the Liver. The liver is made up of a large number of 

 small bodies, the lobules, rounded or ovoid in shape, measuring the -fa of 

 an inch in diameter, separated by a space in which are situated blood 

 vessels, nerves, hepatic ducts and lymphatics*. 



The lobules are composed of cells, which, when examined microscopi- 

 cally, exhibit a rounded or polygonal shape, and measure, on the average, 

 the fl fav of an inch in diameter ; they possess one, and at times two, nuclei ; 

 they also contain globules of fat, pigment matter, and animal starch. The 

 cells constitute the secreting structure of the liver, and are the true hepatic 

 cells. 



The Blood vessels which enter the liver are (l) The portal vein, 

 made up of \he gastric, splenic, superior and inferior mesenteric veins ; (2) 

 the hepatic artery, a branch of the cceliac axis ; both of which are invested 

 by a sheath of areolar tissue; the vessels which leave the liver are the 

 hepatic veins, originating in its interior, collecting the blood distributed by 

 the portal vein and hepatic artery, and conducting it to the ascending vena 



