150 THE ABDOMEN. 



into lobules, in the center of each of which is a blood- 

 vessel, the intralobular vein, from which a network of 

 capillaries extends to the edge of the lobule, there being 

 a capillary on either side of each row of cells. Between 

 the cells also are the intercellular biliary passages, roots of 

 the bile ducts which exist in the connective tissue between 

 the lobules and which join to form two main ducts, one 

 from the right and the other from the left lobe. By the 

 union of these two ducts the hepatic duct is formed, which, 

 after a course of one or two inches, joins the cystic duct 

 from the gall-bladder to form the ductus communis or 

 common bile duct. 



The liver has a double blood supply, the hepatic artery 

 from the celiac axis bringing nourishment to the connect- 

 ive tissue and the walls of the blood-vessels, while the 

 capillaries between the cells come from the portal vein, 

 which, being formed by the junction of the superior and 

 inferior mesenteric, the splenic and the gastric veins, 

 contains the proteins and carbohydrates absorbed during 

 digestion. After its passage through the liver this blood 

 from the portal vein is collected once more into the 

 hepatic veins, which convey it to the inferior vena cava. 

 During its passage, however, various changes take place, 

 for the liver plays an important part in the metabolic 

 processes of the body. 



The liver has two principal functions, the secreting of 

 bile and the storing up of glycogen. The secretion of 

 bile, which is a very important aid to digestion, is prob- 

 ably a reflex act, the presence of peptones in the portal 

 blood after meals acting as a stimulant to the liver cells. 

 For food at once increases the secretion of bile, which is 

 poured from the cells into the small bile ducts and finally 

 passes into the hepatic duct and so to the gall-bladder, 

 where it is stored until needed. Although the flow from 

 the liver is constant, the .amount secreted reaches its 

 maximum when the food gets down into the small in- 

 testine, that is, four or five hours after eating, there being 

 a lull before that. Apart from the process of secretion, 



