FUNCTIONS OF THE LIVER 



77 



absorbed from the intestines into the portal circulation 

 and carried to the liver which again extracts them from 

 the blood. This is called the circulation of the bile. 



Secretion of Bile. It is believed that there are no 

 special secretory nerve fibers whose stimulation excites 

 the secretion of bile. Apparently the flow is automati- 

 cally regulated by the blood flow, since stimulation of 

 the splancJiic nerves, which carry vasomotor fibers to 

 the liver, increases the flow of bile. Secretin, whose 



Fig. 16. The microscopic structure of the liver. (Highly magnified.) 

 A, Lobule, showing the intralobular plexus; B, Lobule showing the hepatic 

 cells. (Buchanan's Anatomy.) 



action on pancreatic secretion has been related, stimu- 

 lates the flow of bile. As soon as the acid chyme is 

 thrown into the duodenum, not only is the activity of 

 the liver excited, but the gall bladder is stimulated to 

 contract and there is an outflow of ready formed bile 

 into the duodenum. When this is prevented, as by a 

 gallstone plugging the bile duct, or from any cause, bile 

 gets into the blood and the condition of jaundice is 

 produced. 



