THE LIVER 155 



away from the liver a fluid called the bile, which is prepared from 

 the blood. 



The first two convey their contents to the organ, and the last 

 Vffofrom it. 



The portal vein (Lat. vena portce, or vein of the gate the 

 gate being the depression between the lobules of the liver) conveys 

 to the liver a large volume of blood which it collects from the 

 veins of the stomach, intestines, pancreas, and spleen. This blood 

 has already circulated through the capillary systems of these 

 organs, and is therefore of 

 a dark purple colour, and 

 at the same time is very 

 rich in nutritious matter. 



The hepatic artery (Gr. 

 hepar, the liver) brings to 

 the liver a supply of bright 

 arterial blood direct from 

 the descending branch of 

 the aorta. The office of 

 this blood is to nourish the 

 structures of the liver. 



The blood of both these 

 vessels, after it has circu- 

 lated through the capillaries 

 of the liver, is collected by 

 the branches of the hepatic 

 vein, which vessel con- 

 veys it directly into the 

 ascending or inferior vena 

 cava (see fig. 128). 



The hepatic duct con- 

 veys the bile into the gall- 

 bladder or into the duo- 

 denumto the former if 



digestion is not going on, F ^ '^- Vem and lts 



and to the latter if the di- 

 gestive organs are active. 



The branches of the 

 portal vein, the hepatic 

 artery, and the hepatic 

 duct all run together, side by side, in canals which are called 

 portal canals. 



The substance of the liver is made up of small lobules, each 

 about one-twentieth of an inch in diameter, and therefore distinctly 

 visible to the naked eye. Each lobule is formed of a peculiar 



/, liver, under-surface ; gb, gall-bladder ; st, sto- 

 mach ; sj>, spleen ; /, pancreas ; tin, duodenum ; 

 ac, ascending colon ; cd, descending colon ; a, b, 

 c, d, e, the portal vein and its branches. Por- 

 tions of the duodenum and colon have been 

 removed. 



