268 HAND-BOOK OF PHYSIOLOGY. 



THE LIVEE. 



The Liver, the largest gland in the body, situated in the abdomen, 

 chiefly on the right side, is an extremely vascular organ, and receives its 

 supply of blood from two distinct vessels, the portal vein and hepatic ar- 

 tery, while the blood is returned from it into the vena cava inferior by 

 the hepatic veins. Its secretion, the bile, is conveyed from it by the 

 hepatic duct, either directly into the intestine, or, when digestion is not 

 going on, into the cystic duct, and thence into the gall-bladder, where it 



FIG. 196. The under surface of the liver. G. B., gall-bladder; H. D., common bile-duct; H. A., 

 hepatic artery; v. p., portal vein; L, Q., lobulus quadratus; L. s., lobulus spigelii; L. c., lobulus cau- 

 datus; D.-V., ductus venosus; u. v., umbilical vein. (Noble Smith.) 



accumulates until required. The portal vein, hepatic artery, and hepatic 

 duct branch together throughout the liver, while the hepatic veins and 

 their tributaries run by themselves. 



On the outside the liver has an incomplete covering of peritoneum, 

 and beneath this is a very fine coat of areolar tissue, continuous over the 

 whole surface of the organ. It is thickest where the peritoneum is absent, 

 and is continuous on the general surface of the liver with the fine and, 

 in the human subject, almost imperceptible, areolar tissue investing the 

 lobules. At the transverse fissure it is merged in the areolar investment 

 called Glisson's capsule, which, surrounding the portal vein, hepatic ar- 

 tery, and hepatic duct, as they enter at this part, accompanies them in 

 their branchings through the substance of the liver. 



Structure. The liver is made up of small roundish or oval portions 

 called lobules, each of which is about -fa of an inch in diameter, and com- 

 posed of the minute branches of the portal vein, hepatic artery, hepatic 

 duct, and hepatic vein; while the interstices of these vessels are filled 

 by the liver cells. The hepatic cells (Fig. 197), which form the glandular 

 or secreting part of the liver, are of a spheroidal form, somewhat polyg- 



