226 ELEMENTS OF PHYSIOLOGY 



401. Gross Anatomy of the Liver. The liver is the largest 

 gland in the body. It is of a reddish brown color and 

 weighs about three and one half pounds. The upper and 

 front surfaces of the liver are very smooth and even. The 

 under surface is very irregular ; it is here that the various 

 vessels with which this active organ is supplied make their 

 entrance or exit. It is located under the right portion of 

 the dome of the diaphragm, and its lower edge reaches a 

 little below the border of the thoracic cage. (Does its left 

 end overlap the stomach? See Plates.) Its connecting 

 vessels, besides the lymphatics, are the hepatic artery from 

 the aorta, bringing pure blood ; the portal vein, bringing the 

 digested food ; the hepatic vein, carrying impure blood to 

 the vena cava ; and the bile duct, carrying the bile to the 

 intestine. The bile duct, on its way from the liver, gives 

 off a side branch to the gall bladder. This is a little dark 

 green bag, in which the bile is stored until it is required for 

 digestion (Plates III and IV). 



402. With each inspiration the liver is pushed downward 

 and compressed by the diaphragm, the blood being forced 

 out toward the heart, and it fills again as soon as the breath- 

 ing muscles relax. This rhythmic compression is of great im- 

 portance in keeping the blood supply to the liver fresh and 

 pure, and preventing congestion in it. By tight clothing 

 the liver is often forced downward, out from the cover of 

 the ribs, and becomes permanently displaced. As a result, 

 other organs, lower in the abdomen and pelvis, are crowded 

 upon each other and also become displaced. The circula- 

 tion in the liver is diminished, and hence its activity is 

 decreased and the complexion loses its freshness. 



403. Circulation through the Liver, or Portal Circulation. 

 The portal vein and its function have been mentioned (Fig. 

 1 78 ). When it enters the liver, it does a very unusual thing ; 

 in fact, it conducts itself as no other vein in the body does, 

 except some of the veins in the kidneys. It subdivides 



