392 USES OF THE LIVER DUCTLESS GLANDS. 



CHAPTER XIII. 



USES OF THE LIVER-DUCTLESS GLANDS. 



Physiological anatomy of the liver Distribution of the portal vein, the hepatic artery and the hepatic duct- 

 Structure of a lobule of the liver Arrangement of the bile-ducts in the lobules Anatomy of the excre- 

 tory biliary passages Nerves and lymphatics of the liver Mechanism of the secretion and discharge of 

 bile Quantity of bile Uses of the bile Properties and composition of the bile Biliary salts Choles- 

 terine Tests for bile Excretory action of the liver Formation of glycogen in the liver Change of 

 glycogen into sugar Conditions which influence the quantity of sugar in the blood Summary of the 

 glycogenic action of the liver Probable office of the ductless glands Physiological anatomy of the 

 spleen Suprarenal capsules Addison's disease Thyroid gland Myxoedema Thymus Pituitary body 

 and pineal gland. 



PHYSIOLOGICAL ANATOMY OF THE LIVER. 



THE liver has several uses in the economy, which are more or less dis- 

 tinct from each other. It secretes bile, a fluid concerned in digestion and 

 containing at least one excrementitious product. Another office is the for- 

 mation of glycogen, in which it acts as a ductless gland. 



It is unnecessary, in this connection, to dwell upon the ordinary descrip- 

 tive anatomy of the liver. It is sufficient to state that it is situated just be- 

 low the diaphragm, in the right hypochondriac region, and is the largest 

 gland in the body, weighing, when moderately filled with blood, about four 

 and a half pounds (2 kilos.). Its weight is somewhat variable, but in a per- 

 son of ordinary adipose development, its proportion to the weight of the body 

 is about as one to thirty-two. In early life the liver is relatively larger, its 

 proportion to the weight of the body, in the new-born child, being as one to 

 eighteen or twenty (Sappey). 



The liver is covered externally by peritoneum, folds or duplicatures of 

 this membrane being formed as it passes from the surface of the liver to the 

 adjacent parts. These constitute four of the so-called ligaments that hold 

 the liver in place. The proper coat is a thin but dense and resisting fibrous 

 membrane, adherent to the substance of the organ, but detached without 

 much difficulty, and very closely united to the peritoneum. This membrane 

 is of variable thickness at different parts of the liver, being especially thin 

 in the groove for the vena cava. At the transverse fissure, it surrounds the 

 duct, blood-vessels and nerves, and it penetrates the substance of the organ 

 in the form of a vagina, or sheath, investing the vessels, and branching with 

 them. This membrane, as it ramifies in the substance of the liver, is called 

 the capsule of Glisson. It will be more fully described in connection with 

 the arrangement and distribution of the hepatic vessels. 



The substance of the liver is made up of lobules, of an irregularly ovoid 

 or rounded form, and about -g-% of an inch (1 mm.) in diameter. The space 

 which separates these lobules is about one-quarter of the diameter of the 

 lobule and is occupied by the blood-vessels, nerves and ramifications of the 

 hepatic duct. In certain animals, the pig and the polar bear, the division of 

 the hepatic substance can be readily made out with the naked eye ; but in 

 man and in most of the mammalia, the lobules are not so distinct, although 

 their arrangement is essentially the same. The lobules are intimately con- 



