276 



THE INTESTINAL JUICE. 



in the faeces. The taurocholic acid, as far as it is not absorbed, is easily decom- 

 posed in the intestine, by the putrefactive processes, into cholalic acid and taurin; 

 the former of these is found in the fasces, but the taurin at least seems not to be 

 constantly present. Part of the cholalic acid is absorbed, and may unite in the 

 liver either with glycin or taurin (Weiss). 



(5) The fseces contain mere traces of lecithin. 



Impaired Nutrition. The greatest part of the most important biliary constituents, the bile- 

 acids, re-enter the blood, and thus is explained why animals with a biliary fistula, where all the 

 bile is removed (without the animal being allowed to lick the bile), rapidly lose weight. This 

 depends partly upon the digestion of the fats being interfered with, and also upon the direct 

 loss of the bile-salts. If such dogs are to maintain their weight, they must eat twice as much 

 food. In such cases, carbohydrates most beneficially replace the fats. If the digestive 

 apparatus is otherwise intact, the animals, on account of their voracity, may even increase in 

 weight, but the flesh and not the fat is increased. 



Bile partly an Excretion. The fact that bile is secreted during the foetal 

 period, whilst none of the other digestive fluids is, proves that it is an excretion. 



The cholalic acid which is reabsorbed by the intestinal walls passes into the body, and seems 

 ultimately to be burned to form CO ? and H0. The glycin (with hippuric acid) forms urea, as 

 the urea is increased after the injection of glycin. The fate of taurin is unknown. When large 

 quantities are introduced into the human stomach, it reappears in the urine as tauro-carbamic 



acid, along with a small quantity of unchanged 

 taurin. When injected subcutaneously into a 

 rabbit, nearly all of it reappears in the urine. 



[Practioal. In practice it is important to re- 

 member that bile, once in the intestine, is liable 

 to be absorbed unless it be carried down the 

 intestine ; hence, it is one thing to give a drug 

 which will excite the secretion of bile, i.e., a 

 hepatic stimulant, and another to have the bile so 

 secreted expelled. It is wise, therefore, to give a 

 drug which will do both, or at least to combine a 

 hepatic stimulant with one which will stimulate 

 the musculature of the intestine as well. Active 

 exercise, whereby the diaphragm is vigorously 

 called into action to compress the liver, will aid in 

 the expulsion of the bile from the liver (Brunton). ] 



183. THE INTESTINAL JUICE. Length of 



Intestine. The human intestine is ten times 

 longer than the length of the body, as measured 

 from the vertex to the anus. It is longer com- 

 paratively than that of the omnivora. Its mini- 

 mum length is 507, its maximum 1194 centimetres 

 [17 to 35 feet] ; its capacity is relatively greater in 

 children (Beneke). 



The succus entericns is the digestive 

 fluid secreted by the numerous glands of the 

 intestinal mucous membrane. The largest 



E 



.Mucous 

 coat. 



B.g 





'4L 



M 



m 



Muscu- 

 laris 

 mucosae. 



Sub- 

 vmucous 

 coat. 



Muscular 

 coat. 



Serous coat. 



Fig. 198. 



Vertical section of duodenum (cat), x 30. 

 E, epithelium ; c and I, circular and longi- 

 tudinal muscular fibres ; L.g, Lieberkiihn's amount is produced by Lieberkuhn's glands, 

 glands; B.g, Brunner's glands, g, ganglion w jjy e j n t ^ e duodenum there is added the 

 cells ; v, villi. scanty secretion of Brunner's glands. 



Brunner's glands are small, branched, tubular glands, lying in the sub-mucosa of the duo- 

 xlenum. Their fine ducts run inwards, pierce the mucous membrane, and open at the bases of the 

 villi (fig. 198). The acini are lined by cylindrical cells, like those lining the pyloric glands. In 

 faet Brunner's glands are structurally and anatomically identical with the pyloric glands of the 

 stomach. During hunger, the cells are turbid and small, while during digestion they are large 

 and clear. The glands receive nerve-fibres from Meissner's plexus (Drasch). 



.... I. The Secretion of Brunner's Glands. The granular contents of the secretory 

 cells of these glands, which occur singly in man, but form a continuous layer in 

 the duodenum of the sheep, besides proteids consist of mucin and a ferment- 

 wbstance..oi unknown constitution. The watery extract of the glands causes (1) 



