Bile

Bile, the secretion formed by the liver, and discharged into the duodenum through the common bile duct. Human bile is a yellow viscid fluid, bitter in taste, possessing no appreciable odour, of specific gravity 1020 to 1025 (distilled water being 1000). It accumulates during the intervals of digestion in the gall bladder, from which, as the stomach passes on its contents into the duodenum, it is gradually discharged. Its composition is as follows: -

In 1,000 parts of bile there are - Of water about 859 parts Bile salts about 91 parts Fat about 9 parts Cholesterin about 3 parts Mucus and pigment about 30 parts Mineral salts about 8 parts

The Bile salts are the glycocholate and taurocholate of sodium. Their main function is the promotion of the absorption of fatty substances from the intestinal tract. The test for the presence of bile salts is known as Pettenkofer's (q.v.).

Cholesterin possesses a theoretical interest as being the only alcohol found in the body; its practical importance arises from the fact that it sometimes forms the concretions known as gall stones.

The yellow colour of bile is chiefly due to the pigment Bilirubin. In the green bile of the herbivora an oxydised form of Bilirubin called Biliverdin is present. The bile pigment is intimately related to Haemoglobin, the pigment of the blood. The retention of bile pigment causes jaundice (q.v.). The test for bile pigment is known as Gmelin's (q.v.). The functions of the bile are: (i) As an excrementitious substance, it separates excess of carbon and hydrogen from the blood, (ii) To promote the absorption of the fatty elements of the food, (iii) It is a natural purgative, and to its action in hastening the progress of the contents of the alimentary canal is probably to be attributed the antiseptic action bile is said to possess, inasmuch as the prolonged stay in the intestines of material in process of digestion would favour putrefaction.