Bile

Bile is a fluid secreted from the blood by the liver. One part of it is destined to serve in the process of digestion; the other to be eliminated from the system. It is coloured yellow in man, and in carnivorous and omnivorous animals; it is green in vegetable feeders. The primary cells of the liver (the hepatic cells) separate the bile from the blood of the portal vein, and discharge it into small ducts, which unite to form larger ones, and eventually the right and left hepatic ducts. The latter unite to form the common hepatic duct, which is soon joined by that of the gall-bladder (the cystic duct). This junction forms the common bile duct, which pierces the second part of the duodenum, and running obliquely in its wall for a short distance, opens on its mucous surface.

Bile is constantly being secreted, more copiously after food; while the duodenum is empty, most of it passes up the cystic duct into the gall-bladder where it is stored. But when the contents of the stomach are carried past the opening of the common bile duct, a copious flow of bile takes place into the duodenum, where it is mixed with the food, in order to aid the further processes of digestion.

The composition of human bile is on the average of

The bile-salts (glycocholate and taurocholate of soda) are the most important constituents. If an animal membrane be wetted with a solution of these salts, it allows fatty substances to filter through it much more readily than if pure water or a solution of an inorganic salt be used; and this property aids in the absorption of fatty foods by the intestine. The bile-salts also assist in the emulsification, and to a certain extent, in the solution of fats. The mucin gives bile its viscid consistency. The other organic constituents include fats and soaps; cholesterin, chemically an alcohol, a crystallisable substance which is usually the chief constituent of biliary calculi or gall-stones (see CALCULUS); and the bile-pigments. The ash contains a considerable proportion of iron, derived, like the bile-pigments, from disintegrated red blood corpuscles (see BLOOD).

Human bile has the specific gravity of about 1026 (water = 1000), is of aropy consistence, with usually a yellowish-brown colour; does not readily mix with water, but sinks therein, and only after repeated agitation becomes diffused through the water, which then assumes a frothy appearance resembling soap-suds. Bile has a bitter taste and a faint musky odour. Besides aiding in the digestion of fats, bile stimulates the various muscular fibres of the intestine, and thus aids both the absorption and the propulsion of its contents; while the mucus it contains acts as a lubricant. It has also an antiseptic action, diminishing the putrefactive changes of the intestinal contents. Should, from any cause, the elements of the bile be in excess in the blood, or should the liver suspend the function of secreting it, not only is digestion imperfectly performed, but the general health suffers from the impure condition of the blood, and the patient is said to be bilious. On the other hand, the bile may be secreted, but its escape interfered with, and then its reabsorption will produce Jaundice (q.v.). See also the articles LIVER and DIGESTION.

BILIOUS ATTACK.—When the functions of the liver are temporarily interfered with, and particularly the secretion of bile diminished, most often in consequence of imprudence in eating or drinking, a bilious attack results. The liver, however, is rarely if ever affected alone, the stomach and intestines being also disordered; in most cases the stomach is probably the first to suffer. There are pain and discomfort in the abdomen, usually headache, and a yellowish discoloration of the skin and whites of the eyes; the tongue is furred and the appetite impaired, and the temper often becomes very irritable. Vomiting and diarrhoea often occur, and are in such a case salutary processes. The administration of a purgative is beneficial; and the food taken, if any, must be small in amount, simple, and readily digestible—e.g. milk with potash water, toast, biscuits, &c. See LIVER.