The Liver

Organs which are not an integral part of the alimentary tube are vital to digestion and nutrition. Of these, the liver and its satellite gallbladder were anciently associated with vagaries of human temperament, reflected in the words “choleric,” “melancholy,” “bilious,” “jaundiced,” “liverish.” The prefix “chol-” means bile or gall. “Melancholy” literally means “black bile,” undoubtedly the most depressing kind. Happily, medical science has advanced a long way from the time when human dispositions were thought to result from combinations of the four humors - blood, phlegm, black and yellow bile.

The liver, the largest solid organ of the body, weighs about four pounds and occupies the upper part of the abdomen beneath the diaphragm. Most of it lies on the right side. It is divided by a fissure into a large right lobe and a smaller, tapered left lobe, the tip of which overlies the stomach near the esophageal junction. As anyone who has bought liver from a meat market knows, the maroon­colored organ appears to be rubbery and homogeneous. Only under a microscope do vast numbers of minute, polygonal structures called lobules become evident. Each lobule contains hundreds of liver cells, arranged like fine spokes radiating out from a central vein. The lobule is interlaced with minute bile and blood capillaries.

The liver is an incomparable chemical plant. It can modify almost any chemical structure. It is a powerful detoxifying organ, breaking down many kinds of

toxic molecules and making them harmless. It is a blood reservoir and a storage organ for some vitamins and for digested carbohydrate (glycogen) which is released to sustain blood sugar levels. It is a manufacturing site for enzymes, cholesterol, proteins, Vitamin A (from carotene) , blood coagulation factors, and other elements. In some circumstances it can resume its embryonic function of red blood cell production.

And the liver produces bile which assists digestion. Bile is an orange-yellow fluid, bitter as gall (which is another name for it), secreted by liver cells and collected through networks of fine channels into the hepatic duct. This joins with the cystic duct from the gallbladder to form the common bile duct which opens into the duodenum.

Bile is a complex fluid containing bile salts, bile pigments, and other and reused. These salts promote efficient constituents. The pigments, derived from disintegration of red blood cells, give the yellow-brown color of the feces, and are excreted. Bile salts are reabsorbed digestion of fats by detergent action which gives very fine emulsification of fatty materials. This not only assists digestion, but gives, perhaps more importantly, efficient absorption of fat elements by villi of the intestines. Bile aids in alkalinization of the intestines.