The Physiology Of The Colon

The function of the colon is largely that of a receptacle for unusable and waste matters, a sort of human garbage box. On this account, perhaps, this part of the food tube has been habitually neglected. It has been regarded as of little consequence. But modern studies of this part of the intestine have shown that by neglect this temporary reservoir of wastes may become a veritable breeding place of miseries and maladies almost too numerous to mention. So many and so serious are the disorders of mind and body which are now traceable to this part of the food tube, that not a few eminent surgeons have advocated and practiced the actual removal of the colon in cases of chronic disease of various sorts, and in many instances with surprisingly good results.

Professor Metchnikoff, of the Pasteur Institute, Paris, Dr. Arbuthnot Lane, head surgeon of Guy's Hospital, London, Dr. Barclay Smith, and numerous other scientific men, eminent bacteriologists, physiologists, anatomists and surgeons, have even announced the belief that the colon is a useless and often dangerous structure and that it may be advantageously dispensed with.

The writer does not accept this view, but holds with Professor Keith, the eminent English anatomist, that the evils attributed to the colon are really due to the adoption by man of a dietary unsuited to his anatomy. All vegetable-eating animals have long colons, as has man. The presumption is that a vegetable diet requires a long colon. Meat-eating animals, as the dog, have short colons. The frog while in the tadpole state is a vegetable feeder and has a very long colon. The adult frog feeds upon flesh and has a very short colon.

The Wrong Use To Which We Put The Colon

The trouble with the civilized colon is not that it is too long, but that it is put to a wrong use. Civilized man has adopted the dog's diet while having the colon of the chimpanzee. It may be admitted that if a man is to feed on the diet of the dog he ought to have his colon abbreviated. This is, in fact, the only way in which he could avoid a dangerous biologic misfit.

It is hardly to be supposed, however, that Nature has made so grave an error as to give to man an organ which is not only a useless appendage, but at the same time a prolific source of mischief. It seems more rational to believe that if the colon, an organ useful under normal conditions of life, is found to be so great a source of mischief in our civilized life, it is because of abnormal and pernicious habits or other influences connected with the life of the average civilized man.

The remedy is to be sought then, not in the extirpation of a portion of the body, but in a correction of those habits of life in which there has been a departure from the condition normal to the human species, and a return to practices and conditions which are physiologically and biologically correct for the genus homo.

The First Function Of The Colon

One important function of the colon is to receive and to discharge from the body the unusable residue of foodstuffs. If these foodstuffs are of such a nature that they readily undergo putrefaction, as do meats of all sorts, the colon contents will become highly putrescent, offensive and poisonous, while still in the body. A non-putrefying vegetable diet on the other hand furnishes a residue which cannot putrefy, but ferments, forming harmless acids which aid bowel action. Hence the colon is not out-of-date, as its critics have suggested, but is only made to appear as a misfit by the adoption of a diet which belongs to short-colon animals. This view maintained for many years by all advocates of the biologic diet is so eminently reasonable that it cannot fail to be accorded due recognition since it is now supported by so eminent an authority as the world-famous anatomist, Professor Keith, of England.

Another important function of the alimentary canal, one which is quite distinct from its function as a digestive apparatus, is its excretory function. The intestine is the outlet of the bile, from fifteen to twenty ounces being poured into the upper end of the small intestine every twenty-four hours. The bile is the most poisonous of all the bodily secretions, being, according to Bouchard, six times as poisonous as urine. It is through the bile that the body rids itself of alkaline wastes, some of which are highly poisonous in character.

Another fact of very great importance is that the intestine is itself an excretory organ. Certain poisons are excreted by the stomach, others find their way out of the blood through the walls of the gallbladder and the small intestines.

The colon forms a receptacle for all these waste and excretory substances, together with the unusable or undigested residues of the food. But the collection of these waste matters is only an incidental function of the colon, its really important function being to conduct these waste and unusable matters out of the body.

The food normally enters the first part of the colon, or the cecum, in a nearly fluid state, its composition being ninety per cent water, and only one-tenth solid matter. During the passage of the foodstuffs through the twenty-two feet of small intestine, the digestible starches, fats, and proteins are rendered soluble by the digestive fluids, and are practically completely absorbed. The solid parts left consist almost entirely of indigestible remnants of foods, waste products excreted by the liver and the intestinal mucous membrane and microbes which are produced in great numbers in the lower part of the small intestine as well as in the colon. The small intestine is not only the seat of the principal digestive processes, but is also the principal organ of absorption of the digested foodstuffs. The colon normally absorbs only about one-sixth of the water which remains in the material received from the small intestine, the amount of which is estimated at about half a pint, and practically none of the foodstuffs. The small intestine absorbs daily five or six quarts of liquids and all the products of digestion. It is, in fact, the one great avenue for the intake of nutrients, both solid and liquid.

Half of Colon Removed.

Half of Colon Removed.

Diagram of Short Circuiting Operation.

Diagram of "Short-Circuiting" Operation.

About four hours after a meal, bubbling and squirting sounds may be distinctly heard when the ear is placed over the right lower abdomen, and an hour or two later it is easy to produce splashing and gurgling sounds by intermittent pressure over the colon low down in the right side of the abdomen, showing that a considerable amount of fluid has passed from the small intestine, into the cecum. It should be remembered that this is not a mere mechanical process. The fluid food does not pass by gravity from the small bowel into the large intestine as water might trickle from a pipe into a reservoir. The opening of the small intestine into the colon is controlled by a sphincter, the ileocecal valve. This circular muscle holds the food in check in the lower part of the small intestine long enough to make sure that digestion is complete and the absorption of digested foodstuffs practically finished. In other words, the ileocecal valve is a sort of second pylorus, and serves much the same purpose.

The pylorus and ileocecal gates hold back solid and imperfectly digested foodstuffs, permitting the fluid portion to pass on. In the cecum and ascending colon the food is detained by a special process, so that its fluid portion may be absorbed, thus increasing the Consistency of the bowel contents. Gradually a portion of the water is taken up by the absorbents, which are very numerous in this part of the colon, and at the same time the more solid portions are pushed along toward the upper end of the ascending colon, the fluid part dropping back into the cecal pouch for absorption.

Keith, the eminent English anatomist, has recently pointed out new facts of great interest in relation to the control of the movements of the alimentary canal. Keith has shown that the muscular structures of the intestine have the same property of rhythmic action as is possessed by the muscle fibres of the heart. This tendency to rhythmic movement of the individual fibres is an organized, orderly action of certain centers or nodes which are designated as pace makers. These nodes have been shown to exist at the following points along the alimentary canal - the upper or cardiac orifice of the stomach, the pylorus, the duodenum, the ileocecal valve, the transverse colon, the junction of the pelvic colon, the rectum and the internal anal sphincter.

Short Circuit with Colon Removed.

Short-Circuit with Colon Removed.

Short Circuit with Half of Colon Removed.

Short-Circuit with Half of Colon Removed.