Two Nervous Systems One Food Digestion Canal

Your Table of Contents Part 4 -  Two Nervous Systems One Food Digestion System

We now come to that part of the tube where evidence of constipation first assumes form. In the large bowel practically no digestion occurs, and normally most of the absorption of foodstuffs has already occurred in the small intestine. I say normally because there are many people, particularly the victims of nervous stomach problems, in whom this normal process has been disturbed.

In these people the small intestine is apt to be overactive and move its contents on at a speed greater than normal. This renders the digestion of the contained food imperfect and makes its complete absorption impossible. The same thing occurs in people who, for one reason or another, have lost control of the muscular sphincter which acts as a valve between the small intestine and the large intestine.

In still other instances a reason for the imperfect digestion and incomplete absorption may be found in the fact that in order to digest and absorb food substances they must be in solution. Here the wisdom of drinking sufficient water becomes apparent, because without water much of the food that the upper part of the digestive tract has labored so hard to prepare will remain unabsorbed. What also normally remains unabsorbed is that portion of the food, such as fibers of celery, skins of fruit, and gristle of meat, which has defied digestion.

In addition to these, there is a certain amount of digestive secretion, such as bile, which can no longer be used and hence mixes with the unabsorbed products.

This mass of unabsorbed material comprises what is popularly known as the “bowel movement.” At least, it should constitute the bowel movement, but until a movement (that is, its expulsion) occurs, it involves the question: to be or not to be, constipated.

Under ordinary circumstances, the functioning of the food digestion canal proceeds without the help of the conscious brain. It is actuated by an intelligence residing in certain special nerve centers out of the zone of normal consciousness.

At the level of the throat, control is exerted over the muscles of the food digestion canal, as in swallowing, and can be exerted at will. Below this point, however, no direct control is possible until the very terminal portion of the rectum is reached. In the very long stretch between these two points, over thirty feet, that tube known as the food digestion canal depends for its guidance upon an intelligence more or less its own. This guidance is exerted through a very special internal nervous system which serves the internal organs in much the same way as the external nervous system, or voluntary system, acts for the surface of the body to perceive sounds, odors, and contacts.

Because of information we receive through the external nervous system, we adjust ourselves to our surroundings by moving our muscles voluntarily. Thus we go about in the world at large, guided by information received from this external nervous system. The actual moving is done by means of muscles under our control.

However, the internal organs are more definitely concerned with their own world, that world which faces the inside of the food digestion canal. And it has handled the activities of this world for so many generations, and so successfully by itself, that it no longer is under our control. Instead it is managed by a special “Board of Governors,” of which the solar plexus is an important member. Its decisions are executed by the nerve branches of the great sympathetic and parasympathetic systems.

The control of both the muscles of the organs and the glands of secretion must, of course, be capable of regulation in two directions; that is, they must be able to stimulate or they must be able to slow down. And to accomplish this very great task Nature has utilized the same principle that you do when you lift a window. You know, of course, that you can do this with the fingers of one hand even though the weight of the window is in itself considerable. But the builder has cleverly counterbalanced the weight of the window with a sash weight, and thus all you have to do in order to raise the window to any desired position is to get it started.

So, too, the internal nervous system has found that by balancing one set of nerves against another it can achieve great economy of effect and efficiency of action. Thus the sympathetic and parasympathetic nerves bear a plus-and-minus relation to each other, the one stimulating the functions that the other represses. They are both necessary, or at least desirable, in the government of the actions and secretions of the food digestion canal.

What is most essential, however, is that the delicate balance between these two nervous systems must be maintained within normal range of variation. When it is distorted, very naturally, the function of the organs to which it acts as a guide is correspondingly disturbed. Just exactly how a disturbance of this delicate balance may occur is evident upon consideration of what constitutes the environment of the food digestion canal, that is, from what sources disturbing stimuli may come. The answer is that the entire inner surface of the food digestion canal and its channels of communication with the external nervous system represent that environment, or its world.

In other words, any disturbance occurring on the inner surface of the food digestion canal because of irritation by cathartics, food poisons, or bacterial poisons, will tend to disturb this normal balance between the two portions of the internal nervous system. But please note that the balance may also be disturbed through the channels of communication with the external nervous system. Thus we can readily understand how any storm in the outer ocean, represented by the brain and external nervous system, is sure to disturb, in some degree, the ordinarily still waters in the bay itself, the nerve area supplying the internal organs.

Patients and doctors too will fare better in understanding and managing the food digestion canal on the rampage if they bear in mind that it is a tube, a continuous tube, the parts of which are separated from each other by nothing more tangible than a Latin name, a purely theoretical boundary. Recognizing this principle of continuity will do much to help us understand how something poured in one end is bound to influence the other end and everything in between.

The effect referred to is due not only to the actual passage of the food mass but also the intricate and intimate nerve connections which cover the food digestion canal from one end to the other. The news of a wreck on a railroad is telegraphed both up and down the line, and in a similar manner any considerable disturbance gives rise to the reflex messages along the entire food digestion canal.

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