Touring the Intestinal Chemical Plant

SETTLE back in your easy chair, and come with us on an imaginary tour of one of the most interesting chemical plants in the world. The tour is free and is highly educational. It will not take much of your time​—only about ten to twenty minutes, depending on how fast you can take in the information.

Man has designed many kinds of automatic and semiautomatic chemical plants for processing and refining all kinds of raw materials. But none has ever matched this plant you are about to tour. The simplicity of its design, yet the complexity of the many reactions taking place simultaneously, coupled with its high efficiency, its self-maintenance, and its near-perfect automation are things over which biochemists never cease to marvel.

This unusual chemical plant is located in your own abdomen. It consists of a tube that is close to thirty feet long, and well has it been termed “the tube of life.”

Of course, because of its nature we cannot actually walk into this chemical plant to look around, but if you will look at the diagrams in front of you, we will take you on a visual tour.

As we begin our tour, please take note that the first part of this plant is known as the small intestine. It has a diameter of from one to one and a half inches, and a length of about twenty-three feet. This appears to be true in all adults regardless of their height or weight. Later on we are going to look at the second part of this chemical plant​—the large intestine. It is well named because it has an average diameter twice that of the small intestine. This larger tube is between five and six feet long. And just think of this: the building that houses this entire chemical plant is less than a third of a cubic foot in size! Interestingly, too, the walls of this building are expandable to accommodate gas pressures that may enlarge sections of the plant’s tubes to twice their size​—in diameter, not in length.

Its Components

Now let’s take a look at the ‘pipes’ of this chemical plant. They are not made of metal but of organic, flexible, expandable elements, of flesh and blood, consisting of four coats or layers. The outermost layer is a thin membrane, actually an extension of the peritoneum or inner lining of the abdomen. Next we come to the second coat; and notice how unusual it is. It consists of two layers of fibers, the outer running lengthwise and the inner layer being circular. The fibers running lengthwise exert one kind of pressure on the contents of the tube, while the circular fibers apply another kind of pressure. The two layers are programmed so that their activity is coordinated. There is no confusion or working at cross-purposes, and we are not required to direct the operations. Talk about automation! The Maker of this machine, the Creator, certainly had it first!

The third coat consists of areolar or loosely formed connective tissue that joins the muscle coat with the innermost coat. Most important of all is that innermost fourth coat that we will now examine. It is a mucous membrane that lines the inside of the tube. This lining is especially important in the small intestine. Why? Because here the inside layer is equipped to pour digestive juices into the tube on the one hand, and on the other hand is equipped with the ability to absorb digested food elements into the bloodstream where they feed all the cells of the body.

Its Chemical Activity

But before we continue farther on this tour, a few words about the stomach and its relationship to the small intestine. Many persons labor under a misapprehension as to the role the stomach plays in the digestion of food elements and the absorption of digested nutrients. The stomach only begins to digest proteins and does next to nothing about the carbohydrates (the starches and the sugars) or the fats. Absorption in the stomach appears to be limited to minimal amounts of sugar and alcohol. In fact, some persons have gotten along fairly well with most of their stomach removed. In such instances this marvelous chemical plant automatically accommodates itself to the new circumstances​—the small intestine expands its forepart to pouchlike proportions and so manages to take the place, in effect, of the stomach.

What the stomach does is to prepare the food it receives so that it is suitable for further processing in the intestines. By both chemical and mechanical action it breaks down the food particles until they become something like a grayish medium-thick pea soup called “chyme.”

At regular intervals, and automatically, the stomach squeezes some of this chyme through its lower valve (it also has an upper valve). Now take a look at this lower valve of the stomach; it keeps the chyme in the intestines from backing up into the stomach. Because the quantity of digestive juices added to the food mass in this chemical plant is more or less equal to the nutrients absorbed into the bloodstream, the chyme maintains about the same consistency as it moves throughout the twenty-three feet of the small intestine.

In this chemical plant not only are digestive juices supplied through the innermost coating of the intestine, but digestive juices are also received from two other sources. The liver, by means of a tube, supplies bile for breaking down the fats. And the pancreas, by means of two tubes, supplies basically three kinds of enzymes.a These are for the digestion of proteins, carbohydrates and fats. Certain glands in this chemical plant serve to neutralize the acidity of the chyme received from the stomach. Yes, the job done by the stomach requires an acid medium, while that done in the small intestine requires one that is alkaline.

After the food has been digested it needs to be absorbed. In fact, digestion and absorption go on at the same time without interfering with each other. The absorption is by means of these tiny conical projections that you see in the innermost lining of this tube. They act like suction pumps. By means of them the digested protein and carbohydrate elements go directly into the blood. The digested fat particles, however, first enter the lymph, and from there go into the bloodstream.

By the time the chyme has been fully digested and about all its nutrients have been absorbed, the mass has reached the end of the forepart of this chemical plant, the end of the twenty-three feet. But our tour does not end here, for a valve then opens up, allowing this pea-souplike mass to pass into the first part of the large intestine, known as the cecum, which you can now observe. As the mass moves on through the large intestine, water and various mineral elements are absorbed. There is considerable bacterial activity here. For good health this ‘flora,’ as it is known, is absolutely essential.

The Mechanical Action

For the food mass to be digested and absorbed, and for it to travel from the beginning to the end through this chemical plant, something more than gravity is needed. It requires mechanical action. Here is where the two layers of muscle, previously described, come into play. They produce basically two kinds of action: mixing and propulsion. As soon as some chyme passes from the stomach to the small intestine, rhythmical contractions begin​—automatically. At regular distances from one another circular bands of muscle fibers begin to contract and so divide the chyme into segments. Then these muscles relax and others, halfway between the ones that have just relaxed, contract. In this way half of each previous segment becomes part of a new segment, with the result that constantly new surfaces of the chyme are exposed to the chemical actions and absorptive surfaces of the intestines. These circular muscles keep contracting and relaxing under normal conditions from seven to ten times a minute for about a half an hour at a time, all automatically. Then what?

Then the other set of muscles automatically goes into action. By a slow peristalsis the chyme is moved forward, never backward. After the chyme has been moved forward a certain distance the peristalsis automatically stops and the “rhythmic segmentation,” as it is called by some, resumes. It takes from two to four hours for the chyme to travel the twenty-three-foot length of the first part of this chemical plant. Again, periodically, the valve that guards the entrance to the large intestine opens. Then by means of vigorous peristaltic action, all automatic, of course, the chyme, now with practically no nutrients in it, is pushed into the colon or large intestine.

Now let’s observe what goes on in the colon. From here on, as it is being relieved of excess moisture, further peristaltic action forces the mass through the colon. It first goes upward, then across and then downward in the abdomen until the time for the signal to be sounded that it should be expelled from the body. That signal is set off by the hypothalamus in the brain. It is an amazing system, isn’t it?

Having been on this tour today, you are now in a position to understand better how to care for your own intestinal chemical plant.

When Something Goes Wrong

If such things as ulcers, infections from viruses or parasitic amoebas, and the dreaded disease of cancer can be avoided, rarely does anything go wrong with this marvelous digestive plant during the greater part of one’s life. Provided, of course, that a person eats right, gets proper exercise and sufficient rest, and has control of his emotions.

One of the more common problems many people have is with gas or flatulence. It could be caused by some serious ailment or just due to simple nervousness. But it also could be due to improper eating habits or to indulging in certain foods that are likely to cause gas, such as those of the cabbage family and certain legumes.

Another problem that many persons have, especially those engaged in sedentary occupations, is constipation. Here again, the trouble may be due to poor eating habits, not having a balanced diet, or not drinking sufficient water for this chemical plant to function properly. Eating unrefined foods and plenty of fruits, especially prunes and figs, and leafy vegetables may prove helpful. Then again, for acute cases some may prefer to obtain remedies from the drugstore.

At times something goes wrong with this chemical plant and the result is just the opposite of constipation, namely, diarrhea. This may be due to food poisoning, virus infection or it may be due to injudicious eating habits. A simple time-proven remedy is black tea to which nothing has been added. Another remedy is apple pulp, raw or cooked, to which nothing has been added. Some have found unsweetened grape juice helpful. And there are other remedies.

Since the appendix is part of this chemical plant, there is also the possibility of appendicitis, probably the most frequent serious disease of the intestinal tract. The more moderate and wholesome one’s living habits, the more regular and normal the bowel movements, the less likely it is that the appendix will give trouble.

Showing Appreciation

Biologists have spent much time studying this intestinal chemical plant, especially its forepart, and there are still many things that they do not understand. But from this brief tour we have learned some very interesting things. One thing is certain​—the automation and programming of the various chemical and mechanical actions, working together in perfect coordination, could never have come about by blind chance. This is eloquent testimony that our intestinal chemical plant had a very wise Maker, none other than our Creator, the Almighty God Jehovah. Truly we today, with increased knowledge of our organs, have far more reason than did the ancient psalmist King David to say: “I shall laud you because in a fear-inspiring way I am wonderfully made. Your works are wonderful, as my soul is very well aware.”​—Ps. 139:14; 100:3.

Show appreciation, then, for your intestinal chemical plant. For one thing, do not eat too much. It is better to get up from the table feeling that you could have eaten more than to feel stuffed. When you eat too much you put an extra load on your heart, your liver, your kidneys and other parts of your body as well as this intestinal chemical plant. Eating more than you need may also result in your being overweight, which has its own handicaps.

There is also the psychosomatic factor already alluded to. Do not be in a hurry when eating, and keep in a cheerful frame of mind. Why engage in family quarrels over the dinner table or recount all the trials and disappointments of the day?

Harmful emotions such as worry, anger and fear consume much energy and may cause havoc with the automated processes in your stomach and your intestines. As has well been said, “What’s ‘eating you’ can do more harm than what you are eating.” It is a true proverb that cheerfulness is like a good medicine but low spirits sap a man’s strength.​—Prov. 17:22.

Our Creator, the Maker of the intestinal plant, did a fine job in producing this ‘tube of life’ in which amazing chemical and mechanical functions take place. Show appreciation for it and the rest of your body by wise living habits. Doing so, you will have a minimum of discomfort and trouble and will be the more likely to enjoy good health and years of life. As for us, it has been a pleasure to take you on this tour of the intestinal chemical plant.

[Footnotes]

[Picture on page 16]

LARGE INTESTINE

SMALL INTESTINE

[Picture on page 16]

The four layers of the small intestine

[Picture on page 17]

Chyme from stomach enters small intestine through pyloric valve (enlarged above)

[Picture on page 18]

Absorption is by means of tiny projections