Food Tube, Part 2

A Handbook of Health
by Woods Hutchinson

(Page 5 of 31)

The Lining Surface of the Stomach. Now let us look more carefully at the lining surface of the stomach, for it is very wonderful. Like all other living surfaces, it consists of tiny, living units, or "body bricks" called cells, packed closely side by side like bricks in a pavement. We speak of the mucous membrane, or lining, of our food tube, as if it were one continuous sheet, like a piece of calico or silk; but we must never forget that it is made up of living ranks of millions of tiny cells standing shoulder to shoulder.

These cells are always actively at work picking out the substances they need, and manufacturing out of them the ferments and acids, or alkalies, needed for acting upon the food in their particular part of the tube, whether it be the mouth, the stomach, or the small intestine.

The Peptic Juice. The cells of the stomach glands manufacture and pour out a slightly sour, or acid, juice containing a ferment called

pepsin. The acid, which is known as hydrochloric acid, and the pepsin together are able to melt down pieces of meat, egg, or curds of milk, and dissolve them into a clear, jelly-like fluid, or thin soup, which can readily be absorbed by the cells lining the intestine.

You can see now why you shouldn't take large doses of soda or other alkalies, just because you feel a little uncomfortable after eating. They will make your stomach less acid and perhaps relieve the discomfort, but they stop or slow down digestion. Neither is it well to swallow large quantities of ice-water, or other very cold drinks, at meal times, or during the process of digestion. As digestion is largely getting the food dissolved in water, the drinking of moderate quantities of water, or other fluids, at meals is not only no hindrance, but rather a help in the process. The danger comes only when the drink is taken so cold as to check digestion, or when it is used to wash down the food in chunks, before it has been properly ground by the teeth.

Digestion in the Stomach. Although usually a single, pear-shaped pouch, the stomach, during digestion, is practically divided into two parts by the shortening, or closing down, of a ring of circular muscle fibres about four inches from the lower end, throwing it into a large, rounded pouch on the left, and a small, cone-shaped one on the right. The gullet, of course, opens into the large left-hand pouch; and here the food is stored as it is swallowed until it has become sufficiently melted and acidified (mixed with acid juice) to be ready to pass on into the smaller pouch. Here more acid juice is poured out into it, and it is churned by the muscles in the walls of the stomach until it is changed to a jelly-like substance.

Digestion in the Small Intestine. The food-pulp now passes on into the

small intestine, where it is acted upon by two other digestive juices - the bile, which comes from the liver, and the pancreatic juice, which is secreted by the pancreas.

The liver and the pancreas are a pair of large glands which have budded out, one on each side of the food tube, about six inches below where the food enters the small intestine from the stomach. The liver weighs nearly three pounds, and the pancreas about a quarter of a pound.

Of these two glands, the pancreas, though the smaller, is far more important in digestion. In fact, it is the most powerful digestive gland in the body. Its juice, the pancreatic juice, can do everything that any other digestive juice can, and do it better. It contains a ferment for turning starch into sugar, which is far more powerful than that of the saliva; also another (trypsin), which will dissolve meat-stuffs nearly twice as fast as the pepsin of the stomach can; and still another, not possessed by either mouth or stomach glands, which will melt fat, so that it can be sucked up by the lining cells of the intestine.

What does this great combination of powers in the pancreas mean? It means that we have now reached the real centre and chief seat of digestion, namely, the small intestine, or upper bowel. This is where the food is really absorbed, taken up into the blood, and distributed to the body. All changes before this have been merely preparatory; all after it are simply a picking up of the pieces that remain.

In general appearance, this division of the food tube is very simple - merely a tube about twenty feet long and an inch in diameter, thrown into coils, so as to pack into small space, and slung up to the backbone by broad loops of a delicate tissue (mesentery). It looks not unlike twenty feet of pink garden hose.

The intestine also is provided with glands that pour out a juice known as the intestinal juice, which, although not very active in digestion, helps to melt down still further some of the sugars, and helps to prevent putrefaction, or decay, of the food from the bacteria which swarm in this part of the tube.

By the time the food has gone a third of the way down the small intestine, a good share of the starches in it have been turned into sugar and absorbed by the blood vessels in its wall; and the meats, milk, eggs, and similar foods have been digested in the same way.

There still remains the bulk of the fats to be disposed of. These fats are attacked by the pancreatic juice and the bile, and made ready for digestion. Like other foods, they are then eaten by the cells of the intestinal wall; but instead of going directly into the blood vessels, as the sugars and other food substances do, they are passed on into another set of little tubes or vessels, called the lymphatics. In these they are carried through the lymph glands of the abdomen into the great lymph duct, which finally pours them into one of the great veins not far from the heart. Tiny, branching lymphatic tubes are found all over the body, picking up what the cells leave of the fluid which has seeped out of the arteries for their use and returning it to the veins through the great lymph duct.

Houghton Mifflin Company
Copyright, 1911, By Woods Hutchinson
All Rights Reserved
Tenth Impression

About the Author

Woods Hutchinson (1862-1930) was an American physician, born at Selby, Yorkshire, England. He graduated from Penn College, Oskaloosa, Iowa, in 1880 and received his medical degree from the University of Michigan four years later. He worked as a professor of anatomy at the State University of Iowa and then became a professor of comparative pathology at the University of Buffalo.