Your Table of Contents Part 1 – Food Digestion
The food digestion canal is a soft tube with a hard life. Indeed, a long soft tube with, very often, a short, hard life. Its trials and troubles concern us all, for it is the one essential organ wherewith we live on our daily bread. One of our daily duties is to get into that tube sufficient food and drink so that the aggregation of living cells comprising our body will be nourished.
This duty we all try to perform.
With some of us the duty is a pleasure. with others, just a duty. Appetite determines whether it shall be the one or the other. Our appetites, in turn, depend on our state of mind, and this is dependent upon our state of health. To make the circle complete, our health is sustained by our state of nutrition. Verily, a biological merry-go-round.
This long, soft tube starts at the mouth and travels down through the body in a most intimate manner for a distance of some thirty-two feet, proving that though the shortest distance between two points is a straight line, the longest way round is, in this instance, the most nutritious. The manner in which these thirty-two feet of the food digestion canal are accommodated in the rather limited space of our interiors is by an extensive coiling and folding of the tube in the abdomen.
The reason the tube is so long is that much work has to be done on the food before it can be finally absorbed and used. These processes, digestion and assimilation, are varied and require time. To accomplish these tasks, Nature has found it advantageous to lengthen out the tube so that while one portion of the food is being chewed, other portions may be digesting, and still others may be undergoing absorption.
It must be apparent that we cannot use the many foods we eat in the exact form in which they are taken into the mouth. On the contrary, the food must be ground up by our teeth and the various kinds “sorted,” so to speak. Even after we have the meat, bread, and vegetables thoroughly chewed, still further sorting of a chemical nature must take place.
This chemical sorting is known as digestion and is accomplished by various digestive juices that our long soft tube, the food digestion canal, has learned throughout its lifetime to manufacture and pour out into the chewed food that enters it. Indeed, so well have the digestive organs learned this trick that the very taste and sight of food will cause these juices to be secreted. This is the reason we have appetite and the reason our cooks strive to prepare for us foods that look and taste good.
If food tastes good we are inclined to keep it in our mouths longer, to chew it more thoroughly, and to mix it more completely with the saliva, a digestive juice secreted in our mouths. This saliva immediately digests, that is, makes ready for absorption, much of the starchy material in our food. Moreover, thorough chewing not only leads to an abundant secretion of alkaline saliva but mixes it with the food.
When the latter enters the stomach there is immediately stimulated a plentiful secretion of hydrochloric acid, one of the digestive juices of the stomach. We all know from our high school chemistry how an acid neutralizes an alkali, and Mother Nature apparently took the course before we did. Here in the stomach digestion of meat, eggs and other proteins begins. The chemical sorting of the food materials into simpler and chemically smaller substances continues both here and in the small intestines. In the latter, bile and other intestinal digestive juices try to complete the work of digestion so that when the food is passed into the large intestine most of the digestion that will ever occur has already taken place.
I speak of the passing of food through the intestines, and perhaps you wonder what causes the food materials to be continuously passed along the tube toward the lower bowel. The answer is as simple as swallowing. The first swallow really starts the process, and it automatically proceeds down the entire tube. When you swallow, the muscles of the tube, here called the throat. contract. The food can go only in one direction, namely, down, and quite without your knowledge.
