The Gastrointestinal System
Parts of the system. The gastrointestinal system might be thought of as a long passage through which food passes. It has glands attached to it that pour chemicals into the passage. These chemicals digest the food as it passes along the passageway. The purpose of this system is to convert the food you eat into substances your cells can use.
The mouth, stomach, intestines, and other parts of the gastrointestinal system digest food by both chemical and muscular action. The glands in the system secrete fluids that break down the foods into usable substances. The muscles in the mouth, esophagus, stomach, and intestines break the food into small particles and keep the food moving through the various stages of chemical digestion.
You will be able to understand all these processes when you read how foods pass through the digestive system. Every food is acted upon by one or more chemicals in the system.
Digestion in the mouth. The first step in digesting food takes place in the mouth, where you chew food. By chewing food, you break it into bits small enough for the digestive juices to work on. The saliva in the mouth is the first digestive juice. It breaks down some of the carbohydrates, or starches, and changes them to a simple sugar.
After food is chewed and mixed with saliva, it is forced down the esophagus by muscular activity called peristalsis. Peristalsis is the progressive contracting of ringlike muscles in the esophagus that forces the food down the canal into the stomach.
Digestion in the stomach. When the food gets to the stomach, it is mixed with hydrochloric acid and agitated by muscular action. The acid makes it possible for several special chemicals, called enzymes, to act on the food. These chemicals break down the protein, curdle milk, and convert fat into a substance the body can use.
In the intestine. When the liquid food passes into the small intestine, it is acted upon by still more enzymes. Actually, most of the digestion takes place in the intestine. In addition to the enzymes secreted by the walls of the small intestine, other secretions act on the liquified food. The food moves along the intestine by peristaltic action, and by the time it reaches the large intestine, or colon, the food value has been taken out of it.
Food enters the blood. As you have learned earlier, the food must enter the blood stream before it can feed the cells of the body. This is accomplished by tiny projections called villi that stick out into the intestines. The liquified foods pass through the thin walls of the villi and into the capillaries and lymph vessels, which are crowded into each projection.
The walls of the intestine are so lined with villi that they resemble the surface of a turkish towel. Once the digested protein and carbohydrates are passed into the blood and lymph, they are transported directly to the cells. These substances feed the cells and keep the body alive.
First Aid for Asphyxiation - Part 1
Accidental asphyxiation. Stoppage of breathing occurs most often in drownings. However, it may occur in carbon monoxide poisoning and other accidents. When a person stops breathing, serious injury and death can follow in a few minutes. Therefore, asphyxiation, or stoppage of breathing, must be given immediate first aid.
The best way to eliminate the danger of asphyxiation by drowning is to follow the water-safety rules you will find in this book. Care of automobile exhaust systems will eliminate the danger of asphyxiation by carbon monoxide poisoning. Proper handling and storage of old refrigerators are other good ways to reduce the danger of accidental asphyxiation.
When breathing has stopped. Always begin artificial respiration immediately upon discovery of an asphyxiated person. Do not believe bystanders who claim that there is no hope, or that the "victim has been out for an hour." The excitement of an accident often wrecks people’s sense of time and judgment. One minute may seem like twenty during the excitement of an accident.
When you begin first aid for stoppage of breathing, you should use the mouth-to-mouth method of rescue breathing. This is the easiest and most effective way to force air into a victim’s lungs. According to the Red Cross, it is the best of the methods of resuscitation, or revival.
Mouth-to-mouth breathing. If you need to administer rescue breathing to a person, proceed with the following steps.
1. Lay the victim on his back. Turn his head to one side and quickly wipe out any foreign matter that is present in his mouth. Check to see that his throat is clear.
2. Kneel beside him and tilt his head as far back as possible so that his chin is pointing up. Pull or push his jaw into a jutting-out position. Hold the jaw in this position while proceeding with the mouth-to-mouth breathing. These procedures will keep the victim’s tongue from obstructing the flow of air into his lungs.
3. Open your mouth wide. Place it over the victim’s mouth so that a leakproof seal is formed. At the same time, close his nostrils. Blow sharply into the victim’s mouth.
4. If you see the victim’s chest rise, proceed. Otherwise, check his tongue and head position. If you still fail to get air to the victim’s lungs, turn him to one side and deliver several sharp slaps to the middle of his back in an attempt to dislodge the obstruction.
5. Once the airway is clear, blow vigorously into his mouth once every five seconds (twelve times a minute). After each time you blow into the victim’s mouth, remove your mouth and listen for the return rush of air. This indicates air exchange. Then repeat the process.
For a young child, blow gently; for a baby, in puffs. Children should receive twenty breaths a minute instead
of the adult twelve.
6. Continue rescue breathing until the patient begins breathing for himself or he has been declared dead by a doctor.
If you do not wish to come into such close contact with a victim, you may wish to spread a handkerchief over his mouth. This will not obstruct the passage of air to any great degree.
You may be able to use an airway. This is a tube made especially for mouth-to-mouth breathing. It is designed to eliminate mouth-to-mouth contact and to keep the victim’s throat clear during rescue breathing. An airway can be obtained at most drug stores.
If you cannot or will not use mouth-to-mouth breathing, you can use another method. Other methods of resuscitation are effective, but none is as easy for the rescuer nor as effective as the mouth-to-mouth method.
Think for Yourself
Why should you not discontinue rescue breathing if a bystander says, "He’s dead now. Nothing will save him"?
