Читать книгу How to live: A manual of hygiene for use in the schools of the Philippine islands онлайн

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The third box, which we call the abdominal cavity, is separated from the chest by a broad, thin muscle, the diaphragm. The abdomen has a hard floor of bone, but the walls are soft, being made up only of the muscles and the lower ribs. In the abdomen are the stomach and intestines, the liver, kidneys, and other organs of which we shall learn later.

Food is carried from the mouth to the stomach by the muscular tube which passes through the chest just back of the breastbone. This tube is called the esophagus. With the mouth, the stomach, and the bowels, it forms what is called the food canal.

As soon as the food enters the mouth, it begins to turn from solid into liquid form, so that the blood can take it up. We chew the food, so that it may become mixed with the saliva in the mouth; then it is swallowed and goes into the stomach. This is a kind of sack which holds about a quart. Just as saliva is secreted in the mouth and acts upon the food, so in the stomach there is a fluid called the gastric juice, which aids digestion. The gastric juice mixes with the food, dissolves it, and makes it soft, so that it can pass through the lower opening of the stomach into the intestines. Here there are other juices which dissolve still more of the food, until at last it is all liquid and looks like milk.