The windpipe leading to the lungs is in front of the other tube. It has at its top a little trap-door. This opens when we breathe and shuts when we swallow, so that the food slips over it safely into the passage behind, which leads to the stomach.
If you try to speak while you have food in your mouth, this little door has to open, and some bit of food may slip in. The windpipe will not pass it to the lungs, but tries to force it back. Then we say the food chokes us. If the windpipe can not succeed in forcing back the food, the person will die.
HOW THE FOOD IS CARRIED THROUGH THE BODY.
But we will suppose that the food of our dinner has gone safely down into the stomach. There the stomach works it over, and mixes in gastric juice, until it is all a gray fluid.
Now it is ready to go into the intestines,—a long, coiled tube which leads out of the stomach,—from which the prepared food is taken into the blood.
The blood carries it to the heart. The heart pumps it out with the blood into the lungs, and then all through the body, to make bone, and muscle, and skin, and hair, and eyes, and brain.
Besides feeding all these parts, this dinner can help to mend any parts that may be broken.
Suppose a boy should break one of the bones of his arm, how could it be mended?
If you should bind together the two parts of a broken stick and leave them a while, do you think they would grow together?
No, indeed!