If you eat proper food, you help not only your stomach but your liver, too; for it has not so many poisons to get rid of. While you are helping your stomach and your liver, you are helping your heart and your brain, and so on. So what you do to help one helps all.
There are, however, some poisons that the liver cannot get rid of; but these the skin or the kidneys carry away. Have you ever seen kidney beans? The bean is the shape of a kidney. The kidneys are in the middle of your back, packed close to your backbone, on a line with your waist. This is a picture of them. Do you see the little tubes leading down from the kidneys, carrying the waste water and poison down into a kind of bag? The walls of this bag, called the bladder, will stretch, and it will hold about a pint of waste water. From the bladder a tube carries the water down out of the body.
THE KIDNEYS AND THE BLADDER
The large tubes are the artery and the vein that carry blood to and from this part of the body.
You can help your kidney-strainers by emptying your bladder at certain times each day. Some children have to empty the bladder much oftener than others, but most children can form what we call regular habits about it, by trying to do it at the same times each day. If you are quite strong, five times a day is often enough: when you first get up, at recess, at noon, at four o’clock, and at bedtime. Many children do it much oftener than this; but as they grow older and the muscles grow stronger, they slowly outgrow this trouble, if they try to form the right habits.
There are many diseases of the kidneys; for, like the liver, they are sometimes over-worked and do not carry the poisons from the body. You are helping your kidneys when you drink plenty of fresh clean water every day, and also when you play or work hard enough to get into a good perspiration; for, as perspiring carries out some of the poisons, it leaves less for the kidneys to pour out. You ought to get into a good perspiration at least once every day, or better, three or four times, if you wish to keep healthy. The Bible says, “In the sweat of thy brow shalt thou eat bread”; and you must earn health and happiness at the same price.
II. SOME FOES TO FIGHT
You have seen that sitting or sleeping in rooms where the air is bad, or eating the wrong kind of food, or working after you are badly tired, will poison your blood and hinder the proper working of that beautiful machine, your body. These poisons are made inside your body, and you can prevent them by living healthfully and wholesomely. But there are other poisons, which may get into the blood from outside the body; and while it is best for you not to think too much about these, or to worry over dangers that may never come, yet it is well to know just enough about some of them to be able to keep out of their way, as far as possible.
The most dangerous form of poisons from outside the body are those made by the germs of some rather common diseases, which, because you can “catch” them from some one else who has them, are called “catching,” or infectious, or contagious.