=117. What becomes of alcohol in the body.=--When alcohol is taken up by the blood, it is carried to the liver. The liver tries to get rid of it by taking some air from the blood and burning it up, just as it burns the real food of the body. But this takes some air from the cells of the body. Then they do not burn as they should.

When a stove gets too little air through its draft, it makes an unpleasant smoke, and cools off. Just so, when the cells of the body do not burn as they should, they produce the wrong kind of smoke and ashes. This poisons the body and makes men sick. The most of the poisoning of alcohol is due to these new poisons.

When alcohol takes air from the cells of the body, they do not get enough air. Then they are like a short-winded boy, and do not do their work well. In this way alcohol makes the body weak.

Alcohol does not cease to be harmful because it is burned up in the body. It is harmful just because it burns so quickly. Using alcohol in the body is like trying to burn kerosene in a coal stove. The body is not made to burn alcohol any more than a coal stove is made to burn kerosene. You can burn a little kerosene in a coal stove if you are very careful. Just so, men can burn alcohol in their bodies. But kerosene will always smoke and clog up the stove, and may explode and kill some one. So alcohol in the body burns quickly and forms poisons.

It always harms the body and may destroy life at once.

=118. Alcohol and the lungs.=--If you run a long race, your lungs will need a great deal of air. If you take strong drink, the alcohol will use up much of the air, and you will not have enough to use on your run. So you will feel short of breath, and will surely lose the race.

You cannot drink and be long-winded.

Two drinks of whisky will use up as much air as the body uses in an hour. It would be easy to smother a person with strong drink. Drunken persons are really smothered; they often die because of the failure of their breathing, even while their heart is able to beat well.

Alcohol often causes the lungs to become thickened. Then air cannot easily pa.s.s through their sides, and a person suffers from shortness of breath. Sometimes these persons cannot lie down at all, but must sit up to catch their breath.

=119. Drinking and taking cold.=--A strong, healthy man can stand a great deal of cold and wet. If he breathes deeply in his work, all the cells of his body get plenty of air, and if he eats good food, the cells get plenty to eat. Then it will take a great deal to harm them.

But alcohol hinders the digestion of their food, and also takes away their air. So the cells are both starved and smothered, and are easily hurt. Then a little cold and wet may do great harm to his body, for a drinker cannot stand bad weather or hard work so well as he could if he should leave drink alone.

Men often drink to keep themselves from taking cold. The alcohol really makes them more liable to take cold. It causes the blood to flow near the surface of the skin; there it is easily cooled, and the drinker soon becomes chilled; then he feels colder than ever. The cold harms the cells of his body, and then the white blood cells cannot easily fight disease germs. For this reason a drinker easily takes cold and other diseases.

=120. Alcohol lessens the warmth of the body.=--Alcohol causes the blood tubes in the skin to become larger. Then more blood will touch the cool air, and the body will become cooler. But because more warm blood flows through the skin, a man feels warmer. But he is really colder. Alcohol makes men less able to stand the cold. Travelers in cold lands know this and do not use it.

=121. How tobacco affects breathing.=--We would not live in a room with a smoking stove. But tobacco smoke is more harmful than smoke from a stove, for it has nicotine in it. Tobacco smoke in a room may make a child sick.

Cigarette smoking is very harmful to the lungs, for the smoke is drawn deeply into them, and more of the poison is likely to stay in the body. The smoke of tobacco burns the throat and causes a cough. This harms the voice.

WHAT WE HAVE LEARNED

1. Air is always being breathed into little sacs inside the body.

The sacs form the lungs.

2. The red blood cells pa.s.s through the lungs, and take little loads of air. They then carry the air through the arteries to the capillaries.

3. In the capillaries the air leaves the red blood cells, and goes to the cells of the body.

4. The air unites with the cells, and slowly burns them to smoke and ashes.

5. The smoke goes back to the blood, and is carried to the lungs and given off by the breath. The ashes go back to the blood and pa.s.s off through the skin and the kidneys.

6. The burning in the cells makes heat.

7. Some of the heat is changed to power, as it is in a steam engine.

8. The heat also warms the body. It keeps it at the same warmth on a cold day as on a hot day.

9. We wear clothes to keep the heat in, and so to keep us warm.

10. The air of a room needs to be changed often. It is made stuffy by our breath.

11. The voice is made by the breath in a box in the neck.

12. Alcohol uses air belonging to the cells of the body.

13. Tobacco smoke has the same poisons as tobacco. It can poison the whole body through the lungs.

CHAPTER XI

THE SKIN AND KIDNEYS

=122. Waste matters.=--The food is burned in the cells. As this burning goes on, the _smoke_ goes off by the lungs and the unburned substances, the _ashes_, go off by the skin and kidneys. The ashes are mostly the minerals of the cells, but there are also some from the burned alb.u.min. All these go back to the blood and are carried to the skin and kidneys.

[Ill.u.s.tration: =The skin (100).=

_a_, _b_ and _c_ epidermis.

_d_ and _g_ tough and thick part of skin.

_e_ sweat gland.

_f_ blood tubes.

_h_ fat pockets.]

=123. The skin.=--The skin covers the whole body. It is strong and keeps the body from being hurt.

=124. The epithelium.=--The skin is covered with a thin layer of cells like fine scales. These scales are called _epithelium_, or _epidermis_.

They have no blood tubes or nerves and so have no feeling. You can run a pin under them without feeling pain. They are always growing on their under side and wearing off on their upper side. They keep the nerves and blood tubes of the skin from being hurt.

=125. The nails.=--The top scales of epithelium at the ends of the fingers become matted together to make the nails. The nails keep the ends of the fingers from being hurt. They can also be used to hold or cut small things. The new parts of the nails form under the skin and push down the older parts. So the nail grows farther than the end of the finger and needs to be cut off. Biting the nails leaves their ends rough. Then they may catch in the clothes and tear into the tender flesh. We ought to keep the nails cut even with the ends of the fingers.

The nails are not poisonous, but the dirt under them may be. We ought to keep them clean. Clean nails are one mark of a careful boy or girl.

=126. Hair.=--Some of the scales of epithelium over some parts of the body dip into tiny holes in the skin. In each hole they become matted together to form a _hair_. Fine short hair grows on almost every part of the body. On the top of the head it grows long and thick. When boys become men, it also grows long upon their faces. The skin pours out a kind of oil to keep the hair soft and glossy.

[Ill.u.s.tration: =A hair (200).=

_a_ the surface of the skin.

_b_ a hair.

_c_ an oil gland.

_d_ a muscle to make the hair stand on end.

_e_ and _g_, the growing cells of the hair.

_f_ fat in the skin.]

=127. Care of the hair.=--The hair may become dirty like any other part of the body. Brushing it takes out a great deal of dirt, but you should also wash it once a week.

The oil in the skin ought to be enough for the hair. Hair oils do not do the hair any good. If you wet the hair too often, you may make it stiff and take away its gloss. It is best to comb the hair dry. Brush it so as to spread the oil of the skin. Hair dyes are poisonous, and ought not to be used.

=128. The sweat or perspiration.=--The scales of epithelium dip into the skin and there line tiny tubes. The tubes form the _sweat_, or _perspiration_, out of the blood. The tubes are too fine to be seen, but they are upon almost every part of the body. They take the ashes or other waste matter or poisons from the blood and wash them out of the tubes with the perspiration. So the perspiration has two uses.