Applied Physiology Part 5

=70. Beer.=--After man had made wine for a long time, some one found out how to cultivate yeast. Then men could make sugar and water ferment whenever they wanted to. So men boiled grain to take out its sugar. Then they poured off the liquor and added yeast and let it ferment. This made beer and ale. Now millions of bushels of grain are used every year in making beer. Men call beer a _light_ drink. But it has alcohol and is a strong drink, and can make men drunk.

=71. Root beer.=--Some persons boil roots and herbs, and add mola.s.ses and yeast. Then the liquid ferments and becomes _root beer_. They say "it has no alcohol, for we made it." But it does have alcohol, for yeast always makes alcohol. Some ginger ale is made by putting yeast in sweetened ginger water. It has alcohol, too.

=72. Distillation.=--Boiling water turns to vapor or steam and goes off in the air. When the vapor is cooled, you can see the water again.

It often cools on the window and makes little streams of water. You can catch the steam in a tube. If you keep the tube cool, the steam will turn to water in the tube. This process is called _distillation_.

[Ill.u.s.tration: =A gla.s.s of whisky contains so much alcohol.=]

Boiling alcohol also pa.s.ses off into the air as vapor. When the vapor is cooled, it becomes liquid again. Alcohol boils with less heat than water. When alcohol in water is heated, the alcohol boils first. So the vapor has more alcohol than the water. When the vapor is cooled, the liquid has more alcohol than it had at first. When the liquid is distilled again it has more alcohol yet. Pure alcohol can be made in this way.

=73. Whisky.=--Distilling wine or strong beer makes _whisky_ and _brandy_. Whisky is one half alcohol. It is more harmful than wine or beer.

=74. Habit.=--Some strong drinks have only a little alcohol and some have a great deal. No one begins to drink the strong liquors. He begins with wine or beer. When he has once learned, he has a hard time to stop drinking. It is dangerous to drink even weak drinks.

=75. Strong drink and thirst.=--When a man is thirsty, water will satisfy him but strong drink will not. Sometimes the mouth is dry and dirty and then a man feels thirsty. Rinsing the mouth with water, and rubbing the tongue and teeth clean will help the dryness and stop the thirst. At any rate, strong drink will only make the mouth dryer.

Some men drink only when they are tired. Then a cup of strong and hot tea or coffee will make them feel much better than a gla.s.s of strong drink, and will not harm them so much.

When strong drink is swallowed, its alcohol takes water from the mouth. When your mouth is dry, you feel thirsty. Strong drink makes the mouth dry, and so a drink makes a man more thirsty. The alcohol also makes the mouth smart. Men need another drink to cool the mouth after the first one. So one drink leads to another. All the while a person drinks water with the alcohol until he has too much water. But his mouth is dry and he feels as thirsty as ever.

=76. Effect of alcohol upon the stomach.=--When strong drink is swallowed it makes the stomach smart just as it does the mouth. So the stomach feels warm, but it is really no warmer. This harms the stomach and keeps it from working well.

Alcohol also keeps the gastric juice from changing alb.u.min to a liquid. Alcohol keeps flesh from decaying in a museum. In the same way it may hinder the digestion of food in the stomach.

When alcohol is used for only a short time, the stomach can get well; but if it is used for months and years, the stomach will stay weak.

Then the drinker can hardly eat at all.

=77. What becomes of alcohol.=--In the stomach a great deal of gastric juice is mixed with the alcohol. So it is very weak when it reaches the intestine. Alcohol needs only a little digesting. It soon soaks into the blood from the intestine along with the other food. The blood flows fast and washes the alcohol away as soon as it leaves the intestine. Too little gets into the blood at once to harm it much.

Alcohol goes to the liver, and is there destroyed; but it still does great harm. The liver has to attend to the alcohol, and so it does not change the food to good blood, and it does not take all the poisons out of the blood. Then the whole body becomes weak and sick. Alcohol hurts the liver first, and more than other parts of the body. On this account, drinkers often have bilious attacks and stomach troubles.

=78. Bitters.=--Many medicines are made by dissolving drugs in alcohol. In taking a strong medicine, we use only a few drops, and so do not get much alcohol. Some kinds of medicines must be taken in large doses. Bitters are weak medicines, and must be taken by the tablespoonful. A tablespoonful of the medicine has more alcohol than a large drink of whisky. The bitters seem to make a person feel well, but it is because he is taking a large amount of strong drink.

Jamaica Ginger is only common ginger dissolved in alcohol. It, too, is a form of strong drink.

=79. Strong drink as medicine.=--People sometimes keep whisky or brandy in the house to give for colds or other slight forms of sickness. A drink of hot coffee does more good than the strong drink, and has none of its dangers.

By using whisky or brandy for medicine, children learn to believe in strong drink, and so they will be likely to use it when they grow up.

This reason alone ought to keep any one from giving it to a child.

=80. Alcohol in cooking.=--In making bread, alcohol is formed in the dough by the yeast. When the bread is baked, all the alcohol is driven off by the heat, and so we do not eat any.

Sometimes brandy or wine is put into desserts. If it is put in after the dessert is cooked, we shall get as much alcohol as if we had drunk it. If the liquor is put in before cooking, the heat will drive off the alcohol but the flavor of the liquor will remain. The flavor will do no harm in itself, but people will learn its taste, and from it may learn to like the strong drink itself. The alcohol in bread has no special flavor and does not leave any taste behind. So we cannot learn to like strong drink by eating bread.

WHAT WE HAVE LEARNED

1. Fruit juice makes wine or cider.

2. All kinds of wine contain alcohol.

3. When the liquid from boiled grain has fermented, it becomes beer, or ale.

4. By boiling wine or beer, and cooling the vapor, distilled drinks like whisky are made. They are one half alcohol.

5. Water will satisfy a real thirst. Strong drink will not.

6. Alcohol keeps the stomach from digesting food.

7. Alcohol soaks into the blood tubes and goes to the liver.

8. The liver destroys the alcohol, but is hurt in doing it.

CHAPTER IX

THE BLOOD

=81. Blood.=--After food becomes blood, it goes to every part of the body to feed the cells. Even a pin p.r.i.c.k anywhere in the body draws blood. The blood makes the skin pink. There are five or six quarts of blood in a man's body. This is about 1/13 of his body.

[Ill.u.s.tration: =Blood corpuscles (400).=

_a_ a pile of red blood cells.

_b_ red blood cells seen flatwise.

_c_ red blood cells seen edgewise.

_d_ white blood cells.]

Blood looks like a red liquid. But if you look at it through a strong microscope, it looks like water, and millions of little red cells.

These cells carry air through the body. They make the blood look red.

There are also a smaller number of white cells. Blood is made of red cells, white cells, and a liquid.

=82. The liquid in blood.=--The liquid part of the blood is alb.u.min, and water, with a little fat, sugar, and minerals. It is food and drink for the cells of the body. When blood is drawn from the body it soon becomes like jelly. We call the jelly a _clot_. When you cut your finger, a clot forms in the cut and plugs up the bleeding place. If it did not, the blood would all run out of the body and we should die.

[Ill.u.s.tration: =Diagram of the heart while it is beating.=

_a_ vein entering the auricle.

_b_ auricle.

_c_ closed valve to keep blood from flowing back into the auricle.

_d_ ventricle.

_e_ artery.

_f_ valve to keep blood from returning to the ventricle.]

=83. The heart.=--The blood is held in tubes. A pump inside the body keeps it always moving. This pump is called the _heart_. The heart is a bag of muscle with thick sides. It is about as large as your fist.

When it is full, it has the power to make itself smaller, and so it squeezes the blood out through a tube. We can feel each squeeze as a heart-beat. You can find the heart-beat just to the left of the middle of the body about two hand-breadths below the neck.

=84. The heart-beat.=--A man's heart beats about seventy times each minute. Boys' and girls' hearts beat much faster. Running or hard work of any kind makes the heart beat faster yet. Your heart will keep on beating until you die. It does not seem to rest at all, yet it works only while you feel it beat. Between each beat it rests while the blood is filling it again. So it really rests one half of the time.