Everyone has blood inside his body, and when someone cuts himself, a bit of it runs out. This nothing to be frightened about, since each of us has about three or more quarts of blood.

Blood is an interesting fluid. It is composed of red blood cells, white blood cells, little specks of material called platelets, and plasma. Blood cells are also called corpuscles. The plasma is a pale yellow fluid in which the red and white blood corpuscles, and the platelets too, are carried throughout the body inside the arteries and veins. If you have, let us say, three quarts of blood, then a little more than one quart is made up of the red and white cells and a little less than two quarts is made of plasma.

Of course, you know what blood looks like when you cut yourself. But have you ever seen plasma? You probably have. When you skin your knee, for example, you will notice a yellowish fluid ooze from the scrape. That’s plasma. It contains many things, but one of its important functions is to help your blood to clot and form a scab.

Plasma has other important jobs, too. It carries all the absorbed nutriments (the foods we have eaten and have been absorbed) to the tissues. Without plasma, there would be no way for all the nourishing things we have eaten to get to the muscles and other tissues where they are needed. And, finally, it is plasma’s job to carry away from the tissues all the waste products. These are carried by the plasma to the kidneys. The wastes are then gotten rid of by the kidneys in the form of urine, and when we urinate, they are let out of our bodies.

A-white blood cell
B-red blood cell

In addition to plasma, all of us have billions of red blood cells in our bodies. Each cell lives for about two months and is then replaced by a new one. Red cells are formed inside the marrow of our bones. (If you don’t know what marrow is, ask your mother or father to show you the marrow inside of a chicken bone, or a ham bone, or a steak bone.)

The red blood cells have the job of carrying oxygen to all our tissues and of carrying carbon dioxide to our lungs. When we take a deep breath, we breathe in loads of good oxygen from the air, and when we breathe out we get rid of the carbon dioxide that comes from our tissues.

We don’t have as many white cells in our blood as we have red cells, but these white cells are still extremely important to us. They are the cells that fight against infection and disease. They kill the germs and viruses that get into the body when we are sick. Without them, we’d be in pretty bad shape.

Our blood platelets help the blood to clot when it leaves the body. If it weren’t for platelets, when we cut ourselves the blood might keep running, instead of stopping and forming a scab or clot.

And so, blood is very necessary and we should do everything possible to take good care of it. Do you want to know some things you can do to keep your blood healthy?

1. Breathe deeply so that your blood gets a good supply of oxygen from the air and so that your blood can get rid of as much car┬Čbon dioxide as possible.
2. Eat a good diet, especially foods with plenty of iron in them, such as meats, fish, fruits, and vegetables. Iron is needed to keep the red blood cells healthy, so they can take plenty of oxygen to the tissues.
3. Exercise every day, as this will help your blood to flow the way it should to every nook and cranny of your body tissues.
4. Clean every scratch or cut thoroughly. This will help to prevent germs from getting into your bloodstream.
5. Stay in bed as long as you are told to when you’re sick. This will give your white blood cells the best chance to fight and kill the germs that have made you sick.

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