First Book in Physiology and Hygiene by J. H. Kellogg (books to read as a couple .TXT) 📖
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2. Irritating substances and things which are not foods should not be eaten.
3. The teeth must be carefully used and kept clean.
4. Tobacco-using does the stomach harm, and sometimes causes cancer of the mouth.
5. Alcohol injures the gastric juice, and causes disease of the stomach and the liver.
CHAPTER X. A DROP OF BLOOD.1. The Blood.—Did you ever cut or prick your finger so as to make it bleed? Probably you have more than once met with an accident of this sort. All parts of the body contain blood. If the skin is broken in any place the blood flows out.
2. How many of you know what a microscope is? It is an instrument which magnifies objects, or makes them look a great deal larger than they really are. Some microscopes are so powerful that they will make a little speck of dust look as large as a great rock.
3. The Blood Corpuscles.—If you should look at a tiny drop of blood through such a microscope, you would find it to be full of very small, round objects called blood corpuscles.
4. You would notice also that these corpuscles are of two kinds. Most of them are slightly reddish, and give to the blood its red color. A very few are white.
5. Use of the Corpuscles.—Do you wonder what these peculiar little corpuscles do in the body? They are very necessary. We could not live a moment without them. We need to take into our bodies oxygen from the air. It is the business of the red corpuscles to take up the oxygen in the lungs and carry it round through the body in a wonderful way, of which we shall learn more in a future lesson.
6. The white corpuscles have something to do with keeping the body in good repair. They are carried by the blood into all parts of the body and stop where they are needed to do any kind of work. They may be compared to the men who go around to mend old umbrellas, and to do other kinds of tinkering. It is thought that the white corpuscles turn into red ones when they become old.
7. The corpuscles float in a clear, almost colorless fluid which contains the digested food and other elements by which the body is nourished.
SUMMARY.1. The blood contains very small objects called blood corpuscles.
2. There are two kinds of corpuscles, red and white.
3. The red corpuscles carry oxygen.
4. The white corpuscles repair parts that are worn.
5. The corpuscles float in a clear, almost colorless fluid, which nourishes the body.
CHAPTER XI. WHY THE HEART BEATS.1. If you place your hand on the left side of your chest, you will feel something beating. If you cannot feel the beats easily, you may run up and down stairs two or three times, and then you can feel them very distinctly. How many of you know the name of this curious machine inside the chest, that beats so steadily? You say at once that it is the heart.
THE HEART.
2. The Heart.—The heart may be called a live pump, which keeps pumping away during our whole lives. If it should stop, even for a minute or two, we would die. If you will place your hand over your heart and count the beats for exactly one minute, you will find that it beats about seventy-five or eighty times. When you are older, your heart will beat a little more slowly. If you count the beats while you are lying down, you will find that the heart beats more slowly than when you are sitting or standing. When we run or jump, the heart beats much harder and faster.
3. Why the Heart Beats.—We have learned in preceding lessons that the digested food is taken into the blood. We have also learned that both water and oxygen are taken into the blood. Thus the blood contains all the materials that are needed by the various parts of the body to make good the wastes that are constantly taking place. But if the blood were all in one place it could do little good, as the new materials are needed in every part of the body. There has been provided a wonderful system of tubes running through every part of the body. By means of these tubes the blood is carried into every part where it is required. These tubes are connected with the heart. When the heart beats, it forces the blood through the tubes just as water is forced through a pipe by a pump or by a fire-engine.
4. The Heart Chambers.—The heart has four chambers, two upper and two lower chambers. The blood is received into the upper chambers, and is then passed down into the lower chambers. From the lower chambers it is sent out to various parts of the body.
THE INSIDE OF THE HEART.
5. The Blood-Vessels.—The tubes through which the blood is carried are called blood-vessels. There are three kinds of blood-vessels. One set carry the blood away from the heart, and are called arteries (ar'-te-ries). Another set return the blood to the heart, and are called veins. The arteries and veins are connected at the ends farthest from the heart by many very small vessels. These minute, hairlike vessels are called capillaries (cap'-il-la-ries).
6. The Arteries.—An artery leads out from the lower chamber of each side of the heart. The one from the right side of the heart carries the blood only to the lungs. The one from the left side of the heart carries blood to every part of the body. It is the largest artery in the body, and is called the aorta. Soon after it leaves the heart the aorta begins to send out branches to various organs. These divide in the tissues again and again until they become so small that only one corpuscle can pass through at a time, as shown in the colored plate. (Frontispiece.)
7. The Veins.—These very small vessels now begin to unite and form larger ones, the veins. The small veins join to form larger ones, until finally all are gathered into two large veins which empty into the upper chamber of the right side of the heart. The veins which carry blood from the lungs to the heart empty into the upper chamber of the left side of the heart.
8. What is Done in the Blood-Vessels.—While the blood is passing through the small blood-vessels in the various parts of the body, each part takes out just what it needs to build up its own tissues. At the same time, the tissues give in exchange their worn-out or waste matters. The red blood corpuscles in the capillaries give up their oxygen, and the blood receives in its stead a poisonous substance called carbonic-acid gas.
9. Red and Blue Blood.—While in the arteries the blood is of a bright red color; but while it is passing through the capillaries the color changes to a bluish red or purple color. The red blood is called arterial blood, because it is found in the arteries. The purple blood is called venous blood, because it is found in the veins. The loss of oxygen in the corpuscles causes the change of color.
10. Change of Blood in the Lungs.—Exactly the opposite change occurs in the blood when it passes through the lungs. The blood which has been gathered up from the various parts of the body is dark, impure blood. In the lungs this dark blood is spread out in very minute capillaries and exposed to the air. While passing through the capillaries of the lungs, the blood gives up some of its impurities in exchange for oxygen from the air. The red corpuscles absorb the oxygen and the color of the blood changes from dark purple to bright red again. The purified blood is then carried back to the upper chamber of the left side of the heart through four large veins. The blood is now ready to begin another journey around the body.
11. The Pulse.—If you place your finger on your wrist at just the right spot, you can feel a slight beating. This beating is called the pulse. It is caused by the movement of the blood in the artery of the wrist at each beat of the heart. The pulse can be felt at the neck and in other parts of the body where an artery comes near to the surface.
12. How much Work the Heart Does.—The heart is a small organ, only about as large as your fist, and yet it does an amount of work which is almost beyond belief. Each time it beats, it does as much work as your arm would do in lifting a large apple from the ground to your mouth. It beats when we are asleep as well as when we are awake. When we run we know by the way in which it beats that it is working very fast. Do you know how much a ton is? Well, in twenty-four hours the heart does as much work as a man would do in lifting stones enough to weigh more than one hundred and twenty tons.
13. The Lymphatics.—While the blood is passing through the capillaries, some of the white corpuscles escape from the blood-vessels. What do you suppose becomes of these runaway corpuscles? Nature has provided a way by which they can get back to the heart. In the little spaces among the tissues outside of the blood-vessels very minute channels called lymph channels or lymphatics (lym—phat'-ics) begin. The whole body is filled with these small channels, which run together much like the meshes of a net. In the centre of the body the small lymphatics run into large ones, which empty into the veins near the heart. This is the way the stray white blood corpuscles get back into the blood.
LYMPH GLAND AND VESSELS.
14. The Lymph.—In the lymph channels the white corpuscles float in a colorless fluid called lymph. The lymph is composed of the fluid portion of the blood which has soaked through the walls of the small vessels. The chief purpose of the lymphatics is to carry the lymph from the tissues back to the heart.
15. Lymphatic Glands.—Here and there, scattered through the body, are oval structures into each of which many lymphatic vessels are found to run, as shown in the illustration. These are called lymphatic glands.
16. The heart and blood-vessels are among the most wonderful structures in the body. It is no wonder, then, that alcohol, tobacco, and other narcotics and stimulants produce their most deadly effects upon these delicate organs. What these effects are we shall learn more fully in the next chapter.
1. The heart beats to circulate the blood.
2. The heart has four chambers, two upper and two lower.
3. There are tubes called blood-vessels which carry the blood to all parts
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