Page images
PDF
EPUB

VEINS AND ARTERIES.

67

These move as easily as a door closes on its hinges, and prevent the return of the blood.

12. The arteries are larger than the veins, and lie deeper in the system, or more removed from the surface. They serve to carry the blood out of the heart, and to distribute the proper nourishment where it is required. The veins are more numerous, and smaller in size than the arteries, and bring the blood to the heart.

13. There was great wisdom manifested by our Maker in locating these different vessels; for if we accidentally cut a vein, there is not much danger; but if an artery be severed, and the ends are not immediately tied, death will be the result.

66

14. You will hear physicians frequently speak of feeling the pulse ;" and, for that purpose, take hold of the wrist. All they mean, is, that they wish to know how rapidly the blood passes or circulates, and as the artery at the wrist is nearer the surface than any other, it can be relied on with more certainty, although the blood does not flow through this one, more rapidly than through the others.

15. By palpitation of the heart, we mean that there is some obstruction in the way, which makes the circulation irregular. Our lives and existence depend on the regular circulation of the blood; hence, this palpitation is considered very dangerous. We ought not to

12. Describe the arteries, and their use. Describe the veins, and their specific purpose. 13. How was the wisdom of our Maker displayed? Do the veins or arteries require the most care, and why? 14. What is meant by "feeling the pulse ?" Why do physicians always judge of the condition of the body by the artery at the wrist? 15. What is meant by the palpitation of the heart? Why is palpitation considered dangerous?

breathe the same air the second time; for if we do, it will not then contain sufficient oxygen to produce that change necessary for good blood.

16. In order to have as pure air as possible, we should ventilate our rooms, especially those in which we sleep. When the blood is taken from the body, and exposed to the air, it becomes thick, or coagulates; little yellowish particles of fluid arise, which are called the serum; a thick substance is left, which, when washed, loses its red appearance, and becomes white; this is called the fibrine of the blood. It is supposed by many that there is iron in the blood, which gives the red color to these particles; and when some are called iron-hearted, it is said that they have more than the usual quantity.

17. We are, however, at liberty to doubt this if we choose. You have all heard of consumption. This means that the lungs are consumed, or incapable of inhaling a sufficient quantity of air to support life. This disease, which causes the death of many dear friends, is produced by exposure to the cold, wearing thin shoes in cold and damp weather, and by drawing the clothes so tightly around the ribs that they crowd in and destroy the lungs; this might be prevented in a variety of cases by proper care and attention.

18. Dr. Harvey, an Englishman, made the discovery of the circulation of the blood in the year 1620. For

15. Why should we not breathe the same air twice? 16. How can we obtain pure air? What rooms especially require ventilation? What change takes place in the blood when it is exposed to the air? What is the serum, and what is its color? Describe the fibrine and its appearWhat other elements do some suppose is contained in the blood? Is there always the same quantity of iron? 17. What is consumption? How is this disease produced? How can consumption be avoided? 18. Who discovered the circulation of the blood? In what year ?

ance.

CIRCULATION OF THE BLOOD.

69

many years he durst not let the public know his ideas and opinions on this subject; and when he did, he was much opposed, very few believing his new principles.

19. Nearly every discovery that has been made in physiology or philosophy has met with very bitter opposition when first introduced. Some will not believe any new doctrine, even when there are light and evidence enough to prove it to be correct, but adhere tenaciously to the old system of things. But Harvey lived long enough to see his principles admitted by the scientific; and though he was much persecuted for many years, yet he had the pleasure to know that he was correct in his belief. Among the many proofs which led him to make this discovery were the following.

20. First; If the chest of a cold-blooded animal, a toad or a frog, be opened, the heart can be seen to contract and dilate. Then it remains an instant at rest, and again dilates and contracts, and raises itself a little, the same as in our own bodies, and causes beating. There would be no cause for this expansion and contraction, if the blood did not flow in and pass out of the heart.

21. Secondly; Another reason is, that in all the arteries there are valves, which permit the blood to pass into them, but prevent its passage backward toward the heart; also, in all the veins, the valves allow the blood to go toward the heart, but not in the opposite direction;

18. Did he make his discovery known? in science been received by the public?

19. How has every discovery To what do some always adhere? Was the opposition and prejudice finally removed? 20. What was the first proof of the circulation of the blood? 21. What was the second proof of the circulation of the blood?

which facts alone would clearly prove to every candid mind, that they would not have been constructed in this manner, and so well adapted for the circulation of the blood, unless it were for that specific purpose, and for that alone.

22. Thirdly; It has been said that the circulation of the blood through the veins and arteries may be seen by a microscope-an instrument by which the smallest object may be seen-in some of the delicate parts of different animals, as in the web of a frog's foot.

23. Fourthly; The way in which bleeding from a vein is performed, is another proof of the circulation of the blood. A tight bandage is placed around the arm above the place where the vein is to be opened. The blood in returning through it toward the heart, is interrupted in its passage, and as the artery underneath is not compressed, the vein is filled with blood, and is swelled. If the vein be then opened below the bandage, the blood will flow freely; but if the bandage be tight enough to compress the artery, the blood cannot pass through it from the heart, so there will soon be none in the vein; or, if the opening be made above the bandage no blood is obtained.

24. Fifthly; In the amputation, or cutting off, of a limb, the surgeon ties only the ends of the arteries together. As these carry the blood from the heart to all parts of the body, the patient would soon bleed so as to cause

21. What should the present construction of the veins and arteries prove clearly? 22. What is the third proof of the circulation of the blood? What is a microscope? 23. What is the fourth proof of the circulation of the blood? How is bleeding from a vein performed? What would be the result if the bandage be too tightly bound? 24. What is the fifth proof of the circulation of the blood? Why do not the veins require to be tied?

[ocr errors]
[blocks in formation]

death, unless some means were taken to prevent it. The veins which carry the blood back to the heart do not bleed, and therefore need not be tied.

25. From these live reasons or proofs of Dr. Harvey, we cannot but believe that the blood passes from the heart, through the arteries, into the veins, and is returned by them into the heart; or, in other words, that the blood continually circulates, or is distributed through our bodies.

25. To what conclusion should these five reasons of Dr. Harvey lead us?

« PreviousContinue »