Larger font
Smaller font
  • Results
  • Related
  • Featured
No results found for: "".
  • Weighted Relevancy
  • Content Sequence
  • Relevancy
  • Earliest First
  • Latest First
    Larger font
    Smaller font


    183. What are the capillaries? 1The word capillary signifies a hair, used here to represent hair-sized vessels.HBH 73.5

    They are minute vessels, intermediate between the arteries and veins. They are not a distinct system, but merely fine tubes by which the arteries are continued into the veins.HBH 73.6

    184. What is the size and number of the capillaries?HBH 73.7

    They are of a uniform size, very regular in the distribution of their branches, and their tubes are from one five-hundredth to one six-thousandth of an inch in diameter. It is supposed there are more than one thousand of them to every square inch of the human body. There is no place where you can even prick the body with a pin but you will pierce some of these capillaries, and blood will flow from them.HBH 73.8

    185. What function of the body is accomplished in the capillaries?HBH 74.1

    The capillaries are the most essential parts in the circulation. In the capillary vessels all the organic functions take place. Through them the blood is brought into very near relations with the parts upon which it is to act. It is in the capillaries that the perfect nutrition of the structures takes place: worn-out material is separated, and new material is consolidated. In its passage through the capillary vessels the blood loses its vivifying properties and the florid color it received in the lungs, and becomes dark, impure, and charged with effete matter, resulting from the decomposing particles of tissues. All the waste matter not collected into the excretory passages of the several organs are carried along by the capillaries into the veins, to be purified in passing through the liver and lungs.HBH 74.2

    186. How is the circulation of the blood effected in the capillaries?HBH 74.3

    The circulation in the capillaries seems to be to a great extent independent of the heart’s action, and to be regulated by the organic nerves which preside over the functional process, and distribute the blood to the various parts as needed. The sum of the diameters of the capillary vessels greatly exceeds that of the arteries and veins, which enables the blood in them to move slowly, and even sometimes take a retrograde motion, which greatly helps in the building-up process of the body.HBH 74.4

    187. In what parts of the body are capillaries found?HBH 74.5

    In all parts of the body, except the outer coatHBH 74.6


    of the eye, the tendons, and the nails. They not only serve for the important process of secretion and nutrition, but in them a portion of the animal heat is produced.HBH 75.1

    Figure XI

    188. What is Fig. XI designed to illustrate?HBH 75.2

    The principal veins of the human system.HBH 75.3

    189. What are the veins?HBH 75.4

    The veins are the vessels which return the blood to the heart, after it has been circulated through the various structures of the arteries and capillaries.HBH 75.5

    190. What is the structure of the veins?HBH 75.6

    They have three coats similar to those of the arteries; but they are much thinner than the arteries, and collapse and flatten on becoming empty.HBH 75.7

    191. Where do the veins commence?HBH 75.8

    The veins originate in small radicles, or veins, in all the textures of the body. These empty into larger trunks, those into larger still; the sum of all the radicles being much larger than the main trunk, which facilitates the flow of the blood to the heart, and as the blood is continually coming into a larger channel from small extremities it flows faster and faster, which is just the reverse of the action of the arteries.HBH 75.9

    192. What is the general course of the veins?HBH 76.1

    The larger veins follow the same general course as the large arteries. The smaller veins, however, are much more numerous than the small arteries, and are most abundant just beneath the skin.HBH 76.2

    193. What other difference can you mention between the veins and arteries?HBH 76.3

    While the arteries are elastic, the veins are not. The veins are also furnished with valves in them, which facilitate the flow of the blood to the heart, but almost entirely prevent its flow backward.HBH 76.4

    194. What are the valves of the veins?HBH 76.5

    In the lining membranes of the veins, pouches or bags are formed. They act in the same manner as valves in machinery. The free border of the valvular flap is directed forward, allowing a free current toward the heart, but not in an opposite direction. It was the discovery of these valves in the veins which led Harvey, an English physician, in 1628, to the greater discovery of the circulation of the blood. He inferred that the blood could pass in but one direction through the veins, and consequently in an opposite direction through the arteries. These valves are most numerous in the veins of the extremities. The use of these valves is to prevent the blood, when pressure is made upon the veins, from flowing back into the capillaries. The position of some of these valves can be seen on the back of the hand. By rubbing the skin down with the finger over the vein, the blood is pressed against the valves, distending the veins. If the finger is carried below the valve, the blood is pressed away from it, and the vein between the finger and valve will be empty.HBH 76.6

    195. How many classes of veins are there?HBH 77.1

    There are three classes: sinuses, deep, and superficial. The sinuses are excavations in the structure of an organ, and lined by the internal coat of the veins. There are several of these sinuses in the dura mater of the brain. These run in various directions on the inside of the skull, and most of them empty into the great veins of the neck. They afford a free passage of blood from the brain, even if by excess of arterial action this organ should be overcharged with blood.HBH 77.2

    196. What of the other two classes of veins?HBH 77.3

    The superficial are found near the surface, just under the skin, while the deep veins usually accompany the arteries in pairs, one on each side, and these two courses of veins frequently communicate with each other. They at last unite at the auricle of the heart, into which they pour the blood drained from every part of the body.HBH 77.4

    197. What force carries the blood through the veins?HBH 77.5

    The agencies which are employed to carry the blood through the blood-vessels back to the heart are not so well understood as the action of the arteries. It appears, however, aside from that help derived from the suction of the heart and the aid of the vein-valves, that the blood is helped on its way through the veins by the action of the muscles about the veins, and temporary pressure upon the surface of the body; so light rubbing occasionally of the surface of the body must facilitate the circulation of the blood. The affinity of venous blood for oxygen is supposed by some to cause it to urge its way on to the heart and lungs. It is probable that the great principle moving it onward is the direct controlling influence of the organic nerves, which are everywhere present in these veins.HBH 77.6

    198. What are the pulmonary veins?HBH 78.1

    They are the veins which return the pure or arterial blood from the lungs to the left auricle of the heart. These veins are four in number, and they differ from the veins in general, in being but little larger than their corresponding arteries, and in accompanying, singly, each branch of the pulmonary artery.HBH 78.2

    199. What are the veins which are called the Portal System?HBH 78.3

    It comprises those vessels which receive their blood from the intestinal canal, the stomach, the spleen, etc. These small vessels unite into a larger trunk, and, instead of passing directly to the heart, they form what is called the portal vein, which passes into every part of the liver, where the blood is again collected by a series of vessels which convey the blood to the heart. By this means the blood which passes from the bowels, etc., to the heart, is strained, and prepared to enter into the general circulation; with the other venous blood, it is forced into the lungs, and from the heart out again through the system.HBH 78.4

    200. What are the component parts of the blood?HBH 78.5

    If the blood be examined microscopically when first drawn, it appears to be made up of a transparent liquid called serum, or plasma, and a number of circular bodies, mostly of a red color, called corpuscles, or minute bodies. The material of the blood is albumen, fibrin, and several salts, some of which are found in distinct crystals. When the blood is exposed alternately to the action of oxygen and carbonic acid, these red corpuscles lose their circular form, and become star-shaped, and are finally destroyed; it is calculated that millions of them are thus destroyed at each pulsation of the heart.HBH 78.6

    201. What is the color of the blood?HBH 79.1

    The blood if drawn from an artery is of a bright red color; but if drawn from a vein it is purple. This color is caused by the impurities in the blood. The odor of the blood is the same as the breath of the animal from which it is taken.HBH 79.2

    202. Are there any other substances connected with the blood?HBH 79.3

    Yes; the waste substances produced by the action of organs, and the nutritive material adapted to replace the waste.HBH 79.4

    203. How much blood is there in an ordinary-sized human body?HBH 79.5

    From three to four gallons. Of this, from one-fourth to one-third is supposed to be in the arteries; from two-thirds to three-fourths in the veins; a large proportion of the whole being in the arterial and venous capillary vessels. The blood weighs some 30 pounds in a person weighing 150 pounds.HBH 79.6

    204. How long does it take for all the blood to make a circuit through the system?HBH 79.7

    This depends on the health of the person, and the amount of exercise taken. It is supposed that an amount of blood equal in weight to all in the body makes its circuit in from three to eight minutes. The blood is thrown in an instant from the heart to the extremities, but its passage back, as already shown, is slower.HBH 80.1

    205. How much blood passes through the heart in twenty-four hours?HBH 80.2

    Not far from ten thousand pounds, or five tons, equal in weight to about seventy men.HBH 80.3

    206. What is necessary to a healthy condition of all parts of the body?HBH 80.4

    A healthy circulation to all those parts. If the system is supplied with pure blood, and that circulates properly to every organ, it is health.HBH 80.5

    207. What is absolutely essential to promote a proper circulation of the blood?HBH 80.6

    It is necessary to pay special regard to the clothing, to see that the limbs and arms, hands and feet, are properly and sufficiently clothed. If the clothing is too scanty on these parts the blood is chilled, which greatly retards its circulation; the efforts of the heart are also increased to carry the vital current to the suffering parts, which is a needless and unnatural wear of that organ. It is important also that the clothing should be worn loosely upon the body, as much pressure upon the body prevents the rapid flow of the blood from the extremities to the heart. Many instances of persons suffering with cold feet might be almost if not entirely cured by wearing loose boots or shoes of sufficient thickness, instead of such thin and delicate tight ones as some now wear.HBH 80.7

    208. What can you say of proper food, as effecting the circulation, and the building up of the system?HBH 81.1

    As the blood is made from and of the alimentary substance contained in our food, and the quality of that aliment depends on the quality of the food eaten, so, if we would have our blood properly freighted with suitable nutriment, and our body kept in a healthy condition, it becomes a matter of the highest importance that we give the most scrupulous care and attention to the proper selection of our food. And also to select that kind of food which our system can most readily digest and assimilate to its own uses. Otherwise we cause a useless wear of the system, and thus shorten our lives.HBH 81.2

    209. Are there many diseases of the circulating organs?HBH 81.3

    These organs, though constantly in use, and easily excited by muscular movement and mental emotion, are affected with but few diseases. Many diseases, called disease of the heart, are merely sympathetic affections, and the real disease and difficulty lies in other organs. Heart diseases are most common late in life, at about sixty years of age. Those persons who have any tendency to disease of the heart, either real or sympathetic, should be on their guard against sudden exertions, and, to as great an extent as possible, avoid mental anxiety, grief and alarm, as these all tend to increase such difficulties.HBH 81.4

    Larger font
    Smaller font