475. Respiration, or breathing, is that process by which air is taken into the lungs and expelled from them. The object of respiration is, 1st. To supply the system with oxygen, which is essential to the generation of animal heat; 2d. To convert the chyle into blood. This is done by the oxygen of the inspired air; 3d. To relieve the organs of the body of the principal elements (carbon and hydrogen) that compose the old and useless particles of matter. The organs of the system, as already mentioned, are principally composed of carbon, hydrogen, oxygen, and nitrogen.
476. By the action of the lymphatics and capillary veins, the old and worn-out particles are conveyed into the veins of the systemic circulation. The hydrogen, in form of watery vapor, is easily discharged in the perspiration and other secretions. The nitrogen and oxygen are, or may be, separated from the blood, through the agency of several different organs; but carbon does not escape so readily. It is probable that a part of the surplus carbon of the venous blood is secreted by the liver; but a far greater amount passes to the lungs, and these may be considered as special organs designed to separate this element from the venous blood.
477. An ordinary inspiration may be accomplished by the action of the diaphragm, and a slight elevation of the ribs. In 218 full inspiration, the diaphragm is not only more depressed but the ribs are evidently elevated. To produce this effect on the ribs, two sets of muscles are called into action. Those which are attached to the upper rib, sternum, and clavicle, contract and elevate the lower and free extremities of the ribs. This enlarges the cavity of the chest between the spinal column and the sternum. But the lateral diameter, in consequence, is only slightly increased, because the central portion of the ribs sinks lower than their posterior extremities, or their cartilaginous attachment to the sternum.
475–494. Give the physiology of the respiratory organs. 475. What is respiration? What is the principal object in breathing? 476. How are the useless atoms of matter conveyed into the veins of the systemic circulation? How may the principal elementary substances be separated from the blood? 477. How may an ordinary inspiration be accomplished?
Fig. 95.
Fig. 95. 6, Four of the vertebræ, to which are attached three ribs, (7, 7, 7,) with their intercostal muscles, (8, 8.) These ribs, in their natural position, have their anterior cartilaginous extremity at 4, while the posterior extremity is attached to the vertebræ, (6,) which are neither elevated nor depressed in respiration. 1, 1, and 2, 2, parallel lines, within which the ribs lie in their natural position. If the anterior extremity of the ribs is elevated from 4 to 5, they will not lie within the line 2, 2, but will reach the line 3, 3. If two hands extend from 1, 1, to 2, 2, they will effectually prevent the elevation of the ribs from 4 to 5, as the line 2, 2, cannot be moved to 3, 3.
What effect has a full inspiration on the ribs and diaphragm? How is the chest enlarged between the spinal column and sternum? What is said of the lateral diameter of the chest? Explain fig. 95.
478. The central portion of the ribs is raised by the action of intercostal muscles. The first, or upper rib, has but little movement; the second has more motion than the first, while 219 the third has still more than the second. The second rib is elevated by the contraction of the muscles between it and the first. The third rib is raised by the action of two sets of muscles; one lies between the first and second ribs, the other between the second and third. The motion of each succeeding rib is increased, because it is not only acted upon by the muscles that move the ribs above, but by an additional intercostal; so that the movement of the twelfth rib is very free, as it is elevated by the contraction of eleven muscles.
479. The tenth rib is raised eight times as much as the second rib, and the lateral diameter of the lower portion of the chest is increased in a corresponding degree. At the same time, the muscular margin of the diaphragm contracts, which depresses its central portion; and in this way, the chest is enlarged forward, laterally, and downward, simultaneously with the relaxation of the walls of the abdomen.
480. The lungs follow the variations of capacity in the chest, expanding their air-cells when the latter is enlarged, and contracting when the chest is diminished. Thus, when the chest is expanded, the lungs follow, and consequently a vacuum is produced in their air-cells. The air then rushes through the mouth and nose into the trachea and its branches, and fills the vacuum as fast as it is made. This mechanical process constitutes inspiration.
481. After the expansion of the chest, the muscles that elevated the ribs relax, together with the diaphragm. The elasticity of the cartilages of the ribs depresses them, and the cavity of the chest is diminished, attended by the expulsion of a portion of the air from the lungs. At the same time, the muscles that form the front walls of the 220 abdominal cavity, contract, and press the alimentary canal, stomach, and liver, upward against the diaphragm; this, being relaxed, yields to the pressure, rises upward, and presses upon the lungs, which retreat before it, and another portion of air is expelled from these organs. This process is called expiration.
478. Describe the action of the intercostal muscles upon the ribs. 479. How does the elevation of the tenth rib compare with the second? What effect has this elevation upon the lateral diameter of the chest? 480. Describe the process of inspiration. 481. Describe the process by which the air is forced out of the lungs.
Fig. 96.
Fig. 96. A front view of the chest and abdomen in respiration. 1, 1, The position of the walls of the chest in inspiration. 2, 2, 2, The position of the diaphragm in inspiration. 3, 3, The position of the walls of the chest in expiration. 4, 4, 4, The position of the diaphragm in expiration. 5, 5, The position of the walls of the abdomen in inspiration. 6, 6, The position of the abdominal walls in expiration.
482. Thus it is obvious that the enlargement of the chest, or inspiration, is produced in two ways: 1st. By the depression of the convex portion of the diaphragm; 2d. By the elevation of the ribs. On the contrary, the contraction of the 221 chest, or expiration, is produced by the depression of the ribs, and elevation of the central part of the diaphragm. These movements are successive during life, and constitute respiration.
Explain fig. 96. 482. In how many ways may the chest be enlarged, and how is it accomplished? How is the contraction of the chest effected?
Fig. 97.
Fig. 97. A side view of the chest and abdomen in respiration. 1, The cavity of the chest. 2, The cavity of the abdomen. 3, The line of direction for the diaphragm when relaxed in expiration. 4, The line of direction for the diaphragm when contracted in inspiration. 5, 6, The position of the front walls of the chest and abdomen in inspiration. 7, 8, The position of the front walls of the abdomen and chest in expiration.
Experiment. Place the ear upon the chest of a person, and a murmuring sound will be heard, somewhat like the soft sighings of the wind through forest trees. This sound is 222 caused by the air rushing in and out of the lungs, and is peculiarly distinct in the child.
Explain fig. 97. How may the murmur of respiration be heard?
483. It is not easy to decide how much air is taken into the lungs at each inspiration. The quantity, however, must vary in different individuals, from the difference in the condition and expansion of the lungs, together with the size of the chest. From numerous experiments, the quantity, at an ordinary inspiration, of a common-sized man, is fixed at forty cubic inches. It has been estimated that one hundred and seventy cubic inches can be thrown out of the lungs by a forcible expiration, and that there remain in the lungs two hundred and twenty cubic inches; so that these organs, in their quiescent state, may be considered as containing about three hundred and ninety cubic inches of air, or more than a gallon.
484. Respiration is more frequent in females and children than in adult men. In diseases, particularly those of the lungs, it is more increased in frequency than the action of the heart. In health, the smallest number of inspirations in a minute by an adult, is not less than fourteen, and they rarely exceed twenty-five. Eighteen may be considered an average number. The quantity of oxygen taken into the lungs at each inspiration is about eight cubic inches, one half of which disappears in every act of respiration.
Observation. Under different circumstances, however, the consumption of oxygen varies. It is greater when the temperature is low, than when it is high; and during digestion the consumption has been found one half greater than when the stomach was empty.
483. Can it be ascertained with accuracy how much air is taken into the lungs at each inspiration? Why not? What is the probable quantity that an ordinary sized man inspires? How much can be thrown out of the lungs at a forcible expiration, and how much remains in the lungs? From these calculations, how much may they contain in their quiescent state? 484. In whom is respiration most frequent? How in disease? How in health? How many may be considered an average number? When is the consumption of oxygen the greatest?
485. Dr. Southwood Smith has lately performed a series of very interesting experiments, from which he deduces the following general results: “1st. The volume of air ordinarily present in the lungs is about twelve pints. 2d. The volume of air received by the lungs at an ordinary inspiration is one pint. 3d. The volume of air expelled from the lungs at an ordinary expiration, is a little less than one pint. 4th. Of the volume of air received by the lungs at one inspiration, only one fourth part is decomposed at one action of the heart. 5th. The quantity of blood that flows to the lungs, to be acted upon by the air at one action of the heart, is two ounces, and this is acted on in less than one second of time. 6th. The quantity of blood in the whole body of the human adult, is twenty-five pounds avoirdupois, or twenty pints. 7th. In the mutual action that takes place between the air and blood, every twenty-four hours, the air loses thirty-seven ounces of oxygen, and the blood fourteen ounces of carbon.”
486. Apparently, atmospheric air is a simple element. But chemical analysis shows its composition to be oxygen and nitrogen, in the proportion of twenty-one parts of the former, and about seventy-nine of the latter. In addition, there is a small amount of vapor of water and carbonic acid. The pressure of this invisible, elastic fluid upon the body of an ordinary sized adult, is estimated to equal thirty-five thousand pounds.
487. The principal substance of a vitiated character in the dark-colored blood is carbonic acid. And since there is no chemical affinity between the oxygen and nitrogen of the air, the former readily unites with some of the elements of the blood. Hence, whenever blood is presented to the 224 air in the lungs, the oxygen leaves the nitrogen, and becomes mixed with the circulating fluid. (Appendix J.)
485. State the 1st, 2d, 3d, and 4th deductions from the experiments of Dr. Southwood Smith. The 5th, 6th, and 7th. 486. Of what is atmospheric air composed? What is the weight of air upon a common sized man? 487. What is the principal substance of a vitiated character in the dark-colored blood? What is said of the chemical affinity between oxygen and nitrogen?
488. Again, carbonic acid and water have a stronger affinity for atmospheric air than for the other elements of the blood. Consequently, when they are brought into contact with the air in the lungs, the carbonic acid and water leave the other constituents of the blood, and unite with the air. In this way the bluish, or impure blood is relieved of its impurities, and becomes the red, or pure blood, which contains the principles so essential to life. (Appendix K.)
489. The formation of carbonic acid and water, eliminated from the system through the lungs and skin, is explained by the following theory: In the lungs and upon the skin the oxygen separates from the nitrogen and unites with the blood in the capillary vessels of these organs. The oxygen is conveyed with the blood to the capillary arteries and veins of the different tissues of the system. In these membranes there is a chemical union of the oxygen with the carbon and hydrogen contained in the blood and waste atoms of the system. This combustion, or union of oxygen with carbon and hydrogen, is attended with the disengagement of heat, and the formation of carbonic acid and water. (Appendix L.)
490. The following experiment will illustrate the passage of fluids through membranes, and the different affinity of gases for each other. Put a mixture of water and alcohol into a phial and leave it uncorked. Both the water and alcohol have a greater affinity for air than for each other. Alcohol has a greater affinity for the air, and will be diffused through it more readily than the water, when there is no intervening obstacle. But tie a piece of bladder over the mouth of the phial, and let it stand a few days,—the water 225 will leave the alcohol, and pass through the membrane. By the aid of this experiment, we shall endeavor to explain the interchange of fluids in the lungs.
488. What is formed when oxygen unites with carbon or hydrogen? 489. Give the theory for the formation of carbonic acid and watery vapor thrown out of the system. 490. Illustrate the passage of fluids through membranes, and the different affinities of gases.
491. The walls of the air-vesicles, and coats of the blood-vessels, are similar, in their mechanical arrangement, to the membranous bladder in the before described experiment. As the oxygen of the air has greater affinity for blood than for nitrogen, so it permeates the membranes that intervene between the air and blood more readily than the nitrogen. As the carbonic acid and water have a greater affinity for air than for the other elements of the blood, so they will also pass through the walls of the blood-vessels and air-cells more readily than the other elements of the dark-colored blood.
Fig. 98.
Fig. 98. 1, A bronchial tube divided into three branches. 2, 2, 2, Air-cells. 3, Branches of the pulmonary artery, that spread over the air-cells. Through the pulmonary artery the dark, impure blood is carried to the air-cells of the lungs. 4, Branches of the pulmonary vein, that commence at the minute terminations of the pulmonary artery. Through the pulmonary vein the red blood is returned to the heart.
492. As the impure blood is passing in the minute vessels over the air-cells, the oxygen passes through the thin coats of the air-cells and blood-vessels, and unites with the blood. At the same time, the carbonic acid and water leave the blood, and pass through the coats of the blood-vessels and air-cells, and mix with the air in the cells. These are thrown out of the system every time we breathe. This interchange of products produces the change in the color of the blood.
Explain fig. 98. 492. How and where is the blood changed?
Experiment. Fill a bladder with dark blood drawn from any animal. Tie the bladder closely, and suspend it in the air. In a few hours, the blood next to the membrane will have become of a bright red color. This is owing to the oxygen from the air passing through the bladder, and uniting with the blood, while the carbonic acid has escaped through the membrane.
Fig. 99.
Fig. 99. An ideal view of the pulmonary circulation. 1, 1, The right lung. 2, 2, The left lung. 3, The trachea. 4, The right bronchial tube. 5, The left bronchial tube. 6, 6, 6, 6, Air-cells. 7, The right auricle. 8, The right ventricle. 9, The tricuspid valves. 10, The pulmonary artery. 11, The branch to the right lung. 12, The branch to the left lung. 13, The right pulmonary vein. 14, The left pulmonary vein. 15, The left auricle. 16, The left ventricle. 17, The mitral valves.
493. The presence of carbonic acid and watery vapor in the expired air, can be proved by the following experiments: 227 1st. Breathe into lime-water, and in a few minutes it will become of a milk-white color. This is owing to the carbonic acid of the breath uniting with the lime, forming the carbonate of lime. 2d. Breathe upon a cold, dry mirror for a few minutes, and it will be covered with moisture. This is condensed vapor from the lungs. In warm weather, this watery vapor is invisible in the expired air, but in a cold, dry morning in winter, the successive jets of vapor issuing from the mouth and nose are sufficiently obvious.
Give the experiment showing that oxygen changes the dark-colored blood to a bright red color. What is represented by fig. 99? 493. How can the presence of carbonic acid in the lungs be proved?
494. From the lungs are eliminated other impurities beside carbonic acid, the perceptible quality of which is various in different persons. The offensive breath of many persons may be caused by decayed teeth, or the particles of food that may be retained between them, but it often proceeds from the secretion, in the lungs, of certain substances which previously existed in the system.
Illustration. When spirituous liquors are taken into the stomach, they are absorbed by the veins and mixed with the dark-colored blood, in which they are carried to the lungs to be expelled from the body. This will explain the fact, which is familiar to most persons, that the odor of different substances is perceptible in the breath, or expired air, long after the mouth is free from these substances.
How the watery vapor? 494. Are there other excretions from the lungs? Give the illustration.
Note. Let the anatomy and physiology of the respiratory organs be reviewed from figs. 96, 97, and 99, or from anatomical outline plates Nos. 5 and 7.
495. For man to enjoy the highest degree of health, it is necessary that the impure “venous” blood be properly changed. As this is effected in the lungs by the action of the air, it follows that this element, when breathed, should be pure, or contain twenty-one per cent. of oxygen to about seventy-nine per cent. of nitrogen.
496. The volume of air expelled from the lungs is somewhat less than that which is inspired. The amount of loss varies under different circumstances. An eightieth part of the volume taken into the lungs, or half a cubic inch, may be considered an average estimate.
497. The quality and purity of the air is affected by every respiration. 1st. The quantity of oxygen is diminished. 2d. The amount of carbonic acid is increased. 3d. A certain proportion of watery vapor is ejected from the lungs in the expired air. Of the twenty-one parts of oxygen in the inspired air, only eighteen parts are expired, while the carbonic acid and watery vapor are increased about four per cent. The quantity of nitrogen is nearly the same in the expired as in the inspired air.
Observation. It is now fully ascertained that while the chemical composition of the blood is essentially changed, its 229 weight remains the same, as the carbon and hydrogen discharged are equal to the united weight of the oxygen and nitrogen absorbed.
495–546. Give the hygiene of the respiratory organs. 495. What is necessary that man enjoy the highest degree of health? 496. How does the volume Of expired air compare with that which was inspired? Does this loss vary, and what is an average estimate? 497. How is the purity of the air affected by respiration? How is the inhaled oxygen affected? What effect on the carbonic acid and watery vapor? On the nitrogen? What is said respecting the weight of the blood?
498. If one fourth part of the volume of air received by the lungs at one inspiration is decomposed at one “beat” of the heart, it might be supposed that if the expired air be again received into the lungs, one half of the oxygen would be consumed, and, in a similar ratio, if re-breathed four times, all the oxygen would be consumed. But it does not follow, if the air is thus re-breathed, that the same changes will be effected in the lungs. For air that has been inspired does not part with its remaining oxygen as freely as when it contains the proper amount of this life-giving element, and thus the changes in the impure blood are not so completely effected.
Illustration. In the process of dyeing, each successive article immersed in the dye weakens it; but it does not follow that the dye each time is affected in the same degree, or that the coloring matter by repeated immersions can be wholly extracted. The same principle applies to the exchange of oxygen and carbonic acid gas in the lungs.
499. If the inspired air is free from moisture and carbonic acid, these substances contained in the blood will be more readily imparted to it. When the air is loaded with vapor, they are removed more slowly; but if it is saturated with moisture, no vapor will escape from the blood through the agency of the lungs. This may be illustrated by the following experiment: Take two and a half pounds of water, add to it half a pound of common salt, (chloride of sodium,) and it will readily mix with the water; and to this solution add the same quantity of salt, and it will be dissolved more slowly. Again, add more salt, and it will remain undissolved, as the water has become saturated by the pound before dissolved.
498. Does air that is re-breathed freely impart its oxygen? Why? 499. What is the effect on the blood when the air is free from vapor and carbonic acid? When loaded with vapor? When saturated? How is this illustrated?
500. The principle in this experiment is analogous to that of the union between carbonic gas and atmospheric air. Allen and Pepy showed by experiment, that air which had been once breathed, contained eight and a half per cent. of carbonic acid. They likewise showed, that no continuance of the respiration of the same air could make it take up more than ten per cent. This is the point of saturation.
Experiment. Sink a glass jar that has a stop-cock, or one with a glass stopper, into a pail of water, until the air is expelled from the jar. Fill the lungs with air, and retain it in the chest a short time, and then breathe into the jar, and instantly close the stop-cock. Close the opening of the jar that is under the water with a piece of paper laid on a plate of sufficient size to cover the opening, invert the jar, and sink into it a lighted candle. The flame will be extinguished as quickly as if put in water.[15] Remove the carbonic acid by inverting the jar, and place a lighted candle in it, and the flame will be as clear as when out of the jar.
Observations. 1st. It is familiarly known that a taper will not burn where carbonic acid exists in any considerable quantity, or when there is a marked deficiency of oxygen. From this originated the judicious practice of sinking a lighted candle into a well or pit before descending into it. If the flame is extinguished, respiration cannot there be maintained, and life would be sacrificed should a person venture in, until the noxious air is removed.
500. What did the experiments of Allen and Pepy show? How can the presence of carbonic gas in the expired air be demonstrated? State observation 1st. Observation 2d.
2d. It is the action of carbonic acid upon the respiratory 231 organs, that gives rise to a phenomenon frequently seen in mines and caves. A man may enter these subterranean rooms, and feel no inconvenience in breathing; but the dog that follows him, falls apparently dead, and soon dies if not speedily removed to pure air. This arises from the fact that this gas is heavier than air, and sinks to the bottom of the room or cave.
3d. While it is true that carbonic acid possesses properties that render it unfit to be breathed, it is, notwithstanding, productive of very agreeable effects, when conveyed into the stomach. It forms the sparkling property of mineral waters, and fills the bubbles that rise when beer or cider is fermenting.
501. Pure atmospheric air is best adapted to a healthy action of the system. As the air cannot be maintained pure under all circumstances, the question may be asked, To what degree may the air be vitiated and still sustain life? and what is the smallest quantity of pure air a person needs each minute to maintain good health? Birnan says, that air which contains more than three and a half per cent. of carbonic acid is unfit for respiration, and, as air once respired contains eight and a half per cent. of carbonic acid, it clearly shows that it is not fitted to be breathed again.
502. No physiologist pretends that less than seven cubic feet of air are adequate for a man to breathe each minute, while Dr. Reid allows ten feet. The necessity of fifteen or twenty times the amount of air actually taken into the lungs, arises from the circumstance, that the expired air mixes with and vitiates the surrounding element that has not been inhaled.
503. The quantity of air which different persons actually 232 need, varies. The demand is modified by the size, age, habits, and condition of the body. A person of great size who has a large quantity of blood, requires more air than a small man with a less amount of circulating fluid. Individuals whose labor is active, require more air than sedentary or idle persons, because the waste of the system is greater. On the same principle, the gormandizer needs more of this element than the person of abstemious habits. So does the growing lad require more air than an adult of the same weight, for the reason that he consumes more food than a person of mature years. Habit also exerts a controlling influence. A man who works in the open air suffers more when placed in a small, unventilated room, than one who is accustomed to breathe the confined air of workshops.
Observation 3d. 501. What questions may be asked respecting the inspired air? Give the remark of Birnan. 502. How many cubic feet of air are adequate for a man to breathe each minute? How much does Dr. Reid allow? 503. Mention some reasons why different persons do not require the same amount of air.
504. Air, in which lamps will not burn with brilliancy, is unfitted for respiration. In crowded rooms, which are not ventilated, the air is vitiated, not only by the abstraction of oxygen and the deposition of carbonic acid, but by the excretions from the skin and lungs of the audience. The lamps, under such circumstances, emit but a feeble light. Let the oxygen gas be more and more expended, and the lamps will burn more and more feebly, until they are extinguished.
Illustrations. 1st. The effects of breathing the same air again and again, are well illustrated by an incident that occurred in one of our halls of learning. A large audience had assembled in an ill-ventilated room, to listen to a lecture; soon the lamps burned so dimly that the speaker and audience were nearly enveloped in darkness. The oppression, dizziness, and faintness experienced by many of the audience induced them to leave, and in a few minutes after, the lamps were observed to rekindle, owing to the exchange of pure air on opening the door.
How is it with the laborer? With the gormandizer? With the person that works in the open air? 504. What effect has impure air on a burning lamp? Give the illustration of the effects of impure air on lighted lamps.
2d. In the “Black Hole of Calcutta,” one hundred and forty-six Englishmen were shut up in a room eighteen feet square, with only two small windows on the same side to admit air. On opening this dungeon, ten hours after their imprisonment, only twenty-three were alive. The others had died from breathing impure air.
505. Air that has become impure from the abstraction of oxygen, an excess of carbonic acid, or the excretions from the lungs and skin, has a deleterious effect on the body. When this element is vitiated from the preceding causes, it prevents the proper arterialization, or change in the blood. For this reason, pure air should be admitted freely and constantly into work-shops and dwelling-houses, and the vitiated air permitted to escape. This is of greater importance than the warming of these apartments. We can compensate for the deficiency of a stove, by an extra garment or an increased quantity of food; but neither garment, exercise, nor food will compensate for pure air.
506. School-rooms should be ventilated. If they are not, the pupils will be restless, and complain of languor and headache. Those unpleasant sensations are caused by a want of pure air, to give an adequate supply of oxygen to the lungs. When pupils breathe for a series of years such vitiated air, their life is undoubtedly shortened, by giving rise to consumption and other fatal diseases.
Illustration. A school-room thirty feet square and eight feet high, contains 7200 cubic feet of air. This room will seat sixty pupils, and, allowing ten cubic feet of air to each pupil per minute, all the air in the room will be vitiated in twelve minutes.
Observation. In all school-rooms where there is not adequate 234 ventilation, it is advisable to have a recess of five or ten minutes each hour. During this time, let the pupils breathe fresh air, and open the doors and windows, so that the air of the room shall be completely changed.
Of the effects of breathing impure air. 505. In preserving health, what is of greater importance than warming the room? 506. Why should a school-room be ventilated? Give the illustration.
507. Churches, concert halls, and all rooms designed for a collection of individuals, should be amply ventilated. While the architect and workmen are assiduous in giving these public rooms architectural beauty and splendor, by adorning the ceiling with Gothic tracery, rearing richly carved columns, and providing carefully for the warming of the room, it too frequently happens that no direct provision is made for the change of that element which gives us beauty, strength, and life.
Illustration. A hall sixty feet by forty, and fifteen feet high, contains 36,000 cubic feet of air. A hall of this size will seat four hundred persons; by allowing ten cubic feet of air to each person per minute, the air of the room will be rendered unfit for respiration in nine minutes.
508. Railroad cars, cabins of steam and canal-boats, omnibuses, and stage-coaches, require ample ventilation. In the construction of these public conveyances, too frequently, the only apparent design is, to seat the greatest number of persons, regardless of the quantity and character of the air to maintain health and even life. The character of the air is only realized when, from the fresh, pure air, we enter a crowded cabin of a boat or a closed coach; then the vitiated air from animal excretions and noxious gases is offensive, and frequently produces sickness.
509. The influence of habit is strikingly expressed by Birnan, in the “Art of Warming and Ventilating Rooms:” “Not the least remarkable example of the power of habit is 235 its reconciling us to practices which, but for its influence, would be considered noxious and disgusting. We instinctively shun approach to the dirty, the squalid, and the diseased, and use no garment that may have been worn by another. We open sewers for matters that offend the sight or the smell, and contaminate the air. We carefully remove impurities from what we eat and drink, filter turbid water, and fastidiously avoid drinking from a cup that may have been pressed to the lips of a friend. On the other hand, we resort to places of assembly, and draw into our mouths air loaded with effluvia from the lungs, skin, and clothing of every individual in the promiscuous crowd—exhalations offensive, to a certain extent, from the most healthy individuals; but when arising from a living mass of skin and lungs, in all stages of evaporation, disease, and putridity,—prevented by the walls and ceiling from escaping—they are, when thus concentrated, in the highest degree deleterious and loathsome.”
What suggestion when a school-room is not ventilated? 507. What is said in regard to ventilating churches, concert halls, &c.? State the illustration. 508. What remarks relative to public conveyances? 509. State the influence of habit by Birnan.
510. The sleeping-room should be so ventilated that the air in the morning will be as pure as when retiring to rest in the evening. Ventilation of the room would prevent morning headaches, the want of appetite, and languor—so common among the feeble. The impure air of sleeping-rooms probably causes more deaths than intemperance. Look around the country, and those who are most exposed, who live in huts but little superior to the sheds that shelter the farmer’s flocks, are found to be the most healthy and robust. Headaches, liver complaints, coughs, and a multitude of nervous affections, are almost unknown to them; not so with those who spend their days and nights in rooms in which the sashes of the windows are calked, or perchance doubled, to prevent the keen but healthy air of winter from entering their apartments. Disease and suffering are their constant companions.
510. What is said of the ventilation of sleeping-rooms? What would adequate ventilation prevent? Give a common observation.
Illustration. By many, sleeping apartments twelve feet square and seven feet high, are considered spacious for two persons, and good accommodations for four to lodge in. An apartment of this size contains 1008 cubic feet of air. Allowing ten cubic feet to each person per minute, two occupants would vitiate the air of the room in fifty minutes, and four in twenty-five minutes. When lodging-rooms are not ventilated, we would strongly recommend early rising.
511. The sick-room, particularly, should be so arranged that the impure air may escape, and pure air be constantly admitted into the room. It is no unusual practice in some communities, when a child or an adult is sick of an acute disease, to prevent the ingress of pure air, simply from the apprehension of the attendants, that the patient will contract a cold. Again, the prevalent custom of several individuals sitting in the sick-room, particularly when they remain there for several hours, tends to vitiate the air, and, consequently, to increase the suffering and danger of the sick person. In fevers or inflammatory diseases of any kind, let the patient breathe pure air; for the purer the blood, the greater the power of the system to remove disease, and the less the liability to contract colds.
Observation. Among children, convulsions, or “fits,” usually occur when they are sleeping. In many instances, these are produced by the impure air which is breathed. To prevent these alarming and distressing convulsions, the sleeping-room should be ventilated, and there should be no curtains around the bed, or coverings over the face, as they produce an effect similar to that experienced when sleeping in a small, unventilated room. To relieve a child when convulsed, carry it into the open air.
What is said of the size of sleeping-rooms? 511. What is said of the sick-room? Mention some prevailing customs in reference to these rooms. What is said of convulsions among children?
512. While occupying a room, we are insensible of the 237 gradual vitiation of the air. This is the result of the diminished sensibility of the nervous system, and gradual adaptation of the organs to blood of a less stimulating character. This condition is well illustrated in the hibernating animals. We are insensible of the impure air of unventilated sleeping-rooms, until we leave them for a walk or ride. If they have been closed, we are made sensible of the character of the air as soon as we reënter them, for the system has regained its usual sensibility while inhaling a purer atmosphere.
513. In the construction of every inhabited room, there should be adequate means of ventilation, as well as warming. No room is well ventilated, unless as much pure air is brought into it as the occupants vitiate at every respiration. This can be effected by making an aperture in the ceiling of the room, or by constructing a ventilating flue in the chimney. This should be in contact with the flues for the escape of smoke, but separated from them by a thin brick partition. The hot air in the smoke flues will warm the separating brick partition, and consequently rarefy the air in the ventilating flue. Communication from every room in a house should be had to such flues. The draught of air can be regulated by well-adjusted registers, which in large rooms should be placed near the floor as well as near the ceiling.
514. While provision is made for the escape of rarefied impure air, we should also provide means by which pure air may be constantly admitted into the room, as the crevices of the doors and windows are not always sufficient; and, if they should be adequate, air can be introduced in a more convenient, economical, and appropriate manner. There should be an aperture opposite the ventilating flue, at or near the floor, to connect with the outer walls of the building or external air. 238 But if pure heated air is introduced into the room, it obviates the necessity of the introduction of the external air.[16]
512. Why are we insensible to the gradual vitiation of the air of an unventilated room? 513. What is very important in the building of every inhabited room? How can a room be well ventilated? 514. What is said relative to a communication with the external air?
515. In warming rooms, the hot air furnaces, or box and air-tight stoves converted into hot air furnaces, should be used in preference to the ordinary stoves. The air thus introduced into the room is pure as well as warm. In the adaptation of furnaces to dwelling-houses, &c., it is necessary that the air should pass over an ample surface of iron moderately heated; as a red heat abstracts the oxygen from the contiguous air, and thus renders it unfit to be respired.[17]
Observation. Domestic animals need a supply of pure air as well as man. The cows of cities, that breathe a vitiated air, have, very generally, tubercles. Sheep that are shut in a confined air, die of a disease called the “rot,” which is of a tuberculous character. Interest and humanity require that the buildings for animals be properly ventilated.
515. How should rooms be warmed? What is necessary in the adaptation of furnaces to dwelling-houses?
516. The change that is effected in the blood while passing through the lungs, not only depends upon the purity of the air, but the amount inspired. The quantity varies according to the size of the chest, and the movement of the ribs and diaphragm.
517. The size of the chest and lungs can be reduced by moderate and continued pressure. This is most easily done in infancy, when the cartilages and ribs are very pliant; yet it can be effected at more advanced periods of life, even after the chest is fully developed. For want of knowledge of the pliant character of the cartilages and ribs in infants, too many mothers, unintentionally, contract their chests, and thus sow the seeds of disease by the close dressing of their offspring.
518. If slight but steady pressure be continued from day to day and from week to week, the ribs will continue to yield more and more, and after the expiration of a few months, the chest will become diminished in size. This will be effected without any suffering of a marked character; but the general health and strength will be impaired. It is not the violent and ephemeral pressure, but the moderate and protracted, that produces the miscalled, “genteel,” contracted chests.
519. The style of dress which at the present day is almost universal, is a prolific cause of this deformity. These baneful 240 fashions are copied from the periodicals, so widely circulated, containing a “fashion plate of the latest fashions, from Paris.” In every instance; the contracted, deformed, and, as it is called, lady-like waist, is portrayed in all its fascinating loveliness. These periodicals are found on almost every centre-table, and exercise an influence almost omnipotent. If the plates which corrupt the morals are excluded by civil legislation, with the same propriety ought not those to be suppressed that have a tendency so adverse to health?
516. What varies the amount of air received into the lungs? 517. How can the size of the chest be diminished? When is this most easily effected? 518. How are the miscalled, “genteel,” contracted chests usually produced? 519. What is said of the style of the dress at the present day?
Fig. 100. A correct outline of the Venus de Medici, the beau ideal of female symmetry.
Fig. 101. An outline of a well-corseted modern beauty.
One has an artificial, insect waist; the other, a natural waist. One has sloping shoulders, while the shoulders of the other are comparatively elevated, square, and angular. The proportion of the corseted female below the waist, is also a departure from the symmetry of nature.
Observations. 1st. The Chinese, by compressing the feet of female children, prevent their growth; so that the foot of a 241 Chinese belle is not larger than the foot of an American girl of five years.
What does fig. 100 represent? Fig. 101? Give observation 1st.
2d. The American women compress their chests, to prevent their growth; so that the chest of an American belle is not larger than the chest of a Chinese girl of five years. Which country, in this respect, exhibits the greater intelligence?
3d. The chest can be deformed by making the linings of the waists of the dresses tight, as well as by corsets. Tight vests, upon the same principle, are also injurious.
520. In children, who have never worn close garments, the circumference of the chest is generally about equal to that of the body at the hips; and similar proportions would exist through life, if there were no improper pressure of the clothing. This is true of the laboring women of the Emerald Isle, and other countries of Europe, and in the Indian female, whose blanket allows the free expansion of the chest. The symmetrical statues of ancient sculptors bear little resemblance to the “beau ideal” of American notions of elegant form. This perverted taste is in opposition to the laws of nature. The design of the human chest is not simply to connect the upper and lower portions of the body, like some insects, but to form a case for the protection of the vital organs.
521. Individuals may have small chests from birth. This, to the particular individual, is natural; yet it is adverse to the great and general law of Nature relative to the size of the human chest. Like produces like, is a general law of the animal and vegetable kingdoms. No fact is better established, than that which proves the hereditary transmission 242 from parents to children of a constitutional liability to disease and the same may be said in regard to their conformations. If the mother has a small, taper waist, either hereditary or acquired, this form may be impressed on her offspring;—thus illustrating the truthfulness of scripture, “that the sins of the parents shall be visited upon the children unto the third and fourth generation.”
Observation 2d. Observation 3d. 520. What is the size of the chest of a child that has always worn loose clothing? What is said of the size of the laboring women of Ireland, and the Indian female? How is it in ancient statues? What is the design of the chest? 521. What is a general law of both the animal and vegetable kingdoms? What fact in this connection is well established?
522. The quantity of air inhaled is modified by the capacity of the respiratory organs. The necessity of voluminous lungs may he elucidated by the following experiment: Suppose a gill of alcohol, mixed with a gill of water, be put into a vessel having a square foot of surface, and over the vessel a membrane be tied, and that the water will evaporate in twenty-four hours. If the surface had been only six inches square, only one fourth of the water would have evaporated through the membrane in the given time. If the surface had been extended to two square feet, the water would have evaporated in twelve hours.
523. Apply this principle to the lungs: suppose there are two hundred feet of carbonic acid to be carried out of the system every twenty-four hours. This gas, in that time, will pass through a vesicular membrane of two thousand square feet. If the lungs were diminished in size, so that there would be only one thousand square feet of vesicular membrane, the amount of carbonic acid would not, and could not, be eliminated from the system. Under such circumstances, the blood would not be purified.
524. Again; suppose the two thousand square feet of membrane would transmit two hundred cubic feet of oxygen into the system every twenty-four hours. If it should be diminished one half, this amount of oxygen would not pass into the blood. From the above illustrations we may learn 243 the importance of well-developed chests and voluminous lungs; for, by increasing the size of the lungs, the oxygen is more abundantly supplied to the blood, and this fluid is more perfectly deprived of its carbon and hydrogen.
What does this hereditary transmission prove? 522. How is the necessity of voluminous lungs illustrated? 525. How is this principle applied to the interchange of products in the lungs?
525. The chest is not only most expanded at its lower part, but the portion of the lungs that occupies this space of the thoracic cavity contains the greater part of the air-cells; and, from the lower two thirds of the lungs the greatest amount of carbonic acid is abstracted from the blood, and the greatest amount of oxygen gas is conveyed into the circulating fluid. Hence, contracting the lower ribs is far more injurious to the health than diminishing the size of the upper part of the chest.
526. The question is often asked, Can the size of the chest and the volume of the lungs be increased, when they have been injudiciously compressed, or have inherited this unnatural form? The answer is in the affirmative. The means for attaining this end are, a judicious exercise of the lungs, by walking in the open air, reading aloud, singing, sitting erect, and fully inflating the lungs at each act of inspiration. If the exercise be properly managed and persevered in, it will expand the chest, and give tone and health to the important organs contained in it. But, if the exercise be ill-timed or carried to excess, the beneficial results sought will probably not be attained.
Observation. Scholars, and persons who sit much of the time, should frequently, during the day, breathe full and deep, so that the smallest air-cells may be fully filled with air. While exercising the lungs, the shoulders should be thrown back and the head held erect.
527. The movement of the ribs and diaphragm is modified by the dress. When the lungs are properly filled with air, 244 the chest is enlarged in every direction. If any article of apparel is worn so tight as to prevent the full expansion of the chest and abdomen, the lungs, in consequence, do not receive air sufficient to purify the blood. The effect of firm, unyielding clothing, when worn tight, in preventing a due supply of air to the lungs, may be shown by the following illustration.
525. Why is it more injurious to contract the lower part of the chest than the upper? 526. How can the size of the chest be increased when it is contracted? Give the observation. 527. How is the movement of the ribs and diaphragm modified?
Illustration. If the diameter of a circle is three feet, the circumference will be nine feet. If the diameter is extended to four feet, the circumference will be increased to twelve feet. Should a tight band be thrown around a circle of nine feet, its diameter cannot be increased, for the circumference cannot be enlarged.
528. Any inelastic band, drawn closely around the lower part of the chest, or the abdomen, below the ribs, operates like the band in the preceding illustration, in restricting the movement of the ribs. When any article of dress encircles either the chest or abdomen, so as to prevent an increase of its circumference, it has an injudicious tendency, as it prevents the introduction of air in sufficient quantities to purify the blood. The question is not, How much restriction of the respiratory movements can be endured, and life continue? but, Does any part of the apparel restrict the movements? If it does, it is a violation of the organic laws; and though Nature is profuse in her expenditures, yet sooner or later, she sums up her account.
529. In determining whether the apparel is worn too tight, inflate the lungs, and, if no pressure is felt, no injurious effects need be apprehended from this cause. In testing the tightness of the dress, some persons will contract to the utmost the abdominal muscles, and thus diminish the size of the 245 chest, by depressing the ribs; when this is done, the individual exclaims, “How loose my dress is!” This practice is both deceptive and ludicrous. A good test is, to put the hand on the chest below the arm; if there is no movement of the ribs during respiration, the apparel is too tight. The only reliable test, however, is a full inflation of the lungs.
How is the effect of unyielding clothing, when worn tight, illustrated? 528. What effect has an inelastic band upon the lower part of the chest? What question is asked? 529. How can we determine whether the apparel is worn too tight?
Observation. Many individuals do not realize the small amount of force that will prevent the enlargement of the chest. This can be demonstrated by drawing a piece of tape tightly around the lower part of the chest of a vigorous adult, and confining it with the thumb and finger. Then endeavor fully to inflate the lungs, and the movement of the ribs will be much restricted.
530. The position in standing and sitting influences the movement of the ribs and diaphragm. When the shoulders are thrown back, and when a person stands or sits erect, the diaphragm and ribs have more freedom of motion, and the abdominal muscles act more efficiently; thus the lungs have broader range of movement than when the shoulders incline forward, and the body is stooping.
531. Habit exercises an influence upon the range of the respiratory movements. A person who has been habituated to dress loosely, and whose inspirations are full and free, suffers more from the tightness of a vest or waistband, than one, the range of movements of whose chest has long been subjected to tight lacing.
532. The condition of the brain exercises a great influence upon respiration. If the brain is diseased, or the mind depressed by grief, tormented by anxiety, or absorbed by abstract thought, the contractile energy of the diaphragm and 246 muscles that elevate the ribs, is much diminished, and the lungs are not so fully inflated, as when the mind is influenced by joy or other exhilarating emotions. The depressing passions likewise lessen the frequency of respiration. By the influence of these causes, the blood is but partially purified, and the whole system becomes enfeebled. Here we may see the admirable harmony between the different parts of the body, and the adaptation of all the functions to each other.
Give another test. How can the amount of pressure necessary to prevent the enlargement of the chest be demonstrated? 530. Show the effect of position on the movements of the ribs and diaphragm. 531. Show the effect of habit on the respiratory movements. 532. State the influence of the mind upon respiration.
533. As the quantity of air inhaled at each unimpeded inspiration in lungs of ample size, is about forty cubic inches, it follows, if the movement of the ribs and diaphragm is restricted by an enfeebled action of the respiratory muscles, or by any other means, the blood will not be perfectly purified. In the experiment, (§ 522, 523,) suppose forty cubic inches of air must pass over the membrane twenty times every minute, and that this is the amount required to remove the vapor which arises from the membrane; if only half of this amount of air be supplied each minute, only one half as much water will be removed from the alcohol through the membrane in twenty-four hours; consequently, the alcohol would be impure from the water not being entirely removed.
534. Restrain the elevation of the ribs and depression of the diaphragm, so that the quantity of air conveyed into the lungs will be reduced to twenty cubic inches, when forty are needed, and the results will be as follows: Only one half of the carbonic acid will be eliminated from the system, and the blood will receive but one half as much oxygen as it requires. This fluid will then be imperfectly oxydated, and partially freed of its impurities. The impure blood will be returned to the left side of the heart, and the whole system will suffer from an infringement of organic laws.
533. Illustrate the effect upon the blood when the respiratory muscles are enfeebled in their action. 534. Show how the blood is imperfectly purified by restricting the movements of the ribs and diaphragm.