XXII. RESPIRATION AND EXCRETION
Problems.—A study of respiration to find out:—
(a) What changes in blood and air take place within the lungs.
(b) The mechanics of respiration.
A study of ventilation to discover:—
(a) The reason for ventilation.
(b) The best method of ventilation.
A study of the organs of excretion.
Laboratory Suggestions
Demonstration.—Comparison of lungs of frog with those of bird or mammal.
Experiment.—The changes of blood within the lungs.
Experiment.—Changes taking place in air in the lungs.
Experiment.—The use of the ribs in respiration.
Demonstration experiment.—What causes the filling of air sacs of the lungs?
Demonstration experiment.—What are the best methods of ventilating a room?
Demonstration.—Best methods of dusting and cleaning.
Demonstration.—Beef or sheep's kidney to show areas.
Necessity for Respiration.—We have seen that plants and animals need oxygen in order that the life processes may go on. Food is oxidized to release energy, just as coal is burned to give heat to run an engine. As a draft of air is required to make fire under the boiler, so, in the human body, oxygen must be given so that food in tissues may be oxidized to release energy used in work. This oxidation takes place in the cells of the body, be they part of a muscle, a gland, or the brain. Blood, in its circulation to all parts of the body, is the medium which conveys the oxygen to that place in the body where it will be used.
Air passages in the human lungs. a, larynx; b, trachea (or windpipe); c, d, bronchi; e, bronchial tubes; f, cluster of air cells.
The Organs of Respiration in Man.—We have alluded to the fact that the lungs are the organs which give oxygen to the blood and take from it carbon dioxide. The course of the air passing to the lungs in man is much the same as in the frog. Air passes through the nose, and into the windpipe. This cartilaginous tube, the top of which may easily be felt as the Adam's apple of the throat, divides into two bronchi. The bronchi within the lungs break up into a great number of smaller tubes, the bronchial tubes, which divide somewhat like the small branches of a tree. The bronchial tubes, indeed all the air passages, are lined with ciliated cells. The cilia of these cells are constantly in motion, beating with a quick stroke toward the outer end of the tube, that is, toward the mouth. Hence any foreign material will be raised from the throat first by the action of the cilia and then by coughing or "clearing the throat." The bronchi end in very minute air sacs, little pouches having elastic walls, into which air is taken when we inspire, or take a deep breath. In the walls of these pouches are numerous capillaries, the ends of arteries which pass from the heart into the lung. It is through the very thin walls of the air sacs that an interchange of gases takes place which results in the blood giving up part of its load of carbon dioxide, and taking up oxygen in its place. This exchange appears to be aided by the presence of an enzyme in the lung tissues. This is another example of the various kinds of work done by the enzymes of the body.
Diagram to show what the blood loses and gains in one of the air sacs of the lungs.
Changes in the Blood within the Lungs.—Blood, after leaving the lungs, is much brighter red than just before entering them. The change in color is due to a taking up of oxygen by the hæmoglobin of the red corpuscles. Changes taking place in blood are obviously the reverse of those which take place in air in the lungs. Every hundred cubic centimeters of blood going into the lungs contains 8 to 12 c.c. of oxygen, 45 to 50 c.c. of carbon dioxide, and 1 to 2 c.c. of nitrogen. The same amount of blood passing out of the lungs contains 20 c.c. of oxygen, 38 c.c. of carbon dioxide, and 1 to 2 c.c. of nitrogen. The water, of which about half a pint is given off daily, is mostly lost from the blood.
Changes in Air in the Lungs.—Air is much warmer after leaving the lungs than before it enters them. Breathe on the bulb of a thermometer to prove this. Expired air contains a considerable amount of moisture, as may be proved by breathing on a cold polished surface. This it has taken up in the air sacs of the lungs. The presence of carbon dioxide in expired air may easily be detected by the limewater test. Air such as we breathe out of doors contains, by volume:—
| Nitrogen | 76.95 |
| Oxygen | 20.61 |
| Carbon dioxide | .03 |
| Argon | 1.00 |
| Water vapor (average) | 1.40 |
| Air expired from the lungs contains:— | |
| Nitrogen | 76.95 |
| Oxygen | 15.67 |
| Carbon dioxide | 4.38 |
| Water vapor | 2.00 |
| Argon | 1.00 |
In other words, there is a loss between 4 and 5 per cent oxygen, and nearly a corresponding gain in carbon dioxide, in expired air. There are also some other organic substances present.
The respiration of cells.
Cell Respiration.—It has been shown, in the case of very simple animals, such as the amœba, that when oxidation takes place in a cell, work results from this oxidation. The oxygen taken into the lungs is not used there, but is carried by the blood to such parts of the body as need oxygen to oxidize food materials in the cells. Since work is done in the cells of the body, food and oxygen are therefore required. The quantity of oxygen used by the body is nearly dependent on the amount of work performed. Oxygen is constantly taken from the blood by tissues in a state of rest and is used up when the body is at work. This is suggested by the fact that in a given time a man, when working, gives off more oxygen (in carbon dioxide) than he takes in during that time.
While work is being done certain wastes are formed in the cell. Carbon dioxide is given off when carbon is burned. But when proteins are burned, another waste product containing nitrogen is formed. This must be passed off from the cells, as it is a poison. Here again the lymph and blood, the common carriers, take the waste material to points where it may be excreted or passed out of the body.
The Mechanics of Respiration. The Pleura.—The lungs are covered with a thin elastic membrane, the pleura. This forms a bag in which the lungs are hung. Between the walls of the bag and the lungs is a space filled with lymph. By this means the lungs are prevented from rubbing against the walls of the chest.
The chest cavity (a) at the time of a full breath; (b), after an expiration. Explain how the cavity for lungs is made larger.
Breathing.—In every full breath there are two distinct movements, inspiration (taking air in) and expiration (forcing air out). In man an inspiration is produced by the contraction of the muscles between the ribs, together with the contraction of the diaphragm, the muscular wall just below the heart and lungs; this results in pulling down the diaphragm and pulling upward and outward of the ribs, thus making the space within the chest cavity larger. The lungs, which lie within this cavity, are filled by the air rushing into the larger space thus made. That this cavity is larger than it was at first may be demonstrated by a glance at the accompanying figure. An expiration is simpler than an inspiration, for it requires no muscular effort; the muscles relax, the breastbone and ribs sink into place, while the diaphragm returns to its original position.
Apparatus to show the mechanics of breathing.
A piece of apparatus which illustrates to a degree the mechanics of breathing may be made as follows: Attach a string to the middle of a piece of sheet rubber. Tie the rubber over the large end of a bell jar. Pass a glass Y-tube through a rubber stopper. Fasten two small toy balloons to the branches of the tube. Close the small end of the jar with the stopper. Adjust the tube so that the balloons shall hang free in the jar. If now the rubber sheet is pulled down by means of the string, the air pressure in the jar is reduced and the toy balloons within expand, owing to the air pressure down the tube. When the rubber is allowed to go back to its former position, the balloons collapse.
Diagram showing the relative amounts of tidal, complemental, reserve, and residual air. The brace shows the average lung capacity for the adult man.
Rate of Breathing and Amount of Air Breathed.—During quiet breathing, the rate of inspiration is from fifteen to eighteen times per minute; this rate largely depends on the amount of physical work performed. About 30 cubic inches of air are taken in and expelled during the ordinary quiet respiration. The air so breathed is called tidal air. In a "long" breath, we take in about 100 cubic inches in addition to the tidal air. This is called complemental air. By means of a forced expiration, it is possible to expel from 75 to 100 cubic inches more than tidal air; this air is called reserve air. What remains in the lungs, amounting to about 100 cubic inches, is called the residual air. The value of deep breathing is seen by a glance at the diagram. It is only by this means that we clear the lungs of the reserve air with its accompanying load of carbon dioxide.
Respiration under Nervous Control.—The muscular movements which cause an inspiration are partly under the control of the will, but in part the movement is beyond our control. The nerve centers which govern inspiration are part of the sympathetic nervous system. Anything of an irritating nature in the trachea or larynx will cause a sudden expiration or cough. When a boy runs, the quickened respiration is due to the fact that oxygen is used up rapidly and a larger quantity of carbon dioxide is formed. The carbon dioxide in the blood stimulates the nervous center which has control of respiration to greater activity, and quickened inspiration follows.
Need of Ventilation.—During the course of a day the lungs lose to the surrounding air nearly two pounds of carbon dioxide. This means that about three fifths of a cubic foot is given off by each person during an hour. When we are confined for some time in a room, it becomes necessary to get rid of this carbon dioxide. This can be done only by means of proper ventilation. A considerable amount of moisture is given off from the body, and this moisture in a crowded room is responsible for much of the discomfort. The air becomes humid and uncomfortable. It has been found that by keeping the air in motion in such a room (as through the use of electric fans) much of this discomfort is obviated.
Three ways of ventilating a room. i, inlet for air; o, outlet for air. Which is the best method of ventilation? Explain.
The presence of impurities in the air of a room may easily be determined by its odor. The odor of a poorly ventilated room is due to organic impurities given off with the carbon dioxide. This, fortunately, gives us an index of the amount of waste material in the air. Among the factors which take oxygen from the air in a closed room and produce carbon dioxide are burning gas or oil lamps and stoves, and the presence of a number of people.
Proper Ventilation.—Ventilation consists in the removal of air that has been used, and the introduction of a fresh supply to take its place. Heated air rises, carrying with it much of the carbon dioxide and other impurities. A good method of ventilation for the home is to place a board two or three inches high between the lower sash and the frame of a window or to have the window open an inch or so at the top and the bottom. An open fireplace in a room aids in ventilation because of the constant draft up the flue.
Sweeping and Dusting.—It is very easy to demonstrate the amount of dust in the air by following the course of a beam of light in a darkened room. We have already proved that spores of mold and yeast exist in the air. That bacteria are also present can be proved by exposing a sterilized gelatin plate to the air in a schoolroom for a few moments.[47]
Plate culture exposed for five minutes in a school hall where pupils were passing to recitations. Each spot is a colony of bacteria or mold.
Many of the bacteria present in the air are active in causing diseases of the respiratory tract, such as diphtheria, membranous croup, and tuberculosis. Other diseases, as colds, bronchitis (inflammation of the bronchial tubes), and pneumonia (inflammation of the tiny air sacs of the lungs), are also caused by bacteria.
Dust, with its load of bacteria, will settle on any horizontal surface in a room not used for three or four hours. Dusting and sweeping should always be done with a damp cloth or broom, otherwise the bacteria are simply stirred up and sent into the air again. The proper watering of streets before they are swept is also an important factor in health. Much dust is composed largely of dried excreta of animals. Soft-coal smoke does its share to add to the impurities of the air, while sewer gas and illuminating gas are frequently found in sufficient quantities to poison people. Pure air is, as can be seen, almost an impossibility in a great city.
A sleeping porch, an ideal way to get fresh air at night.
How to get Fresh Air.—As we know, green plants give off in the sunlight considerable more oxygen than they use, and they use up carbon dioxide. The air in the country is naturally purer than in the city, as smoke and bacteria are not so prevalent there, and the plants in abundance give off oxygen. In the city the night air is purer than day air, because the factories have stopped work, the dust has settled, and fewer people are on the streets. The old myth of "night air" being injurious has long since been exploded, and thousands of people of delicate health, especially those who have weak throat or lungs, are regaining health by sleeping out of doors or with the windows wide open. The only essential in sleeping out of doors or in a room with a low temperature is that the body be kept warm and the head be protected from strong drafts by a nightcap or hood. Proper ventilation at all times is one of the greatest factors in good health.
Change of Air.—Persons in poor health, especially those having tuberculosis, are often cured by a change of air. This is not always so much due to the composition of the air as to change of occupation, rest, and good food. Mountain air is dry, and relatively free from dust and bacteria, and often helps a person having tuberculosis. Air at the seaside is beneficial for some forms of disease, especially hay fever and bone tuberculosis. Many sanitariums have been established for this latter disease near the ocean, and thousands of lives are being annually saved in this way.
Unfavorable sleeping conditions. Explain why unfavorable.
Ventilation of Sleeping Rooms.—Sleeping in close rooms is the cause of much illness. Beds ought to be placed so that a constant supply of fresh air is given without a direct draft. This may often be managed with the use of screens. Bedroom windows should be thrown open in the morning to allow free entrance of the sun and air, bedclothes should be washed frequently, and sheets and pillow covers often changed. Bedroom furniture should be simple, and but little drapery allowed in the room.
Hygienic Habits of Breathing.—Every one ought to accustom himself upon going into the open air to inspire slowly and deeply to the full capacity of the lungs. A slow expiration should follow. Take care to force the air out. Breathe through the nose, thus warming the air you inspire before it enters the lungs and chills the blood. Repeat this exercise several times every day. You will thus prevent certain of the air sacs which are not often used from becoming hardened and permanently closed.
Relation of Proper Exercise to Health.—We are all aware that exercise in moderation has a beneficial effect upon the human organism. The pale face, drooping shoulders, and narrow chest of the boy or girl who takes no regular exercise is too well known. Exercise, besides giving direct use of the muscles, increases the work of the heart and lungs, causing deeper breathing and giving the heart muscles increased work; it liberates heat and carbon dioxide from the tissues where the work is taking place, thus increasing the respiration of the tissues themselves, and aids mechanically in the removal of wastes from tissues. It is well known that exercise, when taken some little time after eating, has a very beneficial effect upon digestion. Exercise and especially games are of immense importance to the nervous system as a means of rest. The increasing number of playgrounds in this country is due to this acknowledged need of exercise, especially for growing children.
Proper exercise should be moderate and varied. Walking in itself is a valuable means of exercising certain muscles, so is bicycling, but neither is ideal as the only form to be used. Vary your exercise so as to bring different muscles into play, take exercise that will allow free breathing out of doors if possible, and the natural fatigue which follows will lead you to take the rest and sleep that every normal body requires.
Exercise should always be limited by fatigue, which brings with it fatigue poisons. This is nature's signal when to rest. If one's use of diet and air is proper, the fatigue point will be much further off than otherwise. One should learn to relax when not in activity. The habit produces rest, even between exertions very close together, and enables one to continue to repeat those exertions for a much longer time than otherwise. The habit of lying down when tired is a good one.
The Relation of Tight Clothing to Correct Breathing.—It is impossible to breathe correctly unless the clothing is worn loosely over the chest and abdomen. Tight corsets and tight belts prevent the walls of the chest and the abdomen from pushing outward and interfere with the drawing of air into the lungs. They may also result in permanent distortion of parts of the skeleton directly under the pressure. Other organs of the body cavity, as the stomach and intestines, may be forced downward, out of place, and in consequence cannot perform their work properly.
Suffocation and Artificial Respiration.—Suffocation results from the shutting off of the supply of oxygen from the lungs. It may be brought about by an obstruction in the windpipe, by a lack of oxygen in the air, by inhaling some other gas in quantity, or by drowning. A severe electric shock may paralyze the nervous centers which control respiration, thus causing a kind of suffocation. In the above cases, death often may be prevented by prompt recourse to artificial respiration. To accomplish this, place the patient on his back with the head lower than the body; grasp the arms near the elbows and draw them upward and outward until they are stretched above the head, on a line with the body. By this means the chest cavity is enlarged and an inspiration produced. To produce an expiration, carry the arms downward, and press them against the chest, thus forcing the air out of the lungs. This exercise, regularly repeated every few seconds, if necessary for hours, has been the source of saving many lives.
Common Diseases of the Nose and Throat.—Catarrh is a disease to which people with sensitive mucous membrane of the nose and throat are subject. It is indicated by the constant secretion of mucus from these membranes. Frequent spraying of the nose and throat with some mild antiseptic solutions is found helpful. Chronic catarrh should be attended to by a physician. Often we find children breathing entirely through the mouth, the nose being seemingly stopped up. When this goes on for some time the nose and throat should be examined by a physician for adenoids, or growths of soft masses of tissue which fill up the nose cavity, thus causing a shortage of the air supply for the body. Many a child, backward at school, thin and irritable, has been changed to a healthy, normal, bright scholar by the removal of adenoids. Sometimes the tonsils at the back of the mouth cavity may become enlarged, thus shutting off the air supply and causing the same trouble as we see in a case of adenoids. The simple removal of the obstacle by a doctor soon cures this condition. (See page [395].)
Organs of Excretion.—All the life processes which take place in a living thing result ultimately, in addition to giving off of carbon dioxide, in the formation of organic wastes within the body. The retention of these wastes which contain nitrogen, is harmful to animals. In man, the skin and kidneys remove this waste from the body, hence they are called the organs of excretion.
Longitudinal section through a kidney.
The Human Kidney.—The human kidney is about four inches long, two and one half inches wide, and one inch in thickness. Its color is dark red. If the structure of the medulla and cortex (see figure above) is examined under the compound microscope, you will find these regions to be composed of a vast number of tiny branched and twisted tubules. The outer end of each of these tubules opens into the pelvis, the space within the kidney; the inner end, in the cortex, forms a tiny closed sac. In each sac, the outer wall of the tube has grown inward and carried with it a very tiny artery. This artery breaks up into a mass of capillaries. These capillaries, in turn, unite to form a small vein as they leave the little sac. Each of these sacs with its contained blood vessels is called a glomerulus.
Diagram of kidney circulation, showing a glomerulus and tubule: a, artery bringing blood to part; b, capillary bringing blood to glomerulus; b', vessel continuing with blood to vein; c, vein; t, tubule; G, glomerulus.
Wastes given off by the Blood in the Kidney.—In the glomerulus the blood loses by osmosis, through the very thin walls of the capillaries, first, a considerable amount of water (amounting to nearly three pints daily); second, a nitrogenous waste material known as urea; third, salts and other waste organic substances, uric acid among them.
These waste products, together with the water containing them, are known as urine. The total amount of nitrogenous waste leaving the body each day is about twenty grams. It is passed through the ureter to the urinary bladder; from this reservoir it is passed out of the body, through a tube called the urethra. After the blood has passed through the glomeruli of the kidneys it is purer than in any other place in the body, because, before coming there, it lost a large part of its burden of carbon dioxide in the lungs. After leaving the kidney it has lost much of its nitrogenous waste. So dependent is the body upon the excretion of its poisonous material that, in cases where the kidneys do not do their work properly, death may ensue within a few hours.
Diagram of a section of the skin. (Highly magnified.)
Structure and Use of Sweat Glands.—If you examine the palm of your hand with a lens, you will notice the surface is thrown into little ridges. In these ridges may be found a large number of very tiny pits; these are the pores or openings of the sweat-secreting glands. From each opening a little tube penetrates deep within the epidermis; there, coiling around upon itself several times, it forms the sweat gland. Close around this coiled tube are found many capillaries. From the blood in these capillaries, cells lining the wall of the gland take water, and with it a little carbon dioxide, urea, and some salts (common salt among others). This forms the excretion known as sweat. The combined secretions from these glands amount normally to a little over a pint during twenty-four hours. At all times, a small amount of sweat is given off, but this is evaporated or is absorbed by the underwear; as this passes off unnoticed, it is called insensible perspiration. In hot weather or after hard manual labor the amount of perspiration is greatly increased.
Regulation of Heat of the Body.—The bodily temperature of a person engaged in manual labor will be found to be but little higher than the temperature of the same person at rest. We know from our previous experiments that heat is released. Muscles, nearly one half the weight of the body, release about five sixths of their energy as heat. At all times they are giving up some heat. How is it that the bodily temperature does not differ greatly at such times? The temperature of the body is largely regulated by means of the activity of the sweat glands. The blood carries much of the heat, liberated in the various parts of the body by the oxidation of food, to the surface of the body, where it is lost in the evaporation of sweat. In hot weather the blood vessels of the skin are dilated; in cold weather they are made smaller by the action of the nervous system. The blood thus loses water in the skin, the water evaporates, and we are cooled off. The object of increased perspiration, then, is to remove heat from the body. With a large amount of blood present in the skin, perspiration is increased; with a small amount, it is diminished. Hence, we have in the skin an automatic regulator of bodily temperature.
Sweat Glands under Nervous Control.—The sweat glands, like the other glands in the body, are under the control of the sympathetic nervous system. Frequently the nerves dilate the blood vessels of the skin, thus helping the sweat glands to secrete, by giving them more blood.
"Thus regulation is carried out by the nervous system determining, on the one hand, the loss by governing the supply of blood to the skin and the action of the sweat glands; and on the other, the production by diminishing or increasing the oxidation of the tissues."—Foster and Shore, Physiology.
Colds and Fevers.—The regulation of blood passing through the blood vessels is under control of the nervous system. If this mechanism is interfered with in any way, the sweat glands may not do their work, perspiration may be stopped, and the heat from oxidation held within the body. The body temperature goes up, and a fever results.
A, blood vessels in skin normal;
B, when congested.
If the blood vessels in the skin are suddenly cooled when full of blood, they contract and send the blood elsewhere. As a result a congestion or cold may follow. Colds are, in reality, a congestion of membranes lining certain parts of the body, as the nose, throat, windpipe, or lungs.
When suffering from a cold, it is therefore important not to chill the skin, as a full blood supply should be kept in it and so kept from the seat of the congestion. For this reason hot baths (which call the blood to the skin), the avoiding of drafts (which chill the skin), and warm clothing are useful factors in the care of colds.
Hygiene of the Skin.—The skin is of importance both as an organ of excretion and as a regulator of bodily temperature. The skin of the entire body should be bathed frequently so that this function of excretion may be properly performed. Pride in one's own appearance forbids a dirty skin. For those who can stand it, a cold sponge bath is best. Soap should be used daily on parts exposed to dirt. Exercise in the open air is important to all who desire a good complexion. The body should be kept at an even temperature by the use of proper underclothing. Wool, a poor conductor of heat, should be used in winter, and cotton, which allows of a free escape of heat, in summer.
Cuts, Bruises, and Burns.—In case the skin is badly broken, it is necessary to prevent the entrance and growth of bacteria. This may be done by washing the wound with weak antiseptic solutions such as 3 per cent carbolic acid, 3 per cent lysol, or peroxide of hydrogen (full strength). These solutions should be applied immediately. A burn or scald should be covered at once with a paste of baking soda, with olive oil, or with a mixture of limewater and linseed oil. These tend to lessen the pain by keeping out the air and reducing the inflammation.
Summary of Changes in Blood within the Body.—We have already seen that red corpuscles in the lungs lose part of their load of carbon dioxide that they have taken from the tissues, replacing it with oxygen. This is accompanied by a change of color from purple (in blood which is poor in oxygen) to that of bright red (in richly oxygenated blood). Other changes take place in other parts of the body. In the walls of the food tube, especially in the small intestine, the blood receives its load of fluid food. In the muscles and other working tissues the blood gives up food and oxygen, receiving carbon dioxide and organic waste in return. In the liver, the blood gives up its sugar, and the worn-out red corpuscles which break down are removed (as they are in the spleen) from the circulation. In glands, it gives up materials used by the gland cells in their manufacture of secretions. In the kidneys, it loses water and nitrogenous wastes (urea). In the skin, it also loses some waste materials, salts, and water.
"The Effect of Alcohol on Body Heat.—It is usually believed that 'taking a drink' when cold makes one warmer. But such is not the case. In reality alcohol lowers the temperature of the body by dilating the blood vessels of the skin. It does this by means of its influence on the nervous system. It is, therefore, a mistake to drink alcoholic beverages when one is extremely cold, because by means of this more bodily heat is allowed to escape.
"Because alcohol is quickly oxidized, and because heat is produced in the process, it was long believed to be of value in maintaining the heat of the body. A different view now prevails as the result of much observation and experiment. Physiologists show by careful experiments that though the temperature of the body rises during digestion of food, it is lowered for some hours when alcohol is taken. The flush which is felt upon the skin after a drink of wine or spirits is due in part to an increase of heat in the body, but also to the paralyzing effect of the alcohol upon the capillary walls, allowing them to dilate, and so permitting more of the warm blood of the interior of the body to reach the surface. There it is cooled by radiation, and the general temperature is lowered."—Macy, Physiology.
Effect of Alcohol on Respiration.—Alcohol tends to congest the membrane of the throat and lungs. It does this by paralyzing the nerves which take care of the tiny blood vessels in the walls of the air tubes and air sacs. The capillaries become full of blood, the air spaces are lessened, and breathing is interfered with. The use of alcohol is believed by many physicians to predispose a person to tuberculosis. Certainly this disease attacks drinkers more readily than those who do not drink. Alcohol interferes with the respiration of the cells because it is oxidized very quickly within the body as it is quickly absorbed and sent to the cells. So rapid is this oxidation that it interferes with the oxidation of other substances. Using alcohol has been likened to burning kerosene in a stove; the operation is a dangerous one.
Effects of Tobacco on Respiration.—Tobacco smoke contains the same kind of poisons as the tobacco, with other irritating substances added. It is extremely irritating to the throat; it often causes a cough, and renders it more liable to inflammation. If the smoke is inhaled more deeply, the vaporized nicotine is still more readily absorbed and may thus produce greater irritation in the bronchi and lungs. Cigarettes are worse than other forms of tobacco, for they contain the same poisons with others in addition.
Effect of Alcohol on the Kidneys.—It is said that alcohol is one of the greatest causes of disease in the kidneys. The forms of disease known as "fatty degeneration of the kidney" and "Bright's disease" are both frequently due to this cause. The kidneys are the most important organs for the removal of nitrogenous waste.
Alcohol unites more easily with oxygen than most other food materials, hence it takes away oxygen that would otherwise be used in oxidizing these foods. Imperfect oxidation of foods causes the development and retention of poisons in the blood which it becomes the work of the kidneys to remove. If the kidneys become overworked, disease will occur. Such disease is likely to make itself felt as rheumatism or gout, both of which are believed to be due to waste products (poisons) in the blood.
Poisons produced by Alcohol.—When too little oxygen enters the draft of the stove, the wood is burned imperfectly, and there are clouds of smoke and irritating gases. So, if oxygen unites with the alcohol and too little reaches the cells, instead of carbon dioxide, water, and urea being formed, there are other products, some of which are exceedingly poisonous and which the kidneys handle with difficulty. The poisons retained in the circulation never fail to produce their poisonous effects, as shown by headaches, clouded brain, pain, and weakness of the body. The word "intoxication" means "in a state of poisoning." These poisons gradually accumulate as the alcohol takes oxygen from the cells. The worst effects come last, when the brain is too benumbed to judge fairly of their harm.
[47] Expose two sterilized dishes containing culture media; one in a room being swept with a damp broom, and the other in a room which is being swept in the usual manner. Note the formation of colonies of bacteria in each dish. In which dish does the more abundant growth take place?
Reference Books
elementary
Hunter, Laboratory Problems in Civic Biology. American Book Company.
Davison, Human Body and Health. American Book Company.
Gulick, Hygiene Series, Emergencies, Good Health. Ginn and Company.
Hough and Sedgwick, The Human Mechanism. Ginn and Company.
Macy, General Physiology. American Book Company.