Physiology and Hygiene for Secondary Schools. Francis M. Walters
are largely filled, at the same time, by the air which the last expiratory effort has left in the passages. By the action of currents and eddies and by the rapid diffusion of gas particles, the air from the outside mixes with that in the alveoli and comes in contact with the membranous walls. Here the oxygen, after being dissolved by the moisture in the membrane, diffuses into the blood. The carbon dioxide, on the other hand, being in excess in the blood, diffuses toward the air in the alveoli. The interchange of gases at the lungs, however, is not fully understood, and it is possible that other forces than osmosis play a part.
Fig. 43—Diagram illustrating lung capacity.
Capacity of the Lungs.—The air which passes into and from the lungs in ordinary breathing, called the tidal air, is but a small part of[pg 089] the whole amount of air which the lungs contain. Even after a forced expiration the lungs are almost half full; the air which remains is called the residual air. The air which is expelled from the lungs by a forced expiration, less the tidal air, is called the reserve, or supplemental, air. These several quantities are easily estimated. (See Practical Work.) In the average individual the total capacity of the lungs (with the chest in repose) is about one gallon. In forced inspirations this capacity may be increased about one third, the excess being known as the complemental air (Fig. 43).
Fig. 44—Diagram illustrating internal respiration and its dependence on external respiration. (Modified from Hall.) (See text.)
Internal, or Cell, Respiration.—The oxygen which enters the blood in the lungs leaves it in the tissues, passing through the lymph into the cells (Fig. 44). At the same time the carbon dioxide which is being formed at the cells passes into the blood. An exchange of gases is thus taking place between the cells and the blood, similar to[pg 090] that taking place between the blood and the air. This exchange is known as internal, or cell, respiration. By internal respiration the oxygen reaches the place where it is to serve its purpose, and the carbon dioxide begins its movement toward the exterior of the body. This "breathing by the cells" is, therefore, the final and essential act of respiration. Breathing by the lungs is simply the means by which the taking up of oxygen and the giving off of carbon dioxide by the cells is made possible.
HYGIENE OF RESPIRATORY ORGANS
The liability of the lungs to attacks from such dread diseases as consumption and pneumonia makes questions touching their hygiene of first importance. Consumption does not as a rule attack sound lung tissue, but usually has its beginning in some weak or enfeebled spot in the lungs which has lost its "power of resistance." Though consumption is not inherited, as some suppose, lung weaknesses may be transmitted from parents to children. This, together with the fact, now generally recognized, that consumption is contagious, accounts for the frequent appearance of this disease in the same family. Consumption as well as other respiratory affections can in the majority of cases be prevented, and in many cases cured, by an intelligent observation of well-known laws of health.
Breathe through the Nostrils.—Pure air and plenty of it is the main condition in the hygiene of the lungs. One necessary provision for obtaining pure air is that of breathing through the nostrils. Air is the carrier of dust particles and not infrequently of disease germs.33 Partly through[pg 091] the small hairs in the nose, but mainly through the moist membrane that lines the passages, the nostrils serve as filters for removing the minute solid particles (Fig. 45). While it is important that nose breathing be observed at all times, it is especially important when one is surrounded by a dusty or smoky atmosphere. Otherwise the small particles that are breathed in through the mouth may find a lodging place in the lungs.
Fig. 45—Human air filter. Diagram of a section through the nostrils; shows projecting bones covered with moist membrane against which the air is made to strike by the narrow passages. 1. Air passages. 2. Cavities in the bones. 3. Front lower portion of the cranial cavity.
In addition to removing dust particles and germs, other purposes are served by breathing through the nostrils. The warmth and moisture which the air receives in this way, prepare it for entering the lungs. Mouth breathing, on the other hand, looks bad and during sleep causes snoring. The habit of nose breathing should be established early in life.34
Cultivate Full Breathing.—Many people, while apparently taking in sufficient air to supply their need for oxygen, do not breathe deeply enough to "freely ventilate the lungs." "Shallow breathing," as this is called,[pg 092] is objectionable because it fails to keep up a healthy condition of the entire lung surface. Portions of the lungs to which air does not easily penetrate fail to get the fresh air and exercise which they need. As a consequence, they become weak and, by losing their "power of resistance," become points of attack in diseases of the lungs.35 The breathing of each individual should receive attention, and where from some cause it is not sufficiently full and deep, the means should be found for remedying the defect.
Causes of Shallow Breathing.—Anything that impedes the free movement of air into the lungs tends to cause shallow breathing A drooping of the back or shoulders and a curved condition of the spinal column, such as is caused by an improper position in sitting, interfere with the free movements of the ribs and are recognized causes. Clothing also may impede the respiratory movements and lead to shallow breathing. If too tight around the chest, clothing interferes with the elevation of the ribs; and if too tight around the waist, it prevents the depression of the diaphragm. Other causes of shallow breathing are found in the absence of vigorous exercise, in the leading of an indoor and inactive life, in obstructions in the nostrils and upper pharynx, and in the lack of attention to proper methods of breathing.
To prevent shallow breathing one should have the habit of sitting and standing erect. The clothing must not be allowed to interfere with the respiratory movements. The taking of exercise sufficiently vigorous to cause deep and[pg 093] rapid breathing should be a common practice and one should spend considerable time out of doors. If one has a flat chest or round shoulders, he should strive by suitable exercises to overcome these defects. Obstructions in the nostrils or pharynx should be removed.
Breathing Exercises.—In overcoming the habit of shallow breathing and in strengthening the lungs generally, the practicing of occasional deep breathing has been found most valuable and is widely recommended. With the hands on the hips, the shoulders drawn back and down, the chest pushed upward and forward, and the chin slightly depressed, draw the air slowly through the nostrils until the lungs are completely full. After holding this long enough to count three slowly, expel it quickly from the lungs. Avoid straining. To get the benefit of pure air, it is generally better to practice deep breathing out of doors or before an open window.
By combining deep breathing with simple exercises of the arms, shoulders, and trunk much may be done towards straightening the spine, squaring the shoulders, and overcoming flatness of the chest. Though such movements are best carried on by the aid of a physical director, one can do much to help himself. One may safely proceed on the principle that slight deformities of the chest, spine, and shoulders are corrected by gaining and keeping the natural positions, and may employ any movements which will loosen up the parts and bring them where they naturally belong.36
[pg 094] Serious Nature of Colds.—That many cases of consumption have their beginning in severe colds (on the lungs) is not only a matter of popular belief, but the judgment also of physicians. Though the cold is a different affection from that of consumption, it may so lower the vitality of the body and weaken the lung surfaces that the germs of consumption find it easy to get a start. On this account a cold on the chest which does not disappear in a few days, but which persists, causing more or less coughing and pain in the lungs, must be given serious consideration.37 The usual home remedies failing to give relief, a physician should be consulted. It should also