PHYSIOLOGY APPLIED TO HEALTH AND It
Tins able work reached us some months since, when the pressure of publication was great, and the necessity of immediate attention to more perishable wares induced us to reserve, on a shelf of honourable postponement, a few of those that we knew to be en- dowed with a vitality to outlive the season. In the mean time, it has reached a second edition.
The volume consists of a series of connected essays on the struc- ture, functions, and uses of some of the most important parts of the human frame,— the skin; the muscles, as the mechanical means of motion and exercise; the bones • respiration ; the ner- vous system, and the brain; to which, in tile second edition, has been added a sensible chapter on the treatment of insane persons. It should be clearly understood, that the treatment of disease forms no part of the writer's plan, nor does he make any preten- sions to new discoveries. The merit of the work consists in the plain and intelligible manner in which it has popularized science,. and applied it to the most important practical purpose—the pre- servation and iinprovement of health. To make every one so far acquainted with his own body, that, having a clear idea of the general laws which govern its existence and regulate its wellbeing,. he may know what course of conduct to pursue and what to avoid in the seemingly trivial practices of daily life, is ono object of the author. Another is, to apply this knowledge to the bodily and mental education of the young, especially in the nursery and the school. Over the whole of so extensive a field, we cannot travel ; but there are two important points — the skin, and the lungs— on which we will briefly touch. It is known to every person, hewc7er superficially acquainted with physiology, that all living beings are in a constant state of change. Life is maintained, growth supported, strength kept up,. by various foreign substances which are constantly taken into the system, and as constantly thrown off to give place to fresh matter. The chief organ by Which such foreign substances as are fitted to sustain the life of man are turned to nutriment, is the stomach. In throwing off the old, altered, or useless particles," the kid- nies, the lungs, and the skin, assist the stomach ; " and although the precise amount of perspiration may be disputed, still the greater number of observers agree, that the cutaneous exhalation is more abundant than the united excretions of both bowels and kidnies." In what way these two last organs act either in repairing or re- lieving the system, is designedly left untold by Dr. COMM All that relates to the skin, whether as regards its nature, its func- tions, or its uses—the alliance which it forms with other organs, the causes that disorder it, the effccts which flow from its disorder, and lastly, the practical uses to which know ledge may be turned
in preventing its derangement or guarding against its effects—are explained in a clear, masterly, and interesting manner. Pas- sing over an account of some curious experiments made to estimate the actual quantity of matter thrown off by insensible perspiration,. we twee to a passage explaining
THE RATIONALE OF COLD.
What we have considered relates only to the insensible perspiration. That which is caused by great beat or severe exercise is evolved in much greater quantity; and by accumuldring at the surface becomes visible, and forms sweat. In this way, a robust man iii lose two or three pounds' weight in the course of one hour's severe exertion; and if this be suddenly checked, the consequences in certain states of the system are often of the most serious description. When the surface of the body is chilled by cold, the blood -vessels of the skin become contracted in their diameter, and hinder the free entrance of the red panicles of the blood, which are therefote of necessity collected and retained in greater quantity in the internal organs, where the heat varies very little. The skin consequently becomes pale, sod its papilhe contract, funning by their erection what is called the goose's skin. In this state it becomes less tit for its uses; the sense of touch can no longer •iicely discriminate the qualities of bodies, and s cut or bruise may be received with compluatively little pain. From the oppres- sion of too much blood, the internal organs, on the other hand, work heavily : the mental faculties are weakened, sleepiness is induced, respiration is oppressed,. the circulation languishes, and digestion ceases,- and if the cold be very intense,. the vital functions are at last extinguished, without pain and without a struggle. This is a picture of the ext.-eme degree ; but the same causes which, in an ag- gravated form, occasion death, produce, when applied in a minor degree, effects equally certain, although not equally marked or speedy in their appear- ate These extreme cases, as we all know, are of rare occurrence; and indirectly fatal cases from suppressed perspiration, though common enough, are not so common as might d priori be supposed. When the excretions from the skin are suppressed, the other organs come to their assistance, and perform an increased amount of duty, according to the nature of the case, the constitution of the patient, or to their own strength. But though this provident care of Nature it vents the disease or death which otherwise would ensue frcm
such an apparently slight cause as a sudden change of temperature, there is still this inconvenience and danger attending the dein oge- ment of a singlelimetion—that if any one of the organs connected with it is weak, that organ will suffer in its health from the in- creased labour thrown upon it. And as the lungs excrete equally with the skin, hence their peculiar liability to derangement from mere cold, which is followed by cough, consumption, and death.
When the lungs are the weak parts, and their lining membrane is habitually relaxed, accompanie4 by an unusual amount of minima secretion from its sur• face, cold applied to the skin throws the mass of the blood previously eirculat - jog there inwards upon the lungs, and increases that secietion to a high degree. Were this secretion to accumulate, it would soon fill up the air-cells of the lungs, and cause suffocation ; but to obviate this danger, the Creator has so constituted the lungs, that any firreign body coining in minuet with them ex- cites the convulsive effort called coughing, by which a violent and rapid expira- tion takes place, with a force sufficient to hurry the foreign body along with it ; just as peas are discharged by boys with much firrce through short tubes by a sudden effort of blowing. Thus, a check given to peripiration, by dii•linishing the quantity of Wood previously circulating on the suffice, naturally leads very often to increased expectoration and cough, or, in other words, to common cold.
For the other powers of the skin, as shown in absorption and sensation or the faculty of touch, as well as for the details of the very sensible and practical directions as to the modes of managing the skin, we must refer the reader to the volume. But the results are soon told : keep warm, and keep clean. Wear sufficient cloth- ing, according to your constitution and the season ; and wash often. The strong and healthy may use the cold or shower bath ; the delicate, the warm or tepid bath; and, with common care, there is never any danger of cold. If these cannot conveniently be obtained, there is sponge, w.ater, and vinegar, or salt : there is the flesh- brush, there is flannel, and a coarse cloth. We wash our dogs; we groom our horses; though they are living in a state of nature, and their skins, being constantly uncovered, are less tender and better situated for throwing off excretions. "Our ancestors im- pure." and ourselves, have opposed Nature in every way—ill our eating, our drinking, our clothing, our houses, and our habits ; yet the majority—with many too who have not the plea of poverty —cover up the greater part of their bodies from year's end to year's end, and allow the imperceptible particles of perspiration to accu- mulate upon the skin without removal (unless a Dog-day sun forces them into a bath, from sheer want of power of endurance); and then they wonder they are chilly, listle. s, and liable to take cold; their mode of living, or their occupation, very probably dis- ordering more or less the other excretory organs, even if they were originally healthy, and thus rendering additional power in the skin desirable or indispensable.
As we have already said, we must pass over a subject closely connected with perspiration—muscular exertion, or exercise— why, when, where, how it should be used, and to what extent. We must also leave unnoticed a matter closely connected with exercise—the nervous system ; as well as the curious description of bone, and the valuable hints to parents upon the early manage- ment of children in reference to this part of the human frame. We come to a matter of more general and constant concern,—the air we breathe, and the function of respiration by which we breathe it. Every one knows, from the old Whig toast—when as yet Whigs toasted the Liberty of the Press—that "without air, we die :" it is known that a similar result attends upon "foul air ;" andthat in an impure atmosphere, we feel uncomfortable, languid, and un- well, whilst many faint,—all which unpleasantnesses are quickly alleviated on removing into the open air. The reasons of these results are of course known to the scientific : we have never seen them so popularly explained as here— The blood circulating through the body is of two different kinds; the one, red or arterial, and the other, dark or venous blood. The former alone is capable of affording nourishment and of supporting life. It is distributed from the left side of the heart all over the body, by means of a great artery or blood- vessel called the aorta, which subdivides in its course, and ultimately terminates in myriads of very minute ramifications, closely interwoven with, and in reality constituting a large portion of, the texture of every living part. On reaching this extreme point of its course, the blood passes into equally minute ramifica- tions of the veins, which, in their turn, gradually coalesce and form larger and .larger trunks, till they at last terminate in two large veins, by which the whole current of the venous blood is brought back in a direction contrary to that in the arteries, and poured into the rip/at side of the heart. On examining the -quality of the blood in these two systems of vessels, it is found to have under- gone a great change in-its passage from the one to the other: The florid hue which distinguishes it in the arteries has disappeared, and given place to the lark colour characteristic of venous blood. Its properties, too, have changed, and it is now no longer capable of sustaining life. Two conditions are essential to the reconversion of venous into arterial blood, and to the restoration of its vital properties. The first is an adequate provision of new materials from the food, to supply the place of those which have been expended in nutrition ; and the second is the flee exposure of the venous blood to the atmospheric air. The first condition is fulfilled by the chyle or nutrient principle of the food being regularly poured into the venous blood, just before it reaches the right side of the heatt ; and the second, by the very important process of respiration, which takes place in the air-cells of the lungs, and which it is our present ob- ject to explain. The venous blood having arrived at the right side of the heart, is propelled by the contraction of that organ into a large artery. leading directly, by separate branches, to the two lungs, and hence called the pubnonary artery. In the in. numerable branches of this artery, expanding themselves throughout the sub- stance of the lungs, the dark blood is subjected to the contact ot the air inhaled in breathing; and a change in the composition both of the blood and of the in- haled air takes place, in consequence of which the former is found to have as- sumed its florid or arterial hue, and to have regained its power of supporting life. The blood then enters n l i lll ite venous ramifications, which giadually coalesce into larger branches, and at last terminate in four large trunks in the left side of the heart; whence the blood in its arterial hum is again dist' ibuted over the body, to pursue the same course and undergo the same changes as hefole, The exposure of the Hoot to the action of the air, seems to be indispensabie to every variety of animated creatures. In man and the more pertiNt of the lower animals, it is car: ied on in the lungs, the structure of which is admirably adapted for the purpose. In many animals, however, the requisite action is effected without the intervention of lungs. In fishes, for example, which live itt a dense medium, and do not breathe, the blood circulates through the gills; which, being constantly and directly in contact with the water, are therefore inure accessible to the action of the air which the water contains, and much better adapted than lungs would be to the medium iu wide!' fishes live. Ic worms, on the other hand, and many similar animals, no distinct organ is set apart for the purpose ; but the aeration of the blood takes place at the surface of the body, by means of pores in the skin, called spiracao, specially adapted to this end, and which cannot be shut up or obstructed any more than the real lungs or gills, without inducing death. So necessary, indeed, is atmospheric air to the vitality of the blood, in all classes of animals, that its abstraction in- evitably induces death ; anal a fish can no more live in water deprived of air, than a man could in an atmosphere deprived of oxygen. And thus the fist' requires a renewal of air, and perishes when it is denied, exactly as man does in similar circumstances.
It is unnecessary to follow our author through his description of the lungs, or of the mechanical means by which they perform their functions ; or to say any thing of exhalation, which assists in throwing off old and useless matter, by a process analogous to that of perspiration. Upon another important function, the miter shall speak for himself— Absorption, in like manner, takes place from the lining membrane of the lungs, as we have seen it do in the skin. When a person breathes an atm°. sphere loaded with fumes of spirits, of tobacco, of turpentine, or of any other volatile substance, a portion of the fumes is taken up by the absorbing vessels of the lungs, and carried iuto the system, and there produces precisely the saute effect9 as if introduced into the stomach. It has occasionally happened that person has unwarily become intoxicated in thia tray ; and the lungs thus become a ready inlet to contagion, miasmata, and other poisonous influences diffused through the air which we breathe.
It will easily be seen from all this, why pure air is such a ne- cessary of life. By what processes it acts upon the lungs, or the lungs upon it, is not easily explained. It is only known, that the air is deprived of a portion of its oxygen, and that it is quickly rendered corrupts- or even deadly, if a fresh supply be altogether shut out, or admitted in very minute quantities. An animal con- fined in closely-stopped glass, is an instance of the last : for a short time it exhibits no signs of inconvenience, but it soon becomes uneasy, and then dies. The Black Hole of Calcutta is an example of the first. The experimentalist who, after confia- ing a mouse in a glass, shuts himself up in a small close cham- ber—the schoolboys, who are confined by their master in the ex- hausted atmosphere of an ill-ventilated room — the ill-educated senators, who night after night inhale the pestiferous air of St. Stephen's Chapel—differ greatly in degree, but not in kind, from the mouse in a bottle, or the Company's servants in the Black Hole. It is possible that some natural vigour of constitution may enable a few to escape without injury to health, or pernicious eacts upon life itself,—just as habit, and extraordinary mental energy, will enable some to defy that sense of languor and oppression which comes over us after close application in a close room. But those who would preserve their bodily health, and maintain their mental vigour, must take measures to obtain a supply of pure air. Who knows how much of the incapacity, dulness, and idleness of the present House of Commons, arise from the air they breathe? " The Bill" has reformed, in some sort, the political corruption; let us next take in hand the atmospherical.
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