Baths and Bathing

CHAPTER I.. The Physiological Action of Baths.

THE PHYSIOLOGICAL ACTION OF BATHS.

Since the influence of baths is exerted primarily upon the skin, and through the medium of the skin, upon the deeper-lying tissues and organs of the body, it is an absolute necessity for the reader at the outset to be made aware of the structure of the skin and its functions, as well as the relations which it bears to deeper-lying organs.

If the skin, say of the thumb, be looked at with a lens of moderate power, its surface is seen to be arranged in ridges and furrows, like a ploughed field; and at frequent intervals along the ridges are little depressions, which are known as the pores of the skin. These pores are the openings of the sweat ducts, and it is through these pores that the perspiration exudes. They are exceedingly numerous, and it has been calculated that there are as many as 2,800 to every square inch of surface, or about seven millions of them altogether. The ridges are seen to be divided into a series of minute hillocks, or papillæ, which are arranged in lines. These papillæ are the organs of touch, and are probably as numerous as the pores. They contain in their interior either loops of blood-vessels or nerve-endings.

These nerve-endings in the papillæ are of three kinds, which are readily distinguishable, and are known as tactile corpuscles, pacinian bodies, or end bulbs, according to the form which they take. Between the superficial and deep layers of the skin, the so-called cuticle and cutis, is a layer which partakes somewhat of the character of both. This is called the rete mucosum, and it is here that the pigment, found in the skin of the negro and in certain parts of the skin of white races also, is located.

Beneath the skin, in the subcutaneous tissue, are situated the sweat-glands, which are microscopical bundles of tubing, having one end running through the skin to terminate in the pores. These tubes are, or rather would be, if straightened out, about a quarter of an inch long; and it is estimated that the length of them in the entire body is about 28 miles! They pass through the upper layer of the skin or cuticle spirally, so that, although it is an easy matter for fluid to pass out, the passage in the opposite direction is by no means so easy. Each sweat-gland is plentifully supplied with blood-vessels, and is surrounded by a thin muscular coat, which is presumably able to exert, by its contraction, a certain amount of pressure, and so drive the secretions of the gland onward towards the pore, or external aperture.

The hair follicles, like the sweat-glands, are situated in the subcutaneous tissue. They are hollow receptacles, from the bottom of which the hairs grow. Alongside of each of these hair follicles is a pair of glands, called the sebaceous glands, which provide that small quantity of natural grease with which our hair is supplied. These glands resemble little bunches of grapes. The hair follicles are also furnished with a couple of small muscles, which, by their contraction, can cause a sensible erection of the hair. In certain parts of the skin there are glands which furnish a special odorous secretion. These are most plentiful in the arm-pits and between the toes. In the skin itself, and immediately beneath it, is a network of “lymphatic” vessels, whose function, it would seem, is mainly to drain the tissue of waste products. These vessels run towards the “lymphatic glands,” which, when enlarged, are often recognisable at the side of the neck, and which are very generally distributed throughout the body. In certain parts of the skin are special cells containing pigment.

Thus we see that the skin, which to the casual observer is an almost structureless membrane, is in reality a most complex and elaborate organ, richly supplied with blood-vessels, lymphatic vessels, and nerves, having its millions of papillæ and pores, and its miles of sweat-ducts. The hair follicles, with their sebaceous glands and muscles, are also to be reckoned by the million, and its odoriferous glands and special pigment-bearing cells probably by the thousand.

What are the various uses of this elaborate organ? In the first place, it serves as a protection to the softer parts beneath. Secondly, it serves to regulate the temperature of the body, by preventing, on the one hand, the too rapid radiation of the natural heat, and, on the other, by providing a very large surface for the evaporation of the constantly exuding perspiration, it prevents the overheating of the body. Thirdly, it is constantly removing from the body certain effete materials. These are the scales of the cuticle (which we remove whenever we wash and rub the surface), the perspiration, and the sebaceous, or greasy secretion. The amount of sweat varies immensely; it may be almost nil, or as much as a pint in an hour. The secretion of sweat is influenced by the temperature of the air, by exercise, by the drinking of fluids (especially warm fluids), and notably by the emotions. There can be no doubt that the secretion of a certain amount of sweat is necessary for perfect health; and it is the common experience of all that the checking of perspiration is very liable to be followed by dangerous internal congestion.

It has been demonstrated on some of the lower animals that, if the skin be shaved and varnished, death speedily ensues. This has been spoken of as a sort of cutaneous suffocation, death taking place owing to the charging of the blood with matter which should have been removed by the skin. It has been asserted, however, that death is due to cold in these cases; and it has certainly been demonstrated that animals so treated live much longer provided they be kept warm by a layer of cotton wool. Sometimes the skin is superficially destroyed by accidental burning or scalding, and it is well recognised that a burn or scald is dangerous to life in proportion to its superficial extent, rather than to its depth or severity.

The blood-vessels of the skin vary much in size under different circumstances, and the different degrees of pallor or redness of the skin are due to the condition of these superficial blood-vessels. The phenomenon of blushing is well known; and this should serve to remind us that the emotions can not only influence the amount of perspiration, but the size of the cutaneous blood-vessels. The intimate relations existing between the skin and the great nerve-centres should never be lost sight of.

The cutaneous blood-vessels enlarge in certain fevers, as scarlet-fever and measles; they can be made to enlarge also by the application of warmth, or irritants, such as mustard, or the stroke of a whip. Contraction of the blood-vessels is most marked in conditions of fear, or as the result of the prolonged application of cold.

Not only have the nerve-centres a great influence on the skin, but the skin is capable of exerting a great influence on the nerve-centres. This is not to be wondered at, when we bear in mind the myriads of nerve-bearing papillæ with which the skin is beset. When the soles of the feet are tickled, the legs are involuntarily moved; and when the arm-pits and sides of the chest are tickled, loud laughter is the result. These two phenomena are examples of what is known as reflex action, i.e., the tickling produces an effect upon the nerve-endings in the skin, and this effect travelling to the nerve-centres (the spinal cord or brain) is reflected to the muscles, and produces movement of the leg or laughter. When the body is suddenly immersed in cold water, a not uncommon result is a shivering and a chattering of the teeth; and when cold water is sprinkled on the forehead or chest, deep inspiration and a catching of the breath is produced. These are examples of “reflex movements,” due to impressions made upon the nerves of the skin; and since many of the results of bathing are undoubtedly due to this kind of reflex action, it is very important to bear it constantly in mind. The connection between the nervous centres (the brain and spinal marrow) and the skin is shown also in the occurrence of what is known as goose skin, or cutis anserina, which is caused not only by the application of cold to the surface of the body, but even more readily by the mental states which make the “Hair of our flesh stand up.” The rationale of this phenomenon is the contraction and shortening of the little muscles which we have seen to be in intimate relationship with the hair follicles. There can be no doubt also that the pigment cells, which are scattered thinly throughout our skins, are subject to the control of the nervous centres, and it is well known that the tint of the complexion will sometimes vary with emotional states, as it certainly does with physical states. These considerations are sufficient to show that the skin plays a most important part in the animal economy, as a protective, a secreting, a vascular, and a nervous organ.

Continue reading Baths and Bathing free in the Wunder reader →