A Treatise on Anatomy, Physiology, and Hygiene Part 67

H.

The proximate principles, which are the most important in nourishing the body, are alb.u.men and fibrin. These const.i.tute the greater part of all the softer animal tissues, and are also found in certain cla.s.ses of vegetables, such as peas, beans, lentils, and many seeds. Hence, in many cases, a vegetable diet, especially if embracing any of those articles, would be sufficient to sustain life, even if no animal food should be eaten. But no animal can exist for a long time if permitted only to eat substances dest.i.tute of nitrogen, as in the case of a dog fed entirely on sugar, which lived but thirty days. And owing to this fact, Baron Liebig proposes to call substances used for food, containing nitrogen, "elements of nutrition," and those containing an excess of carbon, "elements of respiration;" since, according to his view, the food is necessary to support the growth of the body by replacing the effete and worn-out particles with new matter, and also to keep up the supply of fuel, in order to promote a sufficient degree of heat in the system. Accordingly, under the first division would be included all lean meats and vegetables, such as peas, &c.; while the fat of animals, vegetable oils, sugars, tubers, (as the potato,) and all other substances containing starch, would be included under the latter division.

I.

This definition of exhalants is from the theory of Haller and others.

It is now believed that the fluids exude through the thin coats of the blood vessels. This process is called _exosmose_, and is the _exhalation_ of old physiologists.

J.

It is a well-established fact, in animal and vegetable physiology, that membranes possess the property of allowing fluids and gases to pa.s.s through them in either direction, and also to permit two fluids to pa.s.s in opposite directions at the same time. This property is designated _endosmose_ when a fluid pa.s.ses from without a body inward; and _exosmose_ when the reverse takes place. The first is called _imbibition_. One of the most striking instances of this, in the human system, is shown in the lungs, where carbonic acid and water pa.s.s out through the mucous membrane of the bronchial tubes and air-cells; and the oxygen of the air enters the blood through the same membrane. By this process of imbibition, the oxygenation of the blood is much more readily and faithfully accomplished; inasmuch, as by the immense number of bronchial tubes and air-cells a larger quant.i.ty of blood is exposed to a greater portion of air, than if the blood were directly laid open to the atmosphere in a ma.s.s, or the air were immediately transmitted through it.

Since the function of respiration is to free the system of superfluous carbon and hydrogen, by union with the oxygen of the air, it follows that the greater the amount of the products to be expelled, the larger the quant.i.ty of oxygen will be required to effect this purpose, as we find to be the case with those who consume large quant.i.ties of food.

The quant.i.ty of oxygen daily consumed through the lungs by an adult is about 32.5 oz., and the carbon in the food 13.9 oz. But in order to convert this whole amount of carbon into carbonic acid, which pa.s.ses off through the lungs and skin, 37 oz. of oxygen are required; the remaining 4.5 oz. being absorbed by the skin. If the supply of food remain the same, while the amount of oxygen in the inspired air is diminished, the superfluous carbon will induce disease in the system, as is the case of those persons who are limited in their supply of air of a proper quality or quant.i.ty, and, consequently, have less appet.i.te for food than those who are abundantly supplied with air of the proper standard of health; and in children, who proportionally consume more food than adults, and who are more active, thereby causing a more rapid circulation of blood, and, consequently, the removal of more superfluous particles of matter.

In children we notice the need of air, by their disposition to be much in the open air, and often inspiring more deeply than is common in older persons. Also, if the carbon of the food does not have a requisite supply of oxygen from the air, or other sources, the body becomes emaciated, although nourishing food may be used. And on the other hand, if there be a diminished supply of food, but an abundance of atmospheric air, leanness and emaciation are sure to follow; owing to the fact that if the oxygen has no waste carbon from the body to unite with, it combines with the fat, and some other soft portions of the body, which the Author of nature seems to have provided for this very purpose; as is seen in the case of hibernating animals, who enter their places of winter abode sleek and fat, but crawl out in the spring not merely deprived of their fatty matter, but also with great diminution of all the softer parts, which have given up their share of carbon to supply animal heat. One important cause of emaciation in febrile diseases is the greater rapidity of the pulse and respiration, which consume more carbon than is afforded by the scanty supply of food that is taken, although profuse perspiration, which almost always occurs in some stages of fevers, greatly diminishes the full state of the body.

K.

The theory of Baron Liebig concerning the change which the blood experiences in color, in its pa.s.sage through the lungs, meets with the approbation of many physiologists, although there are some important difficulties in the way of fully receiving it. A chemical a.n.a.lysis of the blood shows it to be composed of alb.u.men and fibrin, together with some other substances, in small proportions, and always perceptible traces of iron. He attributes the change in color to the iron, as this substance enters into combination with carbon and oxygen. For, as the blood pa.s.ses through the trunks of the larger vessels and capillaries, it receives the carbon from the tissues which are continually transformed, and taking up the oxygen from the arterialized blood, forms carbonic acid, which unites with the iron, forming proto-carbonate of iron. This being of a gray color, he supposes it to be that which, with the other impurities of the blood, gives the venous blood the dark blue color. Then, as the blood comes in contact with the oxygen, as it is returned and exposed to this element in the lungs, the carbonic acid leaves the iron, which has a stronger affinity for oxygen than for carbonic acid, and forms the scarlet red peroxide of iron, that gives the characteristic color to the arterial blood. After this, as the blood is sent out through the smaller arteries and capillaries, it again gathers carbon and other impurities from the system, and becomes the dark, venous blood, thus completing the whole change of color in the circulation.

L.

As already mentioned, different articles of food have been divided into the azotized and non-azotized, or those which contain nitrogen as one of their const.i.tuents, and those which are nearly dest.i.tute of it.

Of these, according to Liebig, the azotized portions are simply to supply the waste that is continually going on in the body, and promote its growth in the early stages of existence, or, in other words, the nutrient portion; while the sugar, starch, &c., are mainly of use in the respiratory organs. The correctness of this view may be understood from the fact, that the inhabitants in the colder regions of the earth consume a much larger quant.i.ty of oil and fat than the residents of hotter climates; and also those dwelling in the temperate zones can eat with greater impunity a larger quant.i.ty of fat meats in the winter than in the summer, there being then so much more demand for animal heat than in the summer.

M.

The suggestion of using the bellows in asphyxia, is from the directions of that distinguished and veteran surgeon, Valentine Mott, of New York city. The directions in the first part of the paragraph are the most practical, and best adapted to the wants of the community.

GLOSSARY

AB-DUCTOR. [L. _abduco_ to lead away.] A muscle which moves certain parts, by separating them from the axis of the body.

AB-DOMEN. [L. _abdo_, to hide.] That part of the body which lies between the thorax and the bottom of the pelvis.

AB-DOMIN-IS. Pertaining to the abdomen.

A-CE-TABU-LUM. [L. _acetum_, vinegar.] The socket for the head of the thigh-bone; an ancient vessel for holding vinegar.

A-CETIC. [L. _acetum_, vinegar.] Relating to acetic acid. This is always composed of oxygen, hydrogen, and carbon, in the same proportion.

A-CHILLIS. A term applied to the tendon of two large muscles of the leg.

A-CROMI-ON. [Gr. +akros+, _akros_, highest, and +mos+, _omos_, shoulder.] A process of the scapula that joins to the clavicle.

AD-DUCTOR. [L. _adduco_, to lead to.] A muscle which draws one part of the body toward another.

AL-BU-GINE-A. [L. _albus_, white.] A term applied to white textures.

AL-b.u.mEN. [L. _albus_, white.] An animal substance of the same nature as the white of an egg.

A-LUMIN-UM. [L.] The name given to the metallic base of alumina.

ALVE-O-LAR. [L. _alveolus_, a socket] Pertaining to the sockets of the teeth.

AM-MONI-A. An alkali. It is composed of three equivalents of hydrogen and one of nitrogen.

A-NASTO-MOSE. [Gr. +ana+, _ana_, through, and +stoma+, _stoma_, mouth.] The communication of arteries and veins with each other.

AN-A-TOMI-CAL. Relating to the parts of the body, when dissected or separated.

A-NATO-MY. [Greek +ana+, _ana_, through, and +tom+, _tom_ a cutting.] The description of the structure of animals. The word _anatomy_ properly signifies dissection.

ANGU-LI. [L. _angulus_, a corner.] A term applied to certain muscles on account of their form.

AN-I-MALCU-L. [L. _animalcula_, a little animal.] Animals that are only perceptible by means of a microscope.

ANNU-LAR. [L. _annulus_, a ring.] Having the form of a ring.

AN-TICUS. [L.] A term applied to certain muscles.

A-ORTA. [Gr. +aort+, _aort_; from +ar+, _ar_, air, and +tre+, _treo_, to keep.] The great artery that arises from the left ventricle of the heart.

AP-O-NEU-ROSIS. [Gr. +apo+, _apo_, from, and +neuron+, _neuron_, a nerve.] The membranous expansions of muscles and tendons. The ancients called every white tendon _neuron_, a nerve.

AP-PA-RATUS. [L. _apparo_, to prepare.] An a.s.semblage of organs designed to produce certain results.

AP-PENDIX. [L., an addition.] Something appended or added.

AQUE-OUS. [L. _aqua_, water.] Partaking of the nature of water.

A-RACHNOID. [Gr. +arachn+, _arachn_, a spider, and +eidos+, _edos_, form.] Resembling a spider's web. A thin membrane that covers the brain.

ARBOR. [L.] A tree. _Arbor vit._ The tree of life. A term applied to a part of the cerebellum.

ARTE-RY. [Gr. +ar+, _ar_, air, and +tre+, _treo_, to keep; because the ancients thought that the arteries contained only air.] A tube through which blood flows from the heart.

A-RYT-ENOID. [Gr. +arytaina+, _arutaina_, a ewer, and +eidos+, _edos_, form.] The name of a cartilage of the larynx.