Physiology: general and osteopathic; a reference and text book for osteopathic students and physicians

Front matter

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Introduction

The study of physiology is far from being a complete science. Since this subject deals with the structure and functions of living organisms it becomes much more difficult to measure and express our results in numbers than in such sciences as physics and chemistry, and until we are able to do this physiology will continue to be the results of theoretical speculation rather than a definite science. This, however, is wholly different from saying that there is nothing definitely known relative to the functions of living structures, for on the other hand we are greatly indebted to the many research workers and clinical investigators who have so earnestly and conscientiously solved many problems along these lines. The ultimate purpose of the development of physiology into a definite science should be that of gaining such information of living organisms that physicians may be able to treat human ailments intelligently. Other purposes, such as the addition of general scientific information to other sciences, is of course a justifiable one, but it seems that this should be a secondary consideration. Research workers in physiology must, however, proceed along strictly scientific lines and not allow themselves to be biased, but must follow the results of their findings regardless as to where they may lead.

Work in physiological research has for the most part been done by instructors and assistants in medical colleges, and they have devoted much of their time to research work pertaining especially to drug therapy. During more recent years, since the endowed universities have taken up original scientific research in physiology, the work on this subject as well as in other branches has been more general.

In medical as well as other sciences it is generally true that the science follows the art of practice. In medical practice this is especially true except that the results of scientific research — the science — has failed to confirm the methods of practice.

Osteopathy is a comparatively new system of practice, having existed for only about twenty years, and yet much valuable research work has already been done along new and wholly different lines. We believe that no other school of practice has done as much original scientific investigation pertaining to the theories of its methods of treatment according to the length of time it has existed, and I am sure that no other school has been more successful in confirming its theories by the results of its research. That the osteopathic theory is fundamentally scientific no one who has kept up with the results of its growth, research, and practice can doubt. The original" plan and the fundamental principles of osteopathy were given by Dr. Andrew Taylor Still, a man particularly adapted to research and original investigation and who now, in his eighty-fifth year, is still an active student. Dr. Still has been a frequent and most welcome visitor in my classes at the American School of Osteopathy, and I am very greatly indebted to him for much valuable information received along osteopathic lines.

Because the science of physiology is so broad, and because it involves so many different phases of the organic and inorganic sciences, no one individual can ever hope to obtain a thorough knowledge of the entire subject. I, therefore, frankly admit my inability to write a book on the subject without the aid of those whose original investigation and experience have been much more far reaching than my own. In the preparation of this book I admit frequent reference to the best modern authorities in general physiology, such as Starling, Howell, Stewart, Sherrington, Luciani, Landois, Schafer, and many others. For principles of physiology pertaining especially to osteopathy I have consulted the writings of Burns, McConnell, Whiting, R. K. Smith, Hulett, Hazard, Farmer, Tasker, and others. That these authorities might receive due credit I have frequently quoted from their most recent publications.

In order that this book might be thoroughly reliable, so far as the part on general physiology is concerned, I have referred to and quoted from only the best authorities on this subject, using only most recent editions of their books. In order that the part pertaining to the osteopathic principles of physiology might be reliable I have asked assistance from our foremost research workers along these lines.

Osteopathy is a system of healing which considers the fundamental relations of structure to function and the co-ordinative functions of all body structures acting together as a unit. The workers in general physiology, it seems to me, do not give these problems due consideration and the osteopathic student cannot, therefore, get sufficient understanding of the subject from a study of the general text-books. This book has been prepared for the purpose of meeting this demand. It is offered only as a contribution to the general subject of physiology, as a special contribution to osteopathic literature, and is not intended to revise the whole trend of physiological or osteopathic thought. No attempt has been made to conform to the theoretical conventionalities so common to the general texts on physiology, but on the other hand the authors have endeavored to make the book thoroughly osteopathic because it is written for the use of osteopathic students and physicians. The book has been arranged in two parts, the first giving the principles of general physiology, omitting as much as possible of the seemingly unnecessary theory, the second giving s the results of original osteopathic research. I am very deeply indebted to Drs. McConnell, Burns, and Whiting for the excellent summaries of their research work, and to Dr. Millard for the drawings which he has prepared and from which all the colored plates have been made. I feel highly sensible of my deep obligation to these doctors, because without their assistance the book could not have been prepared, and I trust that the plan of co-operation will be continued and that it may result in the development of much valuable osteopathic literature in the future. I am also indebted to the editors of the Journal of the American Osteopathic Association, the Herald of Osteopathy, and the Journal of Osteopathy for allowing me the use of some of their colored plates, and to the C. H. Stoelting Company for the use of a few of their cuts.

STRUCTURE AND FUNCTION.

The existence of all living organisms is dependent upon the intimate relations which exist between the various component parts or structures of the organism and the work or functions which these structures have to perform.

In primary physiology we are taught that "man is a machine" and that his various working parts have their specific kind of work or functions to perform and that, failing in this, a perversion of function results and this failure of the normal function means disease. The study of the fundamental relations of structure to function should then be the aim of every student of physiology.

By the term structure is meant the body framework, its organs and other constituent parts. The term body tissue is applied to a structural part of the body consisting of an aggregation of similar cells having a similar function or similar functions, e. g., bone, which forms the frame work; cartilage, which pads the joints and allows movement without wear; muscle, the contraction of which causes movement of the body levers, the bones; and nerve tissue, which is the body messenger and serves to connect the various structures in their functional relations and to regulate these functions. It will, of course, be left for the histologist to explain the minute or microscopic structure of the various tissues.

Relations of Structure to Function. — Function may be defined as the specific work of an organ or tissue of the body. An organ is a specialized structure whose function is some special kind of work. In order that any tissue or organ may perform its normal function it must itself be normal in its development, its growth, its cellular composition, and in its structural relations with other organs. The last of these requirements is probably most 10 essential because, if the structural relations are right, normal development, growth, etc., will follow.

If, on the other hand, any abnormal structural relations exist these may affect the blood or nerve supply or in some other way interfere with its development, growth, or the functional activities of its component cells, thus affecting the functions of the organ. It is well known that the functions of any individual structure depend not only on its own normal structural relations, but to some extent upon the functional activities of other structures. If the heart, for example, fails to pump the necessary amount of blood to any certain organ or if the nerve supply for any reason is insufficient, thus rendering the regulation of its functional activities abnormal, that structure fails to perform its normal kind or amount of work. Since the various organs of the body bear certain functional relationships to each other, any perversion of the functions of one structure may materially interfere with the functions of other structures, and thus we have an example of the unity of body structures and their functions.

This dependence of function upon structure may again be compared to the working of a machine. If at any time a certain mechanism fails in its proper adjustment the work of that part is impaired or lost, and in most cases the entire machine is valueless until this one part is repaired.

Structure Depends upon Function. — In the above paragraphs it has been shown that normal function depends upon normal structure and now we must state the converse, viz., that normal structure is dependent upon normal function, which is also true. To illustrate we may use the example of the blacksmith's arm to show how cultivation of the function tends to develop and normalize structure, or on the other hand how, when one fails to take the necessary amount of exercise, his muscles atrophy and become weak. In future chapters the more complicated and intricate relations will be discussed which show these same principles.

Certain laws of physics apply also to the body as well as to other mechanisms. The laws of conservation and transformation of energy, for example, hold good for the animal machine. The source of energy is the food and air used as fuel. It may be transformed, transferred, or lost, but cannot be created within the body. The efficiency of the body machine is much greater than that of other machines, but here again the efficiency depends upon the degree of perfection of its structural relations.

Body Repair. — The body machine has one marked advantage over other machines and that is that it maintains its own repair shop. Certain cellular elements of the body, the red blood corpuscles, serve to replenish the various tissues with oxygen and the blood in this and other ways repairs tissue as it wears and also furnishes material for energy to its muscles and other working organs. The blood also carries other cells, the white blood corpuscles, which may be called scavenger cells, whose function is to carry away waste and protect against the invasion of bacteria, etc.

From the above paragraphs it may be seen that the body is an automatic machine in that it repairs its own wear and regulates its own work. Normal structure and structural relations mean normal functions and this stated in the converse, viz. , that normal function cannot result from abnormal relations, is the osteopathic theory of disease. Just so long as normal structural and functional relations of the body machine are normal the individual will show evidence of that phenomenon which we call life.

Physiology may be defined as that branch of science which treats of the various changes and processes occuring in the animal organism during life.

Physiological changes are those changes, whether physical or chemical in nature, which occur in the normal living body. The term metabolism is generally attached to these changes and usually applies to physiological chemical changes w T hich occur in the various tissues. Metabolism may be either constructive, a building or forming process, anabolism, or it may be destructive, a breaking-down process, catabolism. Changes anabolic in nature occur in tissue building, cell formation, etc., in which protein material from the foodstuffs, for example, is built into living tissue substance; and changes catabolic in nature occur in the destructive oxidation processes of certain foods, carbohydrates, fats, etc., the result of which is the liberation of heat and other forms of energy which yield power to do work.

These changes occur in all living organisms, animals and plants, and are necessary for the life processes of the organisms. In the lower forms of life, such as the amceba, all necessary life processes can be effected in the one simple cell of which the animal consists.

There are certain essential functions necessary to the life of every living animal, regardless of its scale of development. These are known as the essential physiological functions of protoplasm. They are metabolism, which has been defined; movement, by virtue of which animals are enabled to move or change their environmental conditions, which in case of the lowest forms consists of an amoeboid movement, by means of which the animal may adjust its body to new food supplies, etc.; the third function is growth, a process of continued constructive metabolism; fourth, reproduction, the process by means of which the animal reproduces its kind; the fifth, irritability, or the quality of responding to a stimulus. A sixth is sometimes given, which is a specific one and refers to some function of a specialized or highly differentiated structure.

In the higher forms of life these various functions are performed by organs highly differentiated and adapted for the performance of some one or more special functions. Movement in the higher forms, for example, is effected by the musculature, irritability by the system of nerves, etc. This differentiation of structures for the purpose of performing these special and separate functions enables the higher animals to do work and perform the various life processes much more perfectly, and constitutes a plan of physiological division of labor.

The Cell Theory. — Early in the eighteenth century the theory was advanced by Schleiden and Schwann, supported by other observers, that the cell constituted the histological basis of all animal structure. Since that time various workers in the biological sciences have developed this idea into a very explanatory theory of all life processes, the main principles of which are discussed in the following paragraphs :

1. The cell constitutes the anatomical and physiological unit of the organism, and the life processes of the individual organism are determined by the nature of the various cells which compose it.

2. Anatomically the various cells have undergone various processes of differentiating changes during the phylogenetic evolution of the organism, and now in the higher forms of life these specially differentiated structures which have resulted have the power of performing specialized functions according to the nature of the structure.

3. The cell is to the organ as the organ is to the body; that is, the functional activities of the organ depend upon the nature of the cells which compose it, just the same as the functional activities of the body as a whole depend upon the nature of its various organs.

4. The unity of functional relationships of the body as a whole depends upon the completeness of the functional activities of its various organs, and in turn the unity of function of the organ depends upon the functional activities of its various cells.

5. Every cell in the organ bears a certain functional relationship to every other cell of that structure, every organ of the body bears certain functional relations to every other organ, and the maximum of perfection of the various functions of all cells and organs renders to the body as a whole the sum total of perfect functional activity or health.

6. By the physiological division of labor, then, all of the various structures have special functions to perform, and any one of these failing in its function may cause an unequal balance or perversion of function and the result is disease.

Since normal function can be effected only by normal structure and since also normal structural relations must exist in all tissues, because of the inter-relations existing between the various structures, any perversion of structure may and usually will result in abnormal function, and this is the osteopathic theory of health and disease.

General physiology is that branch of science which treats of the various functions of the living animal. Special physiology is a branch of general physiology which teaches the special functions of some specialized structure or structures. Human physiology refers to those physiological changes occurring in the human body. Cellular physiology refers to those physiological changes occurring in the cell. Osteopathic physiology is that branch of general physiology which considers especially the relations of structure and function and the unity of these combined functions.

Chapter I. Body Fluids

In the lower forms of life the food of the single-celled animals is contained in the fluids in which they live, and likewise the body excreta of these simple forms is thrown off into and carried away by these fluids. The animal only needs to move a short distance to bring itself into relation with new food supplies in its surrounding medium. As the animal body becomes more complex in the higher forms of life this method of supplying its cells with food and relieving them of their wastes becomes impossible, and there originates a demand for a new structural system for supplying this function, and the demand is supplied by the bJood-vascular system. This system, which consists of closed tabes in which the body fluids circulate, serves the functions of carrying food supplies to the va rious tissues, removing the waste products of cell metabolism, and other functions to be discussed later. These fluids consist of blood and lymph and the serums from these fluids, which are found in the various extravascular spaces in the body. In case of the blood, it is first pumped from the heart through the arteries and into the thin-walled capillaries, where it comes in almost direct contact with the cells of the various tissues. Here certain contents of the blood are given up to these tissues and certain wastes from the tissue cells are emptied back into the blood stream. In some instances., as in the case of those vessels which supply the intestinal tract, food materials are taken up by the blood and carried to other tissues where they are needed or carried to some storehouse, as in case of the liver, and kept for future use. After the blood leaves the capillaries it passes into the veins and is carried back to the heart to begin its circulation anew.

Not all of the tissue wastes are emptied back into the blood stream. Some go by another route, the lymph channels. The lymph vessels are small, thin-walled tubes containing valves to prevent back-flow, and serving the function of carrying the extravascular fluids back to the veins.

BLOOD.

General Properties. — Blood has an average specific gravity of 1.055, varying under certain conditions within very narrow limits. The specific gravity of blood is best determined by comparing with liquids of known density. A mixture of chloroform and benzol may be so prepared that the solution has a specific gravity of 1.055. A drop of fresh blood is allowed to fall into this solution. If it sinks it is known to be heavier, and if it floats on the surface it is known to be lighter than the test fluid. There are certain instruments sometimes used for this purpose, but they are not of any great value in practical determinations. The specific gravity of the blood varies slightly with age, sex, time of day (being slightly higher at night), etc., but this is of no practical consideration. Blood is normally neutral in reaction when tested with phenolpthalein as an indicator, bub may be slightly alkaline when tested with litmus.

The color of blood varies from that of scarlet in the arteries to purplish in the veins. The presence of oxyhemoglobin in arterial blood gives the scarlet color, and the intensity of the color varies with the amount of oxyhemoglobin. The oxygen of the hemoglobin is given up to the tissues as the blQod passes through the capillaries; thus the change of color in the veins.

CONSTITUENTS OF BLOOD.

Plasma is the liquid portion of the blood in which the corpuscles float. Its specific gravity varies from 1.026 to 1.030. Serum is the liquid portion of the blood after coagulation, and represents the plasma minus fibrinogen. The clot consists of corpuscles and fibiin. Stewart compares these as follows:

Plasma + fibrin (ogen) = serum.

Corpuscles -\- fibrin = clot

Plasma + corpuscles = serum -f- clot = blood.

Red Blood Corpuscles. — The red blood corpuscles or erythrocytes are discal, biconcave bodies, 7.5 micra in diameter, 2.5 micra in thickness at the periphery, and from 1 to 2 micra thick at their mid-portion. The normal number of erythrocytes for the adult male is 5,000,000 per cubic millimeter and for females 4,500,000 per cubic millimeter.

Physiological Variation in Number. — The number of red corpuscles varies with certain conditions, as follows: 1. The number varies inversely with age, i. e., the greatest number being found in the foetus and gradually decreasing during the life of the individual; 2. the number is decreased in females, being about 4,500,000 per cubic millimeter; 3. the number is decreased after meals; 4. the number is slightly increased during menstruation, and 5. is diminished during pregnancy; 6. the number is increased in those living in high altitudes, and in those going from low to high altitudes the number may be increased to as many as 7,000,000 or 8,000,000 and the change occurs quickly, being noted within a few (twelve to forty-eight) hours. This change seems to occur in answer to a demand of function, there being a call on the system for a greater oxygen-carrying power, due to the lessened amount of oxygen in the air.

The function of erythrocytes is to carry oxygen from the lungs where it is taken from the inspired air, and to carry it to the cells of the various tissues. The oxygen is carried by means of the hemoglobin contained in the corpuscles. Erythrocytes consist of stroma, which is the structural part; certain salts, such as lecithin and cholesterin; water, and hemoglobin, the latter being its chief functional constituent. The hemoglobin constitutes about 32% by weight of the erythrocyte, and 90% of the total solids. It is not known how the hemoglobin is held in the corpuscle, but it is believed to be held in some way by the stroma. Whether the lecithin or cholesterin take any part in the specific functions of the corpuscles is not known. According to Starling the red blood corpuscles constitute about 50% of the total mass of the blood. These small bodies are flexible and elastic, and readily return to their original form when distorted by pressure. The size and shape of the corpuscles vary with different animals. In nearly all mammals they have the shape described above. In vertebrates below the mammals and other animals still lower in the scale of development the red corpuscles are nucleated and biconvex, but normally they have no nuclei in the human. In camels they resemble the human type, but are oval instead of circular. During the first few weeks of fcetal life; after the loss of a quantity of blood by hemorrhage; in certain blood diseases, and before they are passed into the blood stream from their source of formation, the red blood corpuscles of the human may be found to contain nuclei. Nucleated red blood corpuscles or normoblasts are never found in normal blood of the normal human individual after birth. The total surface area of all of the blood corpuscles of the blood is about "1500 times the surface of the body itself'' (Starling). This fact shows the great oxygen -carrying capacity of these corpuscles.

Red blood corpuscles are continually being formed from erythroblasts, the forerunners of the red blood corpuscles contained in the red bone marrow of the epiphyses, and after the development is complete and they have lost their nuclei they are taken up by the blood stream and carried through the circulatory system. In the bone marrow, where the vessels are dilated and the capillaries are very thin-walled, these small bodies may easily enter the vessels. The red bone marrow is the chief and possibly the only hematopoietic (blood-forming) structure in the adult, but the liver and spleen are generally considered as embryonic hematopoietic structures, having to do with the formation of the red blood cells during early embryonic and fcetal life.

Erythrocytes are constantly undergoing degeneration. It is not known how long they exist in the blood stream as functional structures. The products of disintegration as they degenerate are probably taken up and carried away by the leucocytes. In the spleen and in the hemolymph glands certain large phagocytic cells may be found which often contain ingested parts of disintegrated erythrocytes, and it is generally supposed that these structures have something to do with the fate of the useless red blood cells. The hemoglobin of the red corpuscles is taken up by the liver cells and excreted in the bile.

HEMOGLOBIN.

Chemically, hemoglobin is a complex protein consisting of carbon, hydrogen, nitrogen, oxygen, sulphur, and iron. The molecular formula has not been positively determined, but it is known that the molecule is very large. Hemoglobin may be readily broken down by the action of heat or by the addition of alkalis or acids, forming two compounds, hematin and globin, and other undetermined substances. The globin constitutes the greater part of the molecule (about 90%) and the hematin constitutes a much smaller part (about 4%) of the molecule. If hemoglobin be decomposed in the absence of oxygen the products are hemochromogen and globin instead of hematin and globin.

Hemoglobin fo^ms an important constituent of the blood of all vertebrate and many invertebrate animals, and its function, as already stated, is that of carrying oxygen. Hemoglobin constitutes about 14% by weight of human blood, i. e., 100 grams of blood would contain 14 grams of hemoglobin. "It is estimated that in the blood of a man weighing 68 kilograms there are contained about 500 to 700 grams of hemoglobin, which is distributed among some 25,000,000,000,000 of corpuscles, giving a total superficial area of about 3200 square meters." (Howell.) From this statement and the discussion above relative to the surface area of the red corpuscles, it may be seen that a very great area is exposed for the purpose of absorption of oxygen in the lung area and the distribution of oxygen to the tissues.

Hemoglobin Compounds. — In the lungs hemoglobin readily unites with oxygen from the inspired air, forming a definite chemical compound, oxyhemoglobin. This gives to blood its characteristic scarlet color. It may be shown experimentally by passing air through freshly drawn venous blood that the color may be made to change to scarlet. It is probable that each molecule of hemoglobin unites with one molecule of oxygen in the formation of oxyhemoglobin. The compound thus formed is not a stable one, but liberates the oxygen readily when in relation with tissues whose cells are in need of oxygen. The advantage of such a weak combination may readily be seen, for if the oxygen united in such a way as to form a stable compound, the oxygen could not easily be separated for the supply of tissue cells.

With many other substances such as carbon monoxide, oxides of nitrogen, etc., hemoglobin forms stable compounds, one molecule of the hemoglobin uniting with one molecule of carbon monoxide. Because of the formation of this stable compound and because the hemoglobin is thus rendered unable to unite with oxygen for the purpose of carrying it to tissue cells, the carbon monoxide causes asphyxia or suffocation for the lack of oxygen. Asphyxia from gas is due to this cause, the carbon monoxide of the gas rendering the corpuscles unable to carry oxygen.

Iron forms an important constituent of hemoglobin, and while it is present in small quantities (about .33%) this amount is so constant that an estimation of hemoglobin may be made by determining the amount of iron. The function of iron is that of assisting the hemoglobin in combining with oxygen.

Hemoglobin of the blood may be estimated quantitatively by certain instruments (hemoglobinometers), but these are not so practical as the colorimetric method, which is done by comparing the color of a blood stain made by placing a drop of freshly drawn blood upon a piece of absorbent paper and comparing this with certain standard colors, the percentages of which are marked on the scale. The Tallqvist scale is the one most commonly used in clinical work.

Hemoglobin Crystals. — By adding a few drops of ether to freshly drawn blood contained in a test tube and shaking the mixture until the blood is hemolized and then quickly cooling with ice, the crystals may be deposited. The crystals may be observed by placing some of the sediment on a slide and examining with the microscope. Oxyhemoglobin and hemoglobin both readily crystallize and the forms of the crystals are characteristic of the species, i. e., the form, shape, and size of the crystals vary in different animals. The difference in the form of the crystals is probably due to some difference in the molecular arrangement of the hemoglobin of the particular species from which it comes.

Hemolysis. — The process of separation of the hemoglobin from the red corpuscle so that it may pass into solution in the plasma is known as hemolysis. Blood when so changed is known as hemolyzed or laky blood, and substances which have the power of producing a hemolysis are known as hemolytic agents, e. g., bile salts, chloroform, alcohol, ether, various alkaline salts, etc. A great many substances may act as hemolytic agents when brought into the presence of normal blood. Anything which diminishes the osmotic pressure of the plasma, such as the addition of an excess of water, will cause hemolysis. For this reason when it is necessary to inject liquid into the system, a solution of 9% sodium chloride (physiological normal salt solution) is used. It may be that the cause of hemolysis in case of reduction of osmotic pressure by the addition of hypotonic solutions is the comparatively increased pressure within the corpuscle, causing it to rupture and discharge its contained hemoglobin. Whether the above explanation is correct for the cause of hemolysis in case of dilution or reduction of the density of the plasma has not been shown, but that hemolysis may be effected in other ways is evident. There are many toxic substances, such as snake venom, products of bacterial action, or certain contents of. sera of other animals, that may cause hemolysis when injected into the animal or by tests made upon drawn blood in very small quantities, in which case the reduction of the plasma could play no part.