Physiological reaction

“ If we suppose a living system in a state of metabolism of rest influenced by an instantaneously excitating stimulus, the entire course of excitation extends from the first alteration produced by the stimulation until the complete restitution of the metabolic equilibrium, and we will, therefore, differentiate individually the successive stages of this whole process. ”

“ Alterations in those factors which act as vital conditions compose the great mass of physiological stimuli which act continuously on every living organism. The first point to be considered in every alteration is its direction. The alterations produced by stimuli may be of two different kinds, either positive or negative. The quantity of foodstuffs, water or oxygen, in the surrounding medium, can undergo an increase or diminution; as may the temperature, intensity of light, the atmospheric and osmotic pressure. The strength of the electric current, which may be applied, can also be regulated. ”

“ It is sufficient for our purposes to know that they may have set up certain internal stimuli which may modify the behavior of the organism in which they reside, and that the “physiological state” of the organism at the time of external or internal stimulation will condition the response. This physiological condition may be dependent on the general metabolic equilibrium of the animal, or on the extent of previous stimulation by means of the same or different agents. Thus the organism may not always react in the same way to the same stimulus. ”

“ It remains for us to obtain data concerning the cycle of excitation processes in the living substances by the aid89 of the combined employment of the most varied kinds of physical as well as chemical indicators. If we use the most varied types of living substance of widely differing properties, showing us the greatest variety of vital manifestations, we may hope by the use of comparative physiological methods, even though with difficulty, to separate more and more the essential details of the general processes of excitation. ”

“ Every one knows that the living muscle and nerve, when in repose, present an alkaline or faintly neutral reaction, and after excitation this is changed into an acid reaction, which increases with the exhaustion of the tissue. ”

“ All the experiments in physiology consist practically in the production of so many pathological conditions and states. When the physiologist makes injections, sections and stimulations by various agencies, what else does he effect if not the production of the pathological, in order to learn the physiological action of the various tissues and organs? ”

“ If it is asked, which members of the entire metabolic chain are increased primarily by the stimulating excitation of a vital system, we should not be able to answer this question generally for all living systems. ”

“ It is an accepted physiological law that nothing taken as food or drink can support expenditure of human energy in sensible motion, in heat, or in the nervous waste of mental or emotional exercise without first being built up into living tissue; the breaking down or chemical decomposition of which tissue, and subsequent oxidation of less complex compounds or their constituents, is the direct source of bodily energy of every description. ”

“ There are three kinds of stimulus, which may easily be occasionally diminished, that of heat on the skin, of food in the stomach, and of the oxygenous part of the atmosphere, which mixes with the blood in respiration, and stimulates the heart and arteries. ”

“ In these instances, the influence of the stimulus directs the metabolism of rest into new channels, so that chemical processes occur in the cell, which under ordinary circumstances do not take place. This group of reactions, which I wish to term “metamorphic stimulation and response,” are chiefly observed where weak stimuli act continuously upon the living substance. These are essentially weak chemical stimuli, which last for a prolonged period or frequently reoccur in the life of the cell community. ”

“ Every act of volition, every exertion of muscular power, every functional action of the organism, whether perceptible or imperceptible and involuntary, every play of chemical affinity and decomposition, even thought itself, occasions the disorganisation and destruction, as living matter, of a portion of ourselves. But the process of respiration, and the various important changes with which it is connected, tends, more than all the other vital functions, to waste the substance of the body, the temperature of which it is its special office to support. ”

“ The reactions to catalytic stimuli of short duration, which produce merely an alteration of rapidity in the specific phenomena of a living organism, show on a closer analysis the interesting fact, that it is not always the entire metabolic processes of the cell which are perceptibly quickened, but that only certain constituent processes of the same are affected by the action of excitation. ”

“ In this, but only in this sense, can these two conceptions be placed in opposition and used to characterize the processes in the living organism. The conception of the metabolism of stimulation must always stand in relation to that of an equilibrium of metabolism characterized by a constantly existing metabolism of rest, just as the conception of stimulus can likewise only be defined relatively to that of vital conditions. ”

“ The result of excitation, or if one will, of stimulation of a living part, can, therefore, according to circumstances, be either merely a functional process, or there can be a more or less intense nutritive activity produced without the function being necessarily at the same time activated, or finally, it is possible11 that a process of formative change may occur which produces new elements in greater or less numbers. ”

“ The molecules of these residual tissues which form the storehouse of energy in the body are rearranged in simpler forms, thereby giving up a portion of the energy which holds them together in the state in which they exist in the tissues, and this energy thus set free appears as muscle force, mental activity, glandular work and various other forms of functional activity. ”

“ The physiological independence of organs, together with their intimate dependence in the organism, and the fact that this organism is incessantly stimulated from many sides at once, assure us a priori that the “waves” of molecular movement due to each stimulus must sometimes interfere and sometimes blend with others, thus diverting or neutralizing the final discharge in the one case, and in the other case swelling the current and increasing the energy of the discharge. We are accustomed to speak of one part “playing on another,” sympathizing with another, and so on ”

“ For the first time in the history of science, physiologists are now in the position to say that they have arrived at clear and distinct, though by no means complete, conceptions of the manner in which the great functions of assimilation, respiration, secretion, distribution of nutriment, removal of waste products, motion, sensation, and reproduction are performed ”

“ This is explained from the physiological point of view by saying that internal and external stimulation—internal from the digestive organs and system in need of food, external through the eye—gives rise to a state of unstable equilibrium in the nerve-centres; and that, when the instability reaches a certain value, the nervous system discharges into the motor organs, the chick pecks, and stable equilibrium is restored. The tendency to discharge in some way under stimulation is an essential characteristic of a nervous system. It is one of the facts of physiological science. ”

“ The natural sciences, if they are to retain their reputation for exactness and precision, require the strictest and clearest definitions of all conceptions. If we seek to penetrate more deeply into the varied happenings in concrete conditions, we must reconcile71 ourselves to dry pedantic definitions. In the case of that of the equilibrium of metabolism indeed we have before us one of the most important conceptions in physiology. ”

“ But if we consider this great function in the important relations of nutrition, secretions, exhalations, for which they furnish the materials, of the general stimulus it carries to all parts, and which is indispensable to the support of life, of the introduction of foreign fluids in the body of the animal, and of the change of these fluids into its own substance ”

“ The combination of the different varieties of these single factors, that is, the nature, the direction, the intensity, the rapidity, the duration and number of alterations in the external vital conditions of the organism produce the enormous variety of effects of stimulation which we observe in the living world. ”

“ The products formed in this process influence the contraction of the muscles—mostly indirectly, through the central nervous system. If the animal is illuminated on one side only the mass of photochemical reaction products formed on that side in the unit of time is greater than on the opposite side. ”

“ We come now to the supreme and all-pervading metabolism which has for its effects the conspicuous manifestations of life—the nervous and muscular activities. Here comes up afresh a question discussed in the edition of 1864—a question to be reconsidered in the light of recent knowledge—the question what particular metabolic changes are they by which in muscle the energy existing under the form of molecular motion is transformed into the energy manifested as molar motion? ”

“ For we must look at the organism as a store of energy which is used up in the course of the adjustments of the individual to his environment. The organism stores up energy and uses the energy during the course of its life activity.
Life energy is physiological, bio-chemical, electrical, mechanical, etc. The mental and emotional activities are intimately related with the expenditure of energy accumulated by the cells of the organism, which discharge that energy in response to the various stimulations of the external world. ”

“ Just as the conceptual activity has as its bodily foundation the brain, with the nervous appendages, so it is volitional activity which is based on processes taking place in the muscular region of the body and in those organs which provide the body's metabolism. ”

“ If excitations weaker than natural be applied, so as not to excite the organ into action, (as when small doses of aloe or rhubarb are exhibited,) they may be gradually increased, without exciting the organ into action; which will thus acquire a habit of disobedience to the stimulus ”

“ The blood-vascular and respiratory and excretory systems have become well organized, in response, so to speak, to the demands on the part of the nervous and alimentary organs that they may be relieved of the tasks of circulation and respiration and the discharge of ash-wastes. ”

“ Dr. James Mark Baldwin, Stuart Professor of Psychology in Princeton University, U.S.A., called attention early in the 90’s to a reaction characteristic of all living beings, which he terms the “Circular Reaction.” We take his most recent account of this from his “Development and Evolution” (1902) :— [0h]
“The general fact is that the organism reacts by concentration upon the locality stimulated for the continuance of the conditions, movements, stimulations, which are vitally beneficial, and for the cessation of the conditions, movements, stimulations which are vitally depressing.” ”

“ When these nervous impulses reach the central nervous system in ordinary circumstances they do not give rise to changes that reach the level of consciousness, but they form, as it were, the warp and woof of our mental life, and they also affect metabolisms, that is to say, nutritive changes in many parts of the body. ”

“ When we come to consider more in detail the results of these actions we find that the various secretions of the body, such as the sweat, gastric juice, bile, milk, urine, &c., may be increased or diminished; that the heart may have its muscular or nervous apparatus stimulated or depressed; that the nerve-centres in the brain, medulla and spinal cord may be rendered more sensitive or the reverse; and that the general metabolism of the body may be altered in various ways. ”

“ The reaction we have demonstrated enables us at any time to decide whether a certain substance is in harmony with the body or not. We have already emphasized the fact that we must distinguish not only substances that are in, or out of, harmony with the body, but also those which are in, or out of, harmony with the blood or its plasma, or again with the cells. ”

“ By the stimulus of wine or opium the whole arterial system, as well as every other part of the moving system, is excited into increased action. All the secretions, and with them the production of sensorial power itself in the brain, seem to be for a time increased, with an additional quantity of heat, and of pleasureable sensation. ”

“ The affinity which is involved in metabolism must be the choice of the particles themselves, in obedience to commands issued by the organism of unicellular particles of which the body is composed, these ultimately acting in obedience to the command of the cortical consciousness. ”

“ So that this excessively unstable compound, decomposing in the body in a very short time, produces within that short time a vast amount of molecular change: acting, as it seems, not through the nervous system, but directly on the blood-vessels. ”

“ Even a very meagre knowledge of the structure and action of our bodies is enough to reveal the following distinctive characters: our bodies are continually breathing, that is, they take in oxygen from the surrounding air; they take in certain substances known as food, similar to those composing the body, which are capable through a process called oxidation, or through other chemical changes, of setting free a certain amount of energy. ”

“ In accordance with the three groups into which general vital phenomena are divided, it follows as a matter of course that the excitation or depression produced by a stimulus can manifest itself in the cell's metabolism, assumption of form, and manifestation of energy. The effects of excitation upon the production of energy are the most striking, and were therefore in former times frequently thought to have a claim par excellence to rank as stimulating effects. ”