Irritability

“ The strength of the “excitement” depends on the one hand upon the degree of irritability, and on the other upon the strength of the stimulus. The irritability itself is influenced and changed by the action of the stimuli. If the stimuli are too strong and are of prolonged duration, the irritability diminishes as a result of exhaustion; if weak stimuli act during a prolonged time, the irritability increases. The healthy organism has a mean degree of irritability. Disease occurs when this state is altered by strong stimuli or by an absence of stimulation. ”

“ On the contrary, those who are happily possessed of a great degree of irritability, bear labour better than pain; and are strong, active, and ingenious. But there is not properly a temperament of increased irritability tending to disease, because an increased quantity of irritative motions generally induces an increase of pleasure or pain, as in intoxication, or inflammation; and then the new motions are the immediate consequences of increased sensation, not of increased irritation; which have hence been so perpetually confounded with each other.
II. Temperament of Sensibility. ”

“ Now nothing can so strongly evince that this quick small pulse is owing to defect of irritability, than that an additional stimulus, above what is natural, makes it become slower and larger immediately: for what is meant by a defect of irritability, but that the arteries and heart are not excited into their usual exertions by their usual quantity of stimulus? but if you increase the quantity of stimulus, and they immediately act with their usual energy, this proves their previous want of their natural degree of irritability. ”

“ The irritability of the living system can, therefore, not be studied alone, but as the properties of a living system are dependent upon each other, so this property must be considered with the others possessed by a living substance. ”

“ These three factors, irritability, intensity and velocity of the progress of the wave of excitation, are inseparable. All living substances may be grouped according to their capability of conducting137 excitation into a long series, starting with those possessing the least irritability, as we found in the rhizopods, then those having greater irritability, as the smooth muscle and ganglion cells, then those with still greater irritability, as the striped muscle, and finally those having the greatest degree of irritability, as the medullated nerves of the warm-blooded animal. ”

“ These alterations of the specific irritability following an excitation and their compensation through the metabolic self-regulation will now claim our attention.
That the specific irritability of a living system undergoes a diminution as the result of a stimulus of long duration has been long known through the study of fatigue. This is especially so with frequently recurring excitating stimuli. ”

“ I refer to a most important fact in the general physiology of irritability. Irritability of any kind is known to be re-established, after it has been disturbed by the process of reacting to the stimulus, and in certain cases, in which two different—or rather two opposite—kinds of reactions are possible on the same substratum, which increase with regard to one process whilst decreasing at the same time with regard to the other. ”

“ The irritability of the whole, or of part, of our system is perpetually changing; these vicissitudes of irritability and of inirritability are believed to depend on the accumulation or exhaustion of the sensorial power, as their proximate cause; and on the difference of the present stimulus, and of that which we had previously been accustomed to, as their remote cause. Thus a smaller degree of heat produces pain and inflammation in our hands, after they have been for a time immersed in snow ”

“ If a living organism is the subject of consideration, to which the “all or none law” is applicable, as, for instance, the heart at the moment of the beginning of excitation, irritability is completely obliterated, as shown by the fact that the second stimulus of any strength remains without response, for during the excitation there is a complete breaking down of all the substances capable of decomposition. ”

“ Persons suffering under frequent fever, or certain kinds of pain or nervous disturbance, or afflicted with ill-qualified nurses, may be pardoned for almost any degree of irritability, or may be unspeakably meritorious in resisting the tendency, with more or less steadiness. But there are some of us who cannot but smile at compliments on our freedom from irritability, when we feel that we never have the slightest inclination to be cross, nor have the least excuse for being so,—while we may be most abasingly aware of other kinds of frailty of temper. ”

“ It is self-evident that irritability must again increase in the same degree as the restitution of the living system by metabolic self-regulation takes place, for the more molecules capable of disintegrating are restored and the more products of disintegration removed, the more molecules necessary for decomposition in the unit of space are attacked and broken down by the stimulus. ”

“ The passions are all serious for health when permitted to get beyond bounds. Many a case of indigestion is dependent on that irritability of temper which so often develops in good feeders and then proceeds to form a vicious circle of influence, perpetuating itself. Irritability of tissues is often in direct ratio to irritability of temper, and not a few men owe both conditions to overindulgence in the pleasures of the table and failure to acquire, to some extent at least, such habits of self-control as the practice of fasting at intervals would help them to secure. ”

“ With every change, therefore, of organic form or addition of organic parts, I suppose a new kind of irritability or of sensibility to be produced; such varieties of irritability or of sensibility exist in our adult state in the glands; every one of which is furnished with an irritability or a taste or appetency, and a consequent mode of action peculiar to itself. ”

“ There are very many causes for irritability, and we each have our own individual sensitiveness or antipathy, but, whatever the secondary cause, the primary cause is always the same,—resistance or unwillingness to accept our circumstances. ”

“ Until quite recently all those effects of external factors on the living substance which consist in excitation, that is, in an increase of their specific vital processes, have always stood in the foreground of all researches and observations on irritability. It was gradually, however, more and more recognized that the depressing influence of stimuli played a great rôle in the vital process of the organism. ”

“ We all know that a morbid condition irritates the individual and excites sarcastic and disagreeable remarks. And, likewise, an irritable temper and, suddenly aroused passions may not only turn and disturb the stomach, but even poison the secretions. Anxiety, excitability, fear, and irritability frequently cause the perversion of physiological processes.
The slightest functional disturbance of the stomach deranges, more or less, all the succeeding operations of digestion and tends to the vitiation and impairment of the delicate processes of nutrition. ”

“ For perception in any subject is vain, unless it can desire, and appetence is useless, unless it can move. External sensibility, therefore, may be said to render the fibres actu irritabiles, for example, as often as the irritating cause is perceived; but as the irritation is perceived, not by a sensibility, but by a mere natural perception, this it is which constitutes their irritability.
Thus we may perceive that the triunit consisting of perception, appetence, and motion, constitutes the celebrated irritability of our author. ”

“ We know that when a person is in a faint he is insensible to ordinary stimuli, though very strong ones will rouse him; but what can we infer from this? Nothing; only we see it is so. Does it avail us any thing to be told that during the time of fainting the irritability is exhausted, and “in a short time the irritable principle will accumulate afresh;” in which case the patient will no doubt recover, unless he happens to be dead, which is the true meaning of an irreparable exhaustion of the irritability. ”

“ In TREATMENT irritability, restlessness, absence of a power and sense of responsibility, and sleepless, excitable nights, are the most difficult symptoms to combat. The restlessness and irritability often lead to refusal to be reasonably controlled and to a tendency to wander away from home with theatrical displays, so as, in the case of girls particularly, to require restraint, especially if the excitability should be so great as to amount to outbursts of violence or should lead to sexual improprieties. ”

“ When the sum of the stimuli, acting on the body, is so small, as not to carry off the excess of excitability, it accumulates, and diseases of irritability are produced. Of this nature are those diseases to which the poor are often subject, and which will be particularly considered hereafter. ”

“ To the thinkers both in the field of physiology and medicine of ancient and mediæval times the conception of irritability was quite foreign. Even a comprehension of the nature of stimuli had not yet begun to crystallize from vague impressions of the various influences of different agents on the human being. Nevertheless they knew of such influences of the most varying kinds upon the human body. The ancients already possessed a materia medica, founded on the real or supposed influence of various mineral, vegetable and animal substances upon the organism. ”

“ I will content myself so far with saying what may be said for everything that can bless and curse mankind, that in moderation it is at least harmless; but what is moderate and what is not, must be determined in each individual case, according to the habits and constitution of the subjects. If it cures asthma, it may destroy digestion; if it soothes the nerves, it may, in excess, produce a chronic irritability. ”

“ Stomach irritation is expressed largely through the mind, as in irritability, nervousness and melancholia, while intestinal irritation is generally expressed by some physical symptom, such as restlessness, twitching of the muscles and a general lack of physical tranquillity. ”

“ When we talk of life we mean vital activity. Now, every vital action supposes an excitation or irritation. The irritability of the part is the criterion by which we judge whether it be alive or not. Our notion of the death of a part is based upon nothing more or less than this—that we can no longer detect any irritability in it. ”

“ If we first turn our attention to the normal refractory period which occurs in a system in metabolic equilibrium of rest in direct connection with dissimilatory excitation, following a momentary stimulus, we find that reduction of irritability or, more exactly expressed, the lessening of the response is, as we have seen, determined by the time involved in the metabolic decomposition and recovery. ”

“ As the stomach by their violent stimulus at length loses its natural degree of irritability, and indigestion is the consequence; which is attended with flatulency and emaciation. Where any of these have been taken so long as to induce a habit, they must either be continued, but not increased ”

“ But if the increase of irritability, and the consequent increase of the stimulus of heat and momentum, produce more violent exertions than those above described; great pain arises in some part of the moving system, as in the membranes of the brain, pleura, or joints; and new motions of the vessels are produced in consequence of this pain, which are called inflammation ”

“ The loss of self-control, reacting upon the body, produces a morbid irritability (always a sign of weakness) which is a real disease, subjecting the individual to constant excitement and exhaustion from slight causes. ”

“ I. The temperament of decreased irritability known by weak pulse, large pupils of the eyes, cold extremities. Are generally supposed to be too irritable. Bear pain better than labour. Natives of North-America contrasted with those upon the coast of Africa. Narrow and broad shouldered people. Irritable constitutions bear labour better than pain. ”

“ No muscle, or other part, removed from the body, long preserves its irritability. This power cannot subsist permanently, except in connexion with an organic whole. This condition peculiarly constitutes irritability a living force: and this condition would be satisfied by considering the force as derived from the nervous system; but it appears that though the nervous system has the most important influence upon all vital actions, the muscular irritability must needs be considered as something distinct. ”

“ Yet even in instances of this kind, a close examination will often detect, that the irritability, which has been attributed to the author’s genius as its cause, did really originate in an ill conformation of body, obtuse pain, or constitutional defect of pleasurable sensation. What is charged to the author, belongs to the man, who would probably have been still more impatient, but for the humanizing influences of the very pursuit, which yet bears the blame of his irritability. ”