Vasomotor system

“ The quantity of blood in any part of the body at any given time is dependent upon certain relations which exist between the blood-vessels and the nervous system. The walls of the arteries are abundantly supplied with involuntary muscular fibres, which have the power of contraction and relaxation. This power of contraction and relaxation is controlled by certain nerves called vasomotor nerves, because they cause or control motion in the vessels to which they are attached. ”

“ Facility of motor discharge. Great concentration was necessary of course, but not sufficient. Persons in whom the flow of nervous energy tended to drain off over the nerves leading to the glands and the vascular system might betray great tension, not so much by movements as by a flow of perspiration (we have many excellent examples of this given by Manouvrier) [93] or by a violent beating of the heart, blushing and the like,—in short, by secretory and vasomotor effects. ”

“ Our higher faculties appear to be related, not only to the brain, but to the sympathetic nervous system, having to do with the vaso-motor apparatus. The facts have been established that it is only in connection with exercise that the whole circulatory apparatus, as well as the vaso-motor system, comes to its full development. The balanced distribution of the blood to the body is definitely related to the power and regularity of the heart, and to that vaso-motor education that comes in connection with varied muscular contraction. ”

“ The right side of the heart soon becomes incapable of driving the unoxidized blood through the lungs; the left ventricle at first readily propels the blood into the lax arteries, but soon the supply is diminished and the contraction becomes feeble, and at the same time the blood is accumulating in the venous system, and thus tending to equalize the pressure, and so at last the left ventricle is unable to drive its modicum of blood through the systemic capillaries. ”

“ This circulation is maintained by means of a pumping organ or heart, which receives the blood from the veins and by the contraction of its powerful walls forces this into the arteries, the direction of flow being determined as in a pump, by a system of valves. The waste products of cell life pass from the cells into the fluid about them, and are in part directly returned into the blood, but for the greater part pass into it indirectly through another set of vessels, the lymphatics. ”

“ With the Production of new Vessels by internal Membranes or Glands, without Fever.
Where inflammation is produced in a small part, which has not great natural sensibility, the additional sensation does not produce an increased action of the arterial system; that is, the associated motions which are employed in the circulation of the blood, those for instance of the heart, arteries, glands, capillaries, and their correspondent veins, are not thrown into increased action by so small an addition of the sensorial power of sensation. ”

“ Johannes Müller, the foremost physiologist in Germany, in his classical work on physiology in 1838, concluded that the arteries did not possess a muscular coat but only physical elasticity. He was entirely unprepared for the idea of vasomotor nerves. The sympathetic nerves had been traced to the blood vessels and some thought they should have something to do with the circulation. Stilling introduced the word "vasomotor" in arguing from theoretical grounds that the circulation must be governed by nerves not subject to the will, but influenced by sensory stimuli. ”

“ It is a mistake to try to scramble to one’s feet immediately, because until the vasoconstrictor center recovers its ordinary activity, raising of the head above the level of the rest of the body is bound to result in its failure to receive sufficient blood, and so faintness will come on again. It has long been a practice to dash cold water in the face of a fainting person. The physiological value of this is in the sudden stimulation of the sensory nerves in the face by which is set up a stream of nervous discharges which will play upon the vasomotor center, and arouse it again to activity. ”

“ Normally, the sum of the resistances which at any moment opposes the outflow through the capillaries is maintained at the same value, for the vascular system is so coordinated by the nervous system that dilatation of the arterioles in any one organ is compensated for by constriction in another. Thus the arterial pressure remains constant, except at times of great activity. ”

“ On the due discharge of the respiratory function, too, the function of circulation is directly dependent: if the aeration of the blood is impeded the vascular activity is lowered; and arrest of the one very soon causes stoppage of the other. Similarly with the duties of the nervo-muscular system. Animals of low organization, in which the differentiation and integration of the vital actions have not been carried far, will move about for a considerable time after being eviscerated, or deprived of those appliances by which energy is accumulated and transferred. ”

“ By compressing the abdomen to fill the heart, and then compressing the thorax to empty it, the valves meanwhile directing the flow, a pressure of blood can be maintained in the aorta even when the heart has ceased to beat, and this if patiently continued may lead to renewal of the heart-beat. There is no certain evidence that the pulmonary arteries are controlled by vaso-motor nerves. In the intact animal it is difficult to determine whether a rise of pressure in the pulmonary artery is induced really by constriction of the pulmonary system, or by changes in the output of the heart ”

“ Blake; who found that many substances, soon after they are injected backwards by the axillary artery into the aorta, produce increased pressure in the arterial system indicated by the hæmadynamometer during life, and frequently congestion of the membranous textures as observed after death. Some substances have no effect of this kind. Others act on the general capillaries in concurrence with a similar action on the capillaries of the pulmonary circulation, such as the salts of strontia, baryta, lead, silver, and soda, euphorbium, tobacco and digitalis. ”

“ It is almost impossible to exaggerate the importance of these labours of Bernard on the vaso-motor nerves, since it is almost impossible to exaggerate the influence which our knowledge of the vaso-motor system, springing as it does from Bernard's researches as from its fount and origin, has exerted, is exerting, and in widening measure will continue to exert, on all our physiological and pathological conceptions, on medical practice, and on the conduct of human life. ”

“ The whole bulk of their blood is arterial, if we may use the expression in speaking of animals which do not possess a vascular system. In other words, being incessantly vivified throughout the body, owing to the comprehensive character of the respiratory apparatus, no portion of it becomes at any time effete from the exhaustion of the contained oxygen. ”

“ The venous side of the vascular system, owing to the great size of the veins, has a large potential capacity, while many of the capillaries in each organ are empty and collapsed, except at those periods of vaso-dilatation and hyperaemia which accompany extreme activity of function. The vascular system cannot be regarded as a closed system, for the blood-plasma, , whenever the capillary pressure is increased, transudes through the capillar wallinto the tissuesgaces and enters the lymphatics. ”

“ We have in our bodies a system of canals called arteries and veins, having their head at the heart, which is the main pump that keeps the blood in motion. The arterial circulation consists of those channels which convey the blood—supposed pure blood—away from the heart to the different parts of the body, loaded with the life-giving principle of sustenance, invigoration and heat, while the veins or venous circulation conveys to the heart and lungs the impure blood, loaded many times with disease-breeding germs. ”

“ The vascular system itself is quite peculiar, consisting of lacunae and channels destitute of endothelium, situated within the thickness of the basement-membrane of the body-wall, of the gut-wall and of the mesenteries. The blood, which is a non-corpuscular fluid, is propelled forwards by the contractile dorsal vessel and collected into the central blood-sinus; this lies over the stomochord, and is surrounded on three sides by a closed vesicle, with contractile walls, called the pericardium (Herzblase) . ”

“ At birth, when the internal motions become suddenly very numerous, on account of respiration, digestion and the excretions, I presume that the serous surfaces become the seat of a more active exhalation. Besides, as very little blood penetrates them, the sudden production of the red blood and its entrance by the arterial system, where it succeeds the black blood, produces less changes upon them than upon the mucous surfaces and the muscular system. ”

“ Vide Pereira's Materia Medica, vol. i. pp. 101, 106.
[23] Such is the case in health, when the muscular pressure of the intestine must exceed the pressure on the vascular system on the other side. This latter pressure, when increased, tends to stop or to reverse the inward current. Thus plethora and fever, diseased conditions, counteract absorption by causing pressure on the coats of these capillary vessels. ”

“ What makes it more probable that the arterial system is materially affected in the consumption is, that the disease most frequently occurs in those periods of life, and in those habits in which a peculiar state of irritability or excitability is supposed to be present in the arterial system ”

“ The quick and laborious breathing of running people, who are not accustomed to violent exercise, is occasioned by the too great conflux of blood to the lungs. As the sanguiferous system, as well as the absorbent system, is furnished in many parts of its course with valves, which in general prevent the retrograde movement of their contained fluids ”

“ Hg-while the vascular system of the rest of the body bears the full atmospheric pressure. The thin walled auricles and veins yield more to this elastic traction than the thick-walled ventricles and arteries. Thus inspiration exerts a suction action, which furthers the filling of the veins and auricles. This action is assisted by the positive pressure exerted by the descending diaphragm on the contents of the abdomen. Blood is thus both pushed and sucked into the heart in increased amount during inspiration. ”

“ When there is a sudden rise in the blood-pressure in the arteries, due to vasomotor spasm of the peripheral systemic arterioles, and the heart-walls are strong and well nourished, palpitation is evoked; when the coronary branches are involved in the vasomotor spasm then angina is produced, and the heart-walls, acutely distended with blood, can scarcely contract in the face of the opposition presented to their contraction by the high arterial tension. ”

“ When diffused in the air, these noxious particles are conveyed into the system through the thin and delicate walls of the air vesicles of the lungs in the act of respiration. The mode in which the air vesicles are formed and disposed is such as to give to the human lungs an almost incredible extent of absorbing surface, while at every point of this surface there is a vascular tube ready to receive any substance imbibed by it and to carry it at once into the current of the circulation. ”

“ One system supplies the kidney substance with nourishment in the form of nutrient blood; the second system supplies the glomerules with what may be considered functional blood (Gadow) . The second system of arteries branches into the small arteria interlobularis, which pass between the lobules of the kidneys where they give off side branches which penetrate the cortical portion of the lobules and form the capillary plexus, the glomerule. ”

“ There is hardly a physiological discussion of any width in which we do not sooner or later come on vaso-motor questions. Whatever part of physiology we touch, be it the work done by 59 a muscle, be it the various kinds of secretive labour, be it the insurance of the brain's well-being in the midst of the hydrostatic vicissitudes to which the changes of daily life subject it, be it that maintenance of bodily temperature which is a condition of the body's activity; in all these, as in many other things, we find vaso-motor factors intervening. ”

“ And if, passing the insecure and wavering line which parts health from illness, we find ourselves dealing with inflammation, or with fever, or with any of the disordered physiological processes which constitute disease, we shall find, whatever be the tissue specially affected by the morbid conditions, that vaso-motor influences have to be taken into account. The idea of vaso-motor action is woven as a dominant thread into all the physiological and pathological doctrines of to-day ”