Blood circulation

“ The only way in which an increased blood supply can be obtained is by causing the blood to flow more rapidly. This is precisely what happens every time the blood pressure in the body rises. Whenever the vasoconstrictor center sends nervous discharges into the blood vessels of the skin and abdominal organs, causing them to contract, there is a diversion of blood from them directly into the skeletal muscles and also a rise in blood pressure due to the increase in resistance to the circulation, which causes blood to flow more rapidly through the brain. ”

“ It will be always a difficult thing to prove, that the secretions, the exhalations, and the process of nutrition, could not be made from venous blood, because the circulation of this sort of blood in the arteries, does not continue for a sufficient time, to allow of observations, or the manner in which these functions would be affected by it. ”

“ But this deficiency of arterial blood may be depending on a more positive cause, venous congestion, impeding its flow; for in sleep, the breathing being slower, the blood becomes essentially darker. Even arterial blood itself will become to a certain degree carbonized, by lentor, or stagnation. Venous congestion and diminution of arterial circulation are not incompatible ”

“ It is in this sense that the heart, so remarkable for its cavities, should be reckoned a workshop, source, perpetual fire-place; it is like a hot kettle by virtue, not of its body, but of its contained blood, in the same sense in which the liver, the spleen, the lungs, and other parts are reckoned hot; because they contain many veins or vessels containing blood. In this way also I maintain that the native heat, or innate warmth, being the common instrument of all the functions, is likewise the prime efficient cause of the pulse. ”

“ But I trust that we have facts enough to establish it as a certainty, 1st, That the black blood after the interruption of the chemical functions of the lungs, continues for some time to circulate, and 2dly, That it penetrates into the organs, where it replaces the red blood; these circumstances explain the reason, why on opening the body we always meet with black blood even in the vessels which are destined for the circulation of arterial blood. ”

“ 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. ”

“ For the present be it enough to have shown sufficiently that during the beat of the heart the blood is transfused and withdrawn from the veins into the arteries through the ventricles of the heart, and is distributed to the body at large. ”

“ The blood vessels hold the blood, supply the channels and force necessary for its circulation, and provide conditions which enable materials both to enter and to leave the blood stream. The heart is the chief factor in propelling the blood, although the muscles and the elastic tissue in the walls of the arteries and the valves in the veins are necessary aids in the process. In the capillaries the blood takes on and gives off materials, while the arteries and veins serve chiefly as tubes for conveying the blood from one system of capillaries to another. ”

“ When this obstruction of the circulation by uric or carbonic acid prevails throughout the body, the blood pressure is too high in the arterial blood vessels and in the interior organs, such as heart, lungs, brain, etc., and too low in the surface, the extremities and in the venous circulation. The return flow of the blood to the heart through the veins is sluggish and stagnant because the force from behind, that is, the arterial blood pressure, is obstructed by the uric acid which clogs the minute capillaries that form the connection between the arterial and the venous systems. ”

“ Since the circulation, no less than the breathing, is concerned in the supply of oxygen to and removal of carbon dioxide from the tissues, it can readily be understood that defective circulation, such as occurs, for instance, in uncompensated valvular affections of the heart, may affect the breathing and hinder the normal respiratory exchange. Conversely, also, defects in the aeration or oxygen-carrying power of the blood may be compensated for by increase in the circulation. ”

“ But it is necessary that the heart shall be assisted considerably, in the circulation 357 of the blood, by a contractile power of the vessels themselves; and the same quantity of blood is not to circulate in the same body at all times, for animals are liable to frequent injuries, by which the quantities of blood in their bodies may be very suddenly reduced. ”

“ But such experiments are not applicable to the blood. Though that of the arteries may be somewhat hotter than the venous blood, yet the reason is obvious. The heat is communicated directly to the arterial blood in the lungs; but during the circulation a part of it evaporates, and the farther distant any part is from the lungs, the more cool will the vital fluid be, without regard to any alteration of capacity, which indeed never can be shown to exist. ”

“ After injury the dilatation of the vessels with the greater afflux of blood to the part is the effect of the greatly increased cell activity, and is a necessity for this. In many forms of disease it has been found that by increasing the blood flow to a part and producing an active circulation in it, that recovery more readily takes place and many of the procedures which have been found useful in inflammation, such as hot applications, act by increasing the blood flow. ”

“ No condition can be properly treated, no operation should be performed, and no prognosis is of value without a proper consideration of the sufficiency of the circulation, and the condition of the circulation cannot be properly estimated without an accurate estimate of the systolic and diastolic blood pressure. However perfectly the heart may act, it cannot properly circulate the blood without a normal tone of the blood vessels, both arteries and veins. ”

“ Among the researches of the last thirty years, those bearing on the Circulation of the Blood must take an important place, both for their physiological interest and for the weighty influence they have exerted on our knowledge and treatment of disorders of the vascular system, such as heart disease. ”

“ One would naturally suppose that the circulation in the larger arteries would, in this manner, be interrupted, and such is the case. But, herein comes an additional advantage to aid the circulation, for the temporary and momentary intermittent compression causes a dilatation of the artery from an increased volume of blood above the part pressed upon, and this accumulation rushes onward with greater rapidity as soon as the pressure is removed, in consequence of the force of the heart's action and the resiliency of the arteries acting upon the accumulated volume of blood. ”

“ In the sanguine temperament all the vital functions are more active, the blood itself has a deeper hue, its corpuscles carry more oxygen, the complexion is quite florid, and the arterial currents impart to every faculty a more hopeful vigor. The blood-vessels are the most active absorbents, eagerly appropriating nutritive materials for the general circulation, while the respiration adds to it oxygen, that agent which makes vital manifestation possible. ”

“ The great majority presented distinct thickening of the arterial walls. As I suggested in our study of the etiology, these pathological changes appear to be the result of malnutrition of structures (the myocardium, valves and arteries) worked at high pressure; and in addition to the local disturbance of metabolism in the cardiac and arterial walls, which are fed with gouty blood, there is the damaging effect on them of similar disease of the vasa vasorum and vasa cordis or coronaries. ”

“ Such persons as a rule are not long-lived, inasmuch as their power of resistance is small, owing to their lack of blood, a lack in quality as well as in quantity. The blood pressure in their arteries and veins is light, as evidenced by their pale, sallow complexion, and the dry, scaly, feverish skin, which seldom or never perspires. ”

“ There is no pulse, because there is no blood in the arteries." "There are also lethargy and languor, and oppression in breathing, caused by the blood being collected in the veins. These make up the principal links in the chain of mechanical symptoms." ”

“ The arterial tissue is no exception to this rule, and we have already shown that certain changes normally take place as the individual grows older, changes which are arteriosclerotic in type and are quite like those caused in younger people by many of the etiologic factors of the disease.
We are absolutely dependent upon the integrity of our hearts and blood vessels for the maintenance of activity and span of life. Respiration may cease and be carried on artificially for many hours while the heart continues to beat. ”

“ A sufficiency of blood to distend it collects within the venous cistern. The arterial system, owin to its elasticity and contractility, empties. If the heart now begin to beat, blood is taken from the venous system and is driven into the arterial system., The arteries receive more blood than can escape through the capillary vessels, and the arterial side of the system becomes distended, until equilibrium is reached, and as much blood escapes into the venous side per unit of time as is delivered by the heart. ”