Bloodstream

“ The blood cells are important members of the cell-community, and are exceedingly numerous, there being over 75,000,000,000 of the red-blood cells alone. These red-blood cells move in the blood currents, carrying through the arteries each its little load of oxygen which it transports to the distant tissues that they may be invigorated and vitalized anew; and, returning, carrying through the veins the debris and waste products of the system to the great crematory of the lungs where the waste is burnt and thrown off from the body. ”

“ The blood is a fluid akin to the lymph, but confined in a system of tubes. Through these tubes it is driven at a considerable velocity, and in the course it takes passes within a reasonable distance of every cell in the body. As it passes the cells of the alimentary canal, they discharge the nutriment they have absorbed into it; as it passes through the other organs of the body, it discharges the requisite materials into the lymph bathing the actual cells: these are then able to help themselves. ”

“ The Lymphatic System.—In addition to blood-vessels, Fishes possess a lymphatic system, consisting of smaller vessels, lymph-capillaries or lymph-spaces, distributed in the connective tissue of different parts of the body, and by their union ultimately forming larger lymph-vessels or sinuses which communicate with certain of the principal veins, the whole forming a series of channels for the collection of the blood-plasma which has exuded from the blood-capillaries for the nutrition of the tissues, and for its conveyance to the general venous system. ”

“ When freighted with oxygen it becomes oxyhaemoglobin and is red in color; when freed from its oxygen it takes a purple hue; hence the widely different appearance of arterial and venous blood, which so puzzled the early physiologists.
This proof of the vitally important role played by the red-blood corpuscles led, naturally, to renewed studies of these infinitesimal bodies. It was found that they may vary greatly in number at different periods in the life of the same individual, proving that they may be both developed and destroyed in the adult organism. ”

“ Thus we see a living plasma is not necessary for the blood corpuscles: they flourish in a dead one. The blood plasma is not alive.
In the days of venesection we were taught that the last act of vitality in blood when drawn from the body was its coagulation, but is this really any more a vital process than the clotting of sour milk? I think not.
In the same category with milk and blood plasma, we must place lymph, the fluids in the pleura, pericardium, peritoneum and synovial sacs, and also the cerebro-spinal fluid; none of them is alive. ”

“ The three great channels, then, by which the blood purifies itself, by which it gets rid of its waste, are the lungs, the kidneys, and the skin. Through the lungs, carbonic acid and water escape; through the kidneys, water, ammonia in the shape of urea, and various salts; through the skin, water and a few salts. As the blood passes through lung, kidney, and skin, it throws off little by little the impurities which clog it, one at one place, another at another, and returns from each purer and fresher. ”

“ Again, many instances are known in which two distant tissues communicate with one another by means of chemical messengers, bodies termed hormones (ὁρμάειν, to stir up) , which are produced by one group of cells, and sent to the other group to excite them to activity. Here, also, the path by which such messengers travel is the blood stream. A further and most important manner in which the circulating fluid is utilized in the life of an animal is seen in the way in which it is employed in protecting the body should it be invaded by micro-organisms. ”

“ The advantage gained in the vertebrate animal by retaining the blood in a closed system of tubes lies in the great diminution of resistance to the flow of blood, and the consequent great increase in rate of flow past the tissue cells. Hence any food stuffs which can travel quickly through the capillary wall to the tissue cell outside can be supplied in proportionately greater quantity within a given time, without requiring any very great increase in the concentration of that substance in the blood. ”

“ There is always an interchange between the blood within the vessels and the fluid outside of them; the passage of fluid from the vessels is facilitated by the increased pressure within them, just as pressure upon a filtering fluid increases the rapidity of filtration, and the increase of pressure within veins and capillaries impedes passage of tissue fluid into them. The fluid accumulates within the tissues leading to dropsy, or the accumulation may take place in some of the cavities of the body. The diminished flow of blood through the lungs prevents its proper oxygenation ”

“ The excretory system of kidneys and similar structures collects the ash-waste produced by the burning tissues, and discharges this from the whole mechanism, like the ash hoist of a steamship. The circulatory system, made up of smaller and larger vessels, with or without a heart, transports and propels the blood through the body, carrying the absorbed foods, the supplies of oxygen, and the waste substances of various kinds. All of these four systems are concerned with "commissary" problems, so to speak, which every individual must solve for and by itself. ”

“ But the lymph and the blood, everything considered, can hardly be looked upon as two separate and distinct liquids. Not only do they supplement each other in their work and possess striking similarities, but each is made in its movements to pass into the vessels occupied by the other, so that they are constantly mixing and mingling. For these and other reasons, they are more properly regarded as two divisions of a single liquid—one which, by adapting itself to different purposes,27 supplies all the conditions of a nutrient fluid for the cells. ”

“ Pulsation, therefore, is accomplished by a double agency: that is to say, the expansion or dilatation is accomplished by the blood, but the contraction or systole is accomplished in the egg by the membrane of the vesicle, in the fœtus after birth by the auricles and ventricles of the heart; and these alternate and mutually associated efforts once begun, the blood is impelled through the whole body, and thus the life of animals is perpetuated. ”

“ The speaker had instituted his experiments on excided but living kidneys, through which he conducted defibrinized blood of the same animals, under pressures which he was able to vary at pleasure between 80 mm. and 190 mm. Fifty experiments on dogs whose blood and kidneys were, during the experiment, kept at 40° C., yielded the result that the blood of starving animals induced no secretion of urine, which on the other hand showed itself in copious quantities where normal blood was conducted through the kidney. ”

“ The blood is a colourless fluid, containing a great number of round red blood-discs, which, from their minute size and vast numbers, seem to stain it red. They may be likened to a fleet of little boats, each capable of being laden with a freight of oxygen gas, while the stream in which they float is saturated with carbonic acid gas. ”

“ For one thing—among many—there is the matter of blood supply. Incorrect blood matching causes death in a transfusion. This is not because of the mismatch in the blood stream per se, it is because the metabolism of the entire human body is not matched to the different type of blood. ”

“ Others, considering the pain in his Kidneys during the Transfusion and the swelling of his Stomach, which was presently follow'd by Evacuations above and below, do believe, that the new Blood entring in great quantity, caused a plenitude, and a fermentation in the great Vessels, which could not but be follow'd by all those effects. To which may be added, that almost all those, into whose Veins other Liquors than blood have been injected, have found the same Accidents. ”

“ It both carries new materials to all the tissues, and removes the worn out particles of matter. This is effected by the plasma. It both conveys oxygen and removes carbonic acid. This is done through the corpuscles. Some singular experiments have {106}been tried to illustrate the life-giving power of the blood. An animal that has bled so freely as to be at the point of dying, is promptly brought back to life by an operation called transfusion, by which fresh blood from a living animal is injected into the blood-vessels of his body. ”

“ That the blood of the living has a peculiar vivifying force, in its transference from one organism to another, is one of the clearly proven re-disclosures of modern medical science; and this transference of blood has been made to advantage by way of the veins, of the stomach, of the intestines, of the tissue, and even of the lungs—through dry-spraying. ”

“ A totally different appearance, however, is produced when the disease has attacked large areas. Under these circumstances large amounts of the specific active agent reach the blood-stream by absorption and diffusion. ”

“ If the web of a frog's foot be brought in the field of a good microscope, and set against a strong light, the blood may be seen in circulation, with the most wonderful effect. Each vessel, and every globule of blood, can be seen most distinctly, and the junction of the arteries and veins can be clearly traced. The little boats of nutrition may be seen chasing each other in rapid succession, and when the animal exerts itself to escape, the flow of the blood increases ”

“ But, on rising to come ashore, the blood makes its way again through the lungs, as soon as the animal begins to respire.
As in all land animals a large portion of the mass of blood continually circulates through the lungs, which would be stopped, if the free access of air were excluded; so we find in fish a great number of blood-vessels passing through the gills, which must be perpetually wet, lest the blood should, in like manner, be checked, and consequently stagnate in its progress. ”

“ It is allowed, and has been promulgated by all authors, that the blood is one of the most active agents in the animal economy—in repairing waste, in affording peculiar fluids necessary in that economy, in supplying organs with materials for carrying on their functions, &c.; and yet all this, according to some, is accomplished by a dead animal fluid; no one can plausibly object to the laws by which the blood is governed being referred to the power of life, and to their being called Vital Principles. ”

“ Organs are first deprived of their blood, in exactly the same way as has been described on p. 164. They can then be subjected directly to hydrolysis, after the pieces of tissue have been dried, as much as possible, between filter papers. If it is desired to collect larger quantities of the same tissue, then the tissue, freed from blood, is boiled for ten minutes in water, and is subsequently preserved in sterilized water with chloroform and toluol. ”

“ Another mode of stimulating or exciting the whole system is, by putting into it a larger quantity of blood than it naturally contains. This is entirely similar to the breathing of oxygen; especially if arterial blood be used, which has already imbibed its spiritous part from the atmosphere. In the last century the transfusion of blood was proposed not only as a mode of curing diseases, but of restoring old people to youth ”

“ Numerous conduits distributed through the various limbs bring them pure blood, much like the garden water-supply, and, further, the intervals between these conduits have been wonderfully arranged by Nature from the outset so that the intervening parts should be plentifully provided for when absorbing blood, and that they should never be deluged by a quantity of superfluous fluid running in at unsuitable times. ”

“ During this embryonic life the newly-formed blood does not communicate with the vessels in the maternal system—the two circulations being juxtaposed, but independent; there is not, as the belief in the seventeenth century was, a natural transfusion of the mother's blood into that of the embryo, because the solid particles or globules of each circulate and remain in each of unequal size. The study of the blood-elements in the animal series is interesting; they are found larger in fish and reptiles than in birds and mammals, whose vital activity depends on other powers. ”

“ In microscopic experiments it is usual to see globules of blood regurgitate from the capillary vessels again and again, before they pass through them; and not only the mouths of the veins, which arise from these capillaries, are frequently seen by microscopes to regurgitate some particles of blood during the struggles of the animal; but a retrograde motion of the blood in the veins of these animals, from the very heart to the extremities of the limbs, is observable by intervals during the distresses of the dying creature. ”

“ The blood is collected in a glass or plastic graduated container and stored under refrigeration. The study of blood donors has, incidentally, given insights into the physiology of bloodletting since the volume customarily removed from a donor is about the same in volume as that taken by a bleeder (one pint or 500 cc) . [86]
The annual physical examination today includes taking a small amount of blood from the finger or a vein in the elbow. This blood is then analyzed for the presence of biochemical components of such diseases as diabetes, anemia, arteriosclerosis, etc. ”