Capillary action

“ We find, however, upon the 205capillaries evidence of the same kind of fine nucleated fibrils, which we find to be present in the fine nerve twigs, as far as we can follow them in their course towards their final distribution. To explain the action of nerves on the process of secretion we would have to assume either that the nerves accompanying the capillaries also influence the gland cells, or that the glands are stimulated to activity by some changes in the condition of the capillary wall furnishing a greater amount of oxygen and nutritive fluids. ”

“ In the limbs of paralytic patients, in animals in whom the nerves are cut in order to render a part insensible, does not the capillary circulation continue as usual, when the nervous action has ceased there? ”

“ Capillaries have one wall, which is the continuation of the inner wall of the artery, thus making the capillary so thin that fluid finds its way easily through it into the surrounding tissues.
Some parts of the body are more vascular than others and some tissues of the body, such as the cornea of the eye, the epidermis, cartilage, the substance of the brain, etc., are entirely destitute of capillaries. ”

“ From all that I have said, it is evident that in the organs whose capillary system contains in part blood, and in part different fluids, the proportion of the first to the others is infinitely variable; that a thousand causes in a state of health, as in that of disease, by bringing to the organ more or less blood, can fill more or less its capillary system. ”

“ All over the body there are, though you can not see them, networks of capillaries. All the arteries end in capillaries, and in them begin all veins. Supposing a little blood-corpuscle be squeezed in the narrow pathway of a capillary in the muscle of the arm. ”

“ The capillaries are spread so thickly that there are not many places in the body where living cells are more than a very small fraction of an inch from one of them. The cells do not, however, lie right against the capillaries, but are separated from them by tiny spaces filled with tissue fluid. In order for material to get from the blood to any living cell, then, it must pass through the wall of the capillary into the fluid which fills the tissue space and from that in turn to the cell itself. ”

“ OF THE GENERAL CAPILLARY SYSTEM.
This system exists in all the organs; all are in fact composed of an infinity of capillaries, which cross, unite, separate and unite again, by communicating in a thousand ways with each other. The vessels of any considerable size, those among the arteries, in which the blood circulates by the influence of the heart, and those among the veins, which correspond to the first, have really no connexion with the structure of the organs; they wind along their interstices; and are lodged in the cellular texture that separates their lobes ”

“ At the beginning the bone cells are lying near one of the tiny blood vessels known as capillaries, which are the exchange stations for material between blood and the stationary part of the body fluid. Thus these cells are favorably located for obtaining materials from which bone can be constructed. As they proceed with the formation of bone they always leave tiny passages open between themselves and the blood capillary. ”

“ Such a system of structures would, of course, be almost impossible to demonstrate with any degree of certainty. I have not, of course, sufficient reason to deny such an arrangement, and would not consider it improbable if we had not, in the capillaries of the frog’s muscle (and other structures) evidence 202certainly not in favor of such an assumption. The fine nerve fibrils supplying the capillaries are richly supplied with nuclei, although the cells which build up the walls of the capillary are by far more insignificant elements than the secreting cells of the gland. ”

“ The diseases of their capillary system are no doubt different from those of animals in their progress and their nature; but they exhibit always the same general character, because they are derived from the same properties, organic sensibility and insensible contractility. ”

“ These are the communications of the capillary system that explain how the skin becomes livid on the place on which a dead body has for a long time lain, as on the back, for example; how by turning a dead body, so that the head may hang down, it becomes full of fluid; how, on the contrary, by placing upright the body of one dead from apoplexy, asphyxia, &c. the capillary system of the face is freed in a great measure from the blood it contained ”

“ The capillary vessels were not known in Harvey's time: the capillamenta of Cæsalpinus were not the 10 capillaries, but the νευ̂ρα (Greek: neura) of Aristotle. It was believed that the blood, between the smallest arteries and the smallest veins, made its way through "blind porosities" in the tissues, as water percolates through earth or through a sponge. The first account of the capillaries is in two letters (De Pulmonibus, 1661) from Malpighi, professor of medicine at Bologna, to Borelli, professor of mathematics at Pisa. ”

“ Though the setae are often extremely elongate—sometimes several times the length of the body—they are nearly always slender, and there is no reason to suppose that a perfect, or air-tight, tube is formed; hence it is probable that capillary attraction is really the chief agent in the ingestion of the fluid. ”

“ In the body the blood within the capillary is a stream of raw material about to be made muscle, or bone, or brain, and of stuff which, having been muscle, or bone, or brain, is no longer of any use, and is on its way to be cast out. The actual making of muscle, or of bone, or of brain, is carried on, and the work of each is done, outside the blood, in the little plots of tissue into which no red corpuscle comes. ”

“ That property of liquids known as capillary attraction has been frequently called to the aid of perpetual-motion seekers, and the fact that although water will, in capillary tubes and sponges, rise several inches above the general level, it will not overflow, has been a startling surprise to the would-be inventors. ”

“ Hence why the two circulations can be separate; why more than half of the organized beings have only the capillary. This is the most important, since it immediately pours out the materials of nutrition, of exhalations, of absorption: thus it exists in all organized beings. We cannot conceive of any one without it, because we cannot conceive of any one that is not continually composed and decomposed by nutrition.
From what we have thus far said, it is evident, that the blood after it has arrived in the capillary system, is moved there only by the tonic influence of the solids ”

“ The blood charged with different natural or morbific substances is a stimulant more or less capable of putting in play the motion of the heart. 3d. The general capillary system, according as it receives a greater or less quantity of blood, or refuses admission to that which the arteries send there, &c. produces necessarily numerous varieties in the pulse. There are but few causes relative to the arteries themselves. ”

“ Here we see fine fibrils, provided with nuclei, exceeding the fibres two to four times in thickness, entwining the capillary, thus coming in contact with each of the cells composing the capillary wall. In the (submaxillary) gland there are similar structures to be influenced; at least in the capillary as well as in the gland, we have cells lying side by side to be influenced by nerves—hence we might expect similar structures.
Although the books in general have very little to say about the nerve supply of the capillaries, yet it is a fact, and can well be demonstrated, e. ”

“ In like manner, whenever we move any muscle, some of its particles decay and pass away. It is in the capillaries, which are all over the body, that this change takes place. The blood-vessels that convey the pure blood from the heart, divide into myriads of little branches that terminate in capillary vessels like those lining the air-cells of the lungs. The blood meanders through these minute capillaries, depositing the oxygen taken from the lungs and the food of the stomach, and receiving in return the decayed matter, which is chiefly carbonic acid. ”

“ The capillaries or bloodvessels are finer than hairs, and they are so interlaced and interwoven with nerves that it is impossible to put down the point of the finest needle without wounding several of those minute organs. ”

“ So much is certain, that in that region, where arteries and veins are not to be seen, there are also no separate nerve twigs, and that here the union or coalescence of nerve and tissue which the nerves are to influence must have taken place. If one considers the fine meshes of the capillary network enveloping the ducts, and keeps in mind the abundance of nuclei belonging to the capillary, the membrana propria and the duct cells proper, he can imagine how difficult it must be to follow the course of the nerves through and among all these structures. ”

“ These coverings, or membranes, as they are called, in turn, derive their materials for growth and function from the minute capillary blood-vessels which, in almost infinite number, supply them, while all portions of brain tissue are together dependent upon the regularity of the heart’s supply of blood to [Pg 163] enable them to discharge their functions in a normal manner. ”

“ As the blood goes the round of the circulation, the nutrient capillary vessels select and secrete those parts which are similar to the nature of the structure, and the other portions pass on; so that every tissue imbibes and converts to its own use the very principles which it requires for its growth ”

“ Rheumatism. Gout. Leprosy. II. 1. The most minute membranes are unorganized. 2. Larger membranes are composed of the ducts of the capillaries, and the mouths of the absorbents. 3. Mucilaginous fluid is secreted on their surfaces. III. Three kinds of rheumatism. I. 1. The capillary-vessels are like all the other glands except the absorbent system, inasmuch as they receive blood from the arteries, separate a fluid from it, and return the remainder by the veins. ”

“ Bearing in mind, that these cover-slips are not cut out from a flat piece but from the surface of a sphere, it is evident that only with glasses thus prepared, can it be expected that a capillary space should be formed between two of them, in which the blood spreads easily. For with the smallest unevenness or brittleness of the glass it is an impossibility for the one to fit every bend of the other. ”

“ In the very minute terminations of the capillary arteries in those structures, where the molecular change of the body goes on, the current of the blood is very slow, to enable the warmth and sustenance 56 of the body to be kept up by the chemical actions of destruction and reproduction of tissue. ”

“ The cutaneous capillaries, especially those of the face, are more mobile, that is, more easily excited into increased action, or more easily become torpid, from less variation of sensorial power, than any other parts of the system, which is owing to their being perpetually subject to the vicissitudes of heat and cold, and of extension and corrugation. ”

“ While the membrana propria of the ducts can be separated 199rather easily from the inclosed cells, it is different from the surrounding network of capillaries. It seems impossible to remove the capillaries from the duct-walls; while, in the gland-structure proper, among the alveoli, the separation of the capillary from an alveolus, can with little difficulty often be accomplished, so that a piece of capillary can be examined without any other structures lying above or beneath it. ”

“ To prove to us that when we start from a false principle, the whole chain of consequences drawn from it is false, though these consequences may be rigorously deduced from each other. In fact, most philosophers have considered the skin as a kind of fountain with numerous capillary tubes, always throwing out in the same time the same quantity of fluids, and being able consequently to be subjected, like inert capillaries which pour out fluids, to proportions and calculations of quantity. ”

“ The smallest fibres become rigid; the minute capillary vessels corrugate, admit no fluids to pass through them, and at length change into fibres; the larger blood-vessels grow hard and narrow; in short, all the outlets of the body become contracted, and in a manner close: whence the dry, shrivelled, and inflexible state of old age. ”

“ No sooner is the sucker firmly fixed to the skin, than the mouth becomes slightly everted, and the edges of the saws are thus made to press upon the tense skin, a sawing movement being at the same time given to each, whereby it is made gradually to pierce the surface, and cut its way to the capillary blood-vessels beneath. ”

“ When the hand is cold the arterioles are so constricted that blood only passes through the wider and more direct capillaries. As the skin becomes warm it flushes, the arterioles dilating and all the capillary networks becoming filled with blood. Muscular movements express the blood out of the capillaries, as may be seen by the blanching of the skin which occurs on clenching the hand. ”

“ With the most complete reduction effected by the highest operation of light, its substratum or under-layer becomes black. The mucus passes over into reduced carbon. Beneath the vitreous epidermis there is thus a metallic pigmentary membrane.
Hairs.
2276. Capillary vessels, which simply convey mucus, but are elongated singly above and from out the cutis, are Hairs. The idea of the hair is a capillary vessel, the contents of which are no longer blood, but reduced mucus. It is an indifferent capillary vessel. The hair is hollow and contains an oil, which determines the colour. ”