Absorption (biology)

“ On the contrary, it is made up of living protoplasmic cells; absorption is not a physical, but a physiological, process, in which the living epithelium cells stand as guardians of the portals, ready to challenge and, if need be, modify the rate of passage. Osmosis and diffusion undoubtedly play some part in absorption, but they alone are not sufficient to account for what actually takes place in the absorption of digestion products, and other substances from the living intestine. ”

“ The Decomposition of any remaining Portion, and the adoption of measures best calculated to obviate its absorption. Where the substance is in a solid form, and acts by absorption, we should be very cautious how we favour its solution; while, if it exists in a liquid state, our object must be to render its active portion insoluble; this problem involves a series of questions which are wholly chemical. In order to prevent, or retard, the absorption of the active matter, we must, to a great degree, depend upon the agency of vital adjuvants ”

“ We cannot deny that in the natural state the sensibility of the absorbents has a particular type, to which certain substances are alone accommodated, and which alone on this account can be absorbed. The exercise of the organic sensibility then always pre-exists in absorption, as it does in secretion, nutrition, &c. Thus in the physical phenomena, the exercise of gravity always precedes the fall of heavy bodies. ”

“ Time would fail me to discuss the many other phenomena of the living body which have been found on investigation to be non-vital. Digestion, which Prout said it was impossible to believe was chemical, is now known to take place as well without the body as within it, and to result from non-vital ferments. Absorption is osmotic, and its selective power resides in the structure of the membrane and the diffusibility of the solution. Respiration is a purely chemical function. ”

“ Effusions of water into large cavities, as into that of the abdomen or thorax, or into the ventricules of the brain or pericardium, are more difficult to be reabsorbed, than the effusion of fluids into the cellular membrane; because one part of this extensive sponge-like system of cells, which connects all the solid parts of the body, may have its power of absorption impaired, at the same time that some other part of it may still retain that power, or perhaps possess it in an increased degree ”

“ Thus closely do the absorptions in the two cases run together—thus emphatically do the molecules assert their individuality. As long as their number is unaltered, their action on radiant heat is unchanged. Passing from the lime light to the incandescent spiral, the absorptions of the smaller equivalent quantities, in the two tubes, were 23.5 and 23.4 per cent.; while the absorptions of the larger equivalent quantities were 32.1 and 32.6 per cent., respectively. This constancy of absorption, when the density of a gas or vapor is varied, I have called "the conservation of molecular action." ”

“ The evidence for the non-absorption of oxygen lies chiefly in the fact that plants obtain, in the form of water and carbonic acid, a larger quantity of that element than they require, and in place of absorbing, are constantly exhaling it. ”

“ There appears, from the presence of nitrogen in equal quantity in both kinds of blood, to be an absorption and evolution of that gas, simply from physical laws, and independent of any application of it to the nutrition of the animal ”

“ An increased absorption is produced by an increased susceptibility of the ‘absorbent orifices.’ And thus, in this view, each organic power may be contemplated either as sensibility or as contractility, and may be supposed to be rendered more intense by magnifying either of these its aspects; although, in fact, neither can be conceived to be increased without an exactly commensurate increase of the other. ”

“ Aggregation is excited by almost all the stimulants which induce movement; such as the glands being touched two or three times, the pressure of minute inorganic particles, the absorption of various fluids, even long immersion in distilled water, exosmose, and heat. Of the many stimulants tried, carbonate of ammonia is the most energetic and acts the quickest: a dose of 1/134400 of a grain (.00048 mg.) given to a single gland suffices to cause in one hour well-marked aggregation in the upper cells of the tentacle. ”

“ The negative general proposition, that animal substances do not absorb these salts, contributes to the explanation by accounting for the absence of a counteracting cause, namely, absorption by the stomach, which in the case of other substances possessed of the requisite chemical properties, interferes to prevent them from reaching the substances which they are destined to dissolve. ”

“ But where the bulk is considerable, or where the activity is such as to involve much waste and repair, or where both these characteristics exist, there is a necessity for a system of blood-vessels. It is not enough that there be adequately extensive surfaces for absorption and aeration; for in the absence of any means of conveyance, the absorbed elements can be of little or no use to the organism at large. ”

“ The movement of each sort of material is independent, and a substance will continue to enter until it becomes equally distributed. If it is being used or stored, it may be absorbed in large amounts. Similarly water moves from the places where there are fewest particles of all the dissolved substances, i.e., where there is most water, toward the places where there is relatively less water. As water is constantly evaporating from land plants large quantities of water must be absorbed to balance this loss. The absorption of all substances is subject to regulation by the living protoplasm. ”

“ In vertebrate animals this is done by the lymphatics and lacteals, in plants chiefly by the roots. See Absorbents.
In physics, absorption of colour is the phenomenon observed when certain colours are retained or prevented from passing through transparent bodies; thus pieces of coloured glass are almost opaque to some parts of the spectrum, while allowing other colours to pass through freely. In chemistry absorption is the taking up of a gas by a liquid, or by a porous solid. ”

“ From the fact in physics that liquids rise in capillary tubes, the inference has been drawn that absorption [165] in living vessels also takes place from capillary attraction. But in the animal body the application of the principle is undoubtedly modified by the properties peculiar to organization, and one of the most remarkable proofs of this is the circumstance of the absorbent vessels in different situations having to some extent a specific adaptation to the qualities of the substances upon which they are severally destined to act. ”

“ When on the contrary some branches of the absorbent systems have their motions inverted in consequence of the previous exhaustion of their sensorial power by any violent stimulus, other branches of it have their absorbent power greatly increased. Hence continued vomiting, or violent cathartics, produce great absorption from the cellular membrane in cases of dropsy; and the fluids thus absorbed are poured into the stomach and intestines by the inverted motions of the lacteals and lymphatics. ”

“ The changes of the gases in the blood, together with the processes which take place in the intestines or in the liver, and which have so often been made the subject of the most thorough investigations, would be beyond the reach of our methods and we could only determine that these organisms have the power to convert comparatively large quantities of albumen into carbonic acid, water, and urea, with the absorption of oxygen—in short, the process would be similar to that of yeast fermentation. ”

“ But in addition to fluid, the tissue spaces may at times be found to contain solid matter in the form of particles, which may represent the debris of destroyed cells, or which are, as is quite commonly the case, micro-organisms. Apparently such material cannot be removed from a tissue by absorption into the blood stream—indeed in the case of living organisms such an absorption would in many instances rapidly prove fatal, and special provision is made to prevent such an accident. ”

“ Where the material is too large to be taken up by an individual cell, the dissolution is brought about by the cells surrounding the material, to which they closely apply themselves, and by the secreting of the ferment, a gradual process of erosion is brought about with ultimate absorption. ”

“ May not the oxygen be restored back again by evolution from those bodies which have absorbed it, upon their decomposition? Thus there would be a successive absorption and evolution as the process of nature went on; which would tend to keep up an equal distribution of oxygen. ”

“ We frequently observe an unusual quantity of mucus or other fluids in some diseases, although the action of the glands, by which those fluids are separated from the blood, is not unusually increased; but when the power of absorption alone is diminished. ”

“ They may be distinguished from those fluids, which are the consequence of deficient absorption, by their not possessing the saline acrimony, which those fluids possess; which inflames the skin or other membranes on which they fall ”

“ It is of course to be understood that diffusion experiments made with dead parchment membranes cannot necessarily be expected to throw much light upon the rate of absorption of these bodies through the living membranes of the stomach and intestine, where, as Waymouth Reid143 has well said, we have to deal with an absorptive force dependent, no doubt, upon protoplasmic activity, and comparable, in part at least, to the excretive force of a gland-cell. ”

“ A particularly fine basis for experiments seems to be supplied by thromboses, which one might be able to attack effectively by means of properly directed ferments, and so bring about their absorption. ”

“ Absorption is the vital function by which nutritive materials are selected and imbibed for the sustenance of the body. Absorption, like all other functional processes, employs agents to effect its purposes, and the villi of the small intestine, with their numberless projecting organs, are specially employed to imbibe fluid substances ”

“ The molecular changes caused by absorption of nutritive matter from organic substance in contact, or from adjacent organic substance, initiate96 motions which are indefinite where the organization is low, and which become more definite with the advance of organization. At the outset, while the undifferentiated protoplasm is everywhere absorbent and everywhere contractile, the changes of form initiated by the physical stimulation of adjacent nutritive matter are vague, and ineffectually adapted to utilization of it ”

“ The method consists in comparing the intensity after transmission through a layer of known thickness of the absorbent with the intensity of light from the same source which has not passed through the medium, k being thus obtained for various thicknesses and found to be constant. In the case of solutions, if the absorption of the solvent is negligible, the effect of increasing the concentration of the absorbing solute is the same as that of increasing the thickness in the same ratio. ”

“ The cold dampness of the hands of some people is caused by the deficient absorption of perspirable matter; the clammy or viscid feel of it is owing to the mucous part being left upon the skin. The coldness is produced both by the decreased action of the absorbent system, and by the evaporation of a greater quantity of the perspirable matter into the air, which ought to have been absorbed. ”

“ To the questions,—What are the forces by which absorption, secretion, and the vital motions, of fluids are produced?—no satisfactory answer has been returned. Yet still some steps have been made, which it may be instructive to point out.
12. In Absorption it would appear that a part of the agency is inorganic; for not only dead membranes, but inorganic substances, absorb fluids, and even absorb them with elective forces, according to the ingredients, of the fluid. A force which is of this kind, and which has been termed Endosmose, has been found to produce very curious effects. ”

“ This is to compress the bowels and increase their absorption, and it thus removes one principal cause of corpulency, which is the looseness of the skin. Secondly, he should omit one entire meal, as supper; by this long abstinence from food the absorbent system will act on the mucus and fat with greater energy. Thirdly, he should drink as little as he can with ease to his sensations; since, if the absorbents of the stomach and bowels supply the blood with much, or perhaps too much, aqueous fluid, the absorbents of the cellular membrane will act with less energy. ”

“ All soluble mineral substances—acids, alkalies, salts, and soluble compounds of the earths and metals—are absorbed in the stomach and intestines. The conditions and the process of absorption have been already stated. When solid they are first dissolved, when in a dense solution diluted down by the gastric fluid before they are absorbed. Thin watery liquids are quickly taken up. Motion on one side, and pressure on the other, hasten the process. I am not inclined to make any exception to this rule. This leads me to make some remarks on the Endosmotic theory of the action of saline purgatives. ”

“ The more the process of absorption is studied, however, the more clearly do we see its dependence upon the functional power of the living epithelial cells, a fact which plainly emphasizes the physiological nature of the process. ”