An introduction to pathology and morbid anatomy / by T. Henry Green.

  • Green, T. Henry (Thomas Henry), 1841-1923.
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to pathology and morbid anatomy / by T. Henry Green. Source: Wellcome Collection.

    34/628 (page 6)
    and blood-vessels from the intestines; the various excretory oi'gans give off urea and, in small quantity, other nitrogenous bodies, carbonic acid, and water. Supposing the body to be in nutritive equilibrium—neither gaining nor losing weight— the amounts excreted will account for the nitrogen, carbon, and hydrogen taken in as food. Putting aside water, certain salines, and oxygen, which are essential to* life, the food-stuffs are albumen, carbohydrates, and fats—the materials of which the body consists. It is evident that a large amount of heat must be set free in the breaking-down of these bodies to the excreta above-mentioned, and this is the source of the force by which every act is performed. The blood carries the prepared food-stuffs to the capillaries, where they pass out with the lymph to come into actual contact with the cells—some in solu- tion, others only in suspension. Certain, or all, of these bodies are now taken up (apparently actively, for albumen will not diffuse from a watery fluid), and become of the substance of a cell, replacing some older material which has been broken down to supply force for assimilation and all other actions of the cell. Tliis breaking-down of cell-substance consists in the union of it wiih oxygen obtained from the blood, and stored by the tissues in some unknown way. All such oxidation processes are believed to take place in the cells, not in the blood ; and this almost necessitates that all food shall become part of a cell before it is oxidised; it is not oxidised directly. Although the tissues of the body and the food-stuffs have almost the same chemical composition, waste tissue is not repaired by a process of simple replacement from the food, if we except fat: when a fat of the same composition as human fat is contained in the food, it may be stored in the cells without undergoing previous change, but usually some slight addition or subtraction of hydrogen is necessary. It is probable that many changes, both analytical and synthetical, occur in the arrangement of the elements of food-stuffs before they form protoplasm, the real living tissue, and force is thus alternately liberated and rendered potential; ])ut this does not affect the main fact that the body ultimately obtains the force equivalent to the difference in heat-value between the ingesta and excreta.