Lectures on some of the applications of chemistry and mechanics to pathology and therapeutics / by H. Bence Jones.

  • Jones, Bence, 1814-1873.
Date:
1867
Catalogue details

Licence: Public Domain Mark

Credit: Lectures on some of the applications of chemistry and mechanics to pathology and therapeutics / by H. Bence Jones. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    ieffect. The mode of action of mechanical remedies is at pre- sent much more comprehensible than that of chemical remedies. Motion increases chemical action, and rest checks it. When the blood is carried through a muscle at rest the quantity of oxygen remaining in the blood is nearly 1^ per cent., but if the muscle is in motion then the quantity of oxygen is reduced to I^^q per cent. In other words, when motion takes place there is much more chemical action than when the muscle is at rest. Motion in two ways increases chemical action—1st, directly by conversion of force, and, 2nd, indirectly by bringing the molecules more closely into contact, so that the latent energy can be changed into active force. This is chiefly effected by the circulation bringing fresh and larger amounts of oxygen in contact with the hydrogen and carbon, phosphorus and sulphur of the textures. Kest lessens the supply of oxygen, lessens the pressure in the capillaries; lessens the mixture and contact of molecules in the textures, and thus diminishes chemical action. Heat and cold act both chemically and mechanically in promoting or checking chemical action. Heat acts directly by conversion of force; it also probably acts by dilating the small arteries and veins, and thus permitting freer circulation, and the consequent increased chemical action. Cold acts directly by stopping chemical action, and indirectly by constricting the small arteries and veins, and thus hindering the circulation and preventing the contact of the oxygen with the combustible and nutritive substances. Food acts both chemically and mechanically,—chemically, 1st, by furnishing latent force, and, 2nd, material for the formation of the organs by which that force is made active. It acts mechanically by the solid parts increasing chemical action in the stomach, and by the fluid parts adding to the mass of liquid in the blood and by the dissolved solids that pass into the blood, adding to its specific gravity, and thus altering the osmotic actions throughout the system. Eood may be divided into water, salts, carbonaceous and nitrogenous matters. The water and salts do not take a