A textbook of human physiology / translated from [the] 6th German edition by W. Stirling.

  • Landois, Leonard
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: A textbook of human physiology / translated from [the] 6th German edition by W. Stirling. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    53/980
    Physiology of the Blood. [The blood i.s aptly described by Claude lleniard as an internal medium wliich acts as a go-between or medium of exchange for the outer world and the tissues. Into it are poured those substances which have been subjected to the action of the digestive fluids, and in the lungs or other respiratory organs it receives oxygen. It thus contains new substances, but in its passage through the tissues it gives U]) •some of these new substances, and receives in exchange certain waste products which have to be got rid of. Its coini)osition is thus highly complex. Besides ♦•arrying the new nutrient fluids to the tissues, it is also the great oxygen-carrier, as well as the medium by which some of the waste products, e.g., CO.,, urea, are removed/Vowi the tissues, and brought to the organs, cjj., the lungs, kidneys, skin, which eliminate them from tlie body. It is at once a great pabulum-supplying medmm and a channel for getting lid of useless materials. As the composition of the organs through which the blood flows varies, it i.s evident that its composition must vary in different parts of the circulatory system ; and it also varies in the .same individual under different conditions. Still, with slight variations, there are certain general physical, histological, and chemical properties which characterise blood as a whole.] 1. PHYSICAL PROPERTIES.—(1) Colour.—The colour of blood varies from a bright scarlet-red in the arteries to a deep, dark, bluish-red in the veins. Oxygen (and, therefore, the air) makes the blood bright red ; want of oxygen makes it dark. Blood free from oxygen (and also venous blood) is dichroic—I.e., by reflected light it ai)pears dark red, while by transmitted light it is green. [Arterial blood is monochroic] In thin layers blood is opaque, as is easily shown by shaking blood so as to form bubbles, or by allowing blood to fall upon a plate Avith a pattern on it, and i)Ouring it oft' again. [Printed matter cannot be read through a thin layer of blood spread on a glass slide.] Blood behaves, therefore, like an opaque colour, as its colouring- n\atter is suspended in the form of fine particles—the blood-cor[)Uscle.s. ileiice, it is possible to separate the colouring-matter from tlie Hiiid part of the blond hy nitration. This is accomplished by mixing the blood with fiuids wliii-h render the blood- corpuscles sticky or rough. If mammalian l)lood l)c treated with one-seventh of its volume ol solution of sodic sulphate, or if frog's blood be mixed with a 2 per cent, solution of s\igar {Joh. Miillcr) and filtered, the shrivelled corpuscles, now robbed of part of their water, remain u]iou the filter. (2) Reaction.—The reaction is alkaline, owing to the presence of disodic phosphate, NaoHPO^, and bicarbonate of soda. After blood is shed, its alkalinity rapidly diminishes, and this occurs more rapidly the greater the alkalinity of the blood. This is due to the formation of an acid, in which, iierhaps, the coloured corpuscles take part, owing to the decomposition of their colouring-matter. A high A