Volume 1

A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling.

Landois, L. (Leonard), 1837-1902. Lehrbuch der Physiologie des Menschen. English

Date:: 1891

Credit: A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling. Source: Wellcome Collection.

41/602 page 1

$Physiology of the Blood. ♦ f [The blood is aptly described by Claude Bernard as an internal medium which 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 up some of these new substances, and receives in exchange certain waste products which have to be got rid of. Its composition is thus highly complex. Besides carrying the new nutrient fluids to the tissues, it is also the great oxygen-carrier, as Avell as the mediimi by which some of the waste products, e.g., CO^, urea, are removed from the tissues, and brought to the organs, e.g., the lungs, kidneys, skin, which eliminate them from the body. It is at once a great pabulum-supplying medium and a channel for getting rid of useless materials. As the composition of the organs through which the blood flows varies, it is 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 Avhich characterise blood as a ivhole.'] 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 dicliroic—i.e., by reflected light it appears 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 with a pattern on it, and pouring it off 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 matter is suspended in the form of fine particles—the blood-corpuscles. Hence, it is possible to separate the colouring-matter from the fluid part of the blood by filtration. This is accomplished by mixing the blood with fluids which render the blood- corpuscles sticky or rough. If mammalian blood be treated with one-seventh of its volume of solution of sodic sulphate, or if frog's blood be mixed with a 2 per cent, solution of sugar {Joh. Müller) and filtered, the shrivelled corpuscles, now robbed of part of their Avater, remain upon the filter. (2) Reaction.—The reaction is alkaline, owing to the presence of disodic phosphate, E'a2lIP04, 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, perhaps, the coloured corpuscles take part, owing to the decomposition of their colouring matter. A high$