A text-book of pathology : for practitioners and students / by Joseph McFarland.

Date:
1904
Catalogue details

Licence: In copyright

Credit: A text-book of pathology : for practitioners and students / by Joseph McFarland. Source: Wellcome Collection.

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

    105/844 (page 105)
    from changes in the blood, changes in the vessel, or changes in the rate of circulation. 1. Changes in the Blood.—(a) The accidental or experimental introduc- tion of certain chemical and physical substances into the blood, by injuring the corpuscles and so liberating the fibrin ferments, may occasion thrombosis. Among the substances capable of doing this are alcohol, ether and chloro- form, thymus extract, and heterogeneous blood serums. (/>) The occasional accidental entrance of pus, cancer cells, etc., may bring about thrombosis. (1c) The metabolic product of certain micro-organisms seem to be power- ful fibrin ferments; among these may be mentioned especially those of pneumonia and diphtheria. Cd) Extensive burns, possibly by the loss of fluid from the blood, are oc- casionally followed by thrombosis. 2. Changes in the Vessels.—Diseases leading to thickening, and roughen- ing of the intima with deposition of calcareous salts are particularly to be mentioned, and of these arteriosclerosis is the most important. Endocarditis with calcification produces coagulation of the blood less often than might be imagined. In aneurysms the irregular and uneven vessel walls almost inva- riably predispose to thrombosis. Inflammatory changes in or near the vessel walls, with resulting changes in the intima, are not infrequently followed by thrombosis. Ligation of the vessels, which causes laceration of the delicate internal coat, is constantly followed by thrombosis. The presence of one thrombus in a vessel always tends to the formation of others, extending higher and involving new portions of the vessel. Thus, using a rather common exam- ple, if a thrombus form in a small branch of the internal iliac vein, it may gradually extend to the internal iliac vein and project into it. A new throm- bus may be then formed within the larger vein, extending to the junction with the external iliac vein, which in its turn may become blocked, and a con- tinued growth of the thrombus, extending along these vessels, may continue down the leg, producing the not uncommon disease known as phlegmasia alba do lens or “ milk leg.” 3- Changes in the Speed of the Circulation.—These are rather fruitful souices of thrombosis. The thrombi found post mortem within the heart and great \ essels are probably formed during the death agony or just after death. As the blood current slows the white corpuscles show a disposi- tion to adhere to the walls of the vessels. Blood plaques are deposited upon them so soon as the leukocytes cease to move, and the resulting mass, which appears hyaline from degeneration of the plaques, extends into the umen of the vessel. Fibrin is almost immediately deposited upon this, cor- puscles become entangled in it, and soon a more or less solid mass or throm- usis formed. The thrombus maybe yellowish, grayish, or red according to the number of red corpuscles it contains. When the current is slowed t e nutrition of the part supplied by the vessels is altered and the chemistry o the blood becomes changed, this variation from the normal itself tending toward thrombosis. Structure and Variety of Thrombi.—Thrombi are usually composed ° superimposed layers of fibrin, entangling a variable number of red and w ite corpuscles. I hey are commonly distinctly laminated or stratified upon naked-eye examination, the lamina sometimes varying considerably in color and thickness. The longer the thrombus remains within the body the firmer and dryer it becomes and the more closely it adheres to the vessel walls. he coagula formed in the heart and great vessels after death are dark-red masses of soft, jelly-like consistence, not adherent, and aptly described as