A manual of the practice of medicine / by George Hilaro Barlow.
- George Hilaro Barlow
- Date:
- 1861
Licence: Public Domain Mark
Credit: A manual of the practice of medicine / by George Hilaro Barlow. Source: Wellcome Collection.
Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.
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![the right imderstaucling of those important atfections, iuflamma- tion, ]ia3morrhage, and dropsy. Congestion or hyperemia may arise, 1, from the increase of the flow of blood to the part; 2, from an increase of the capacity of the part for blood ; and, 3, from a diminished flow of blood from the part. (1.) The first of these constitutes the active congestion of most authors, and the active or sthenic hyper£emia of Andral, sometimes called also engorgement. It is not inflammation, neither does it necessarily lead to it, though it bears a most important relation to that complex process, since when the latter does occur, active or sthenic hypersemia is the fii'st step towards it. In order to the right understanding of the nature of con- gestion, and also of the right application of the means for its removal, it is necessary to bear in mind, that, an increase in the quantity of blood sent to a part, is not necessarily the result upon an increased quantity in the system at large, or even of an increase of the injecting force of the heart. To explain this we may recur to some physiological con- siderations respecting the moving powers of the circulation. The first propellrag power of either circulation is the systole of the ventricle by which the artery is filled and its elasticity overcome. As soon, however, as the systole is completed, the sigmoid valves being closed, the pressure which the large arteries exert upon the blood by their contractility can act only in propelling it in a continuous current, so that we may regard the large arteries and sigmoid valves as an appa- ratus for converting an intermitting motion into a continuous one; such as is the fly-wheel of a steam-engine ; or, to use the more appropriate comparison of Sir Charles Bell, the elasti- city of the artery acts, like the compressed air in a fire- engine, to produce a continuous current from a force acting at intei-vals. It has been shown that, in addition to its yellow elastic tissue, the middle fibrous coat of the arteries contains non- striated muscular fibre, giving to it a degree of real muscular contractility in addition to the mere physical property of elasticity; yet there is no reason for concluding that these fibres produce any peristaltic movement which would exert a propelling force upon the contents of the vessels, though they probably have the power of regulating the calibre of the artery, for purposes to be hereafter explained. The movement of the blood in the capillaries, however, appears to be greatly assisted by a different power, viz., an attractive force arising from, tlie mutual aflinity of' the blood in the capillaries, and the tissues surrounding those vessels.](https://iiif.wellcomecollection.org/image/b21509104_0043.jp2/full/800%2C/0/default.jpg)
