A manual of physiology : including physiological anatomy for the use of the medical student / by William B. Carpenter.

  • William Benjamin Carpenter
Date:
1846
Catalogue details

Licence: Public Domain Mark

Credit: A manual of physiology : including physiological anatomy for the use of the medical student / by William B. Carpenter. 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.

    376/610 (page 352)
    VENOUS CONGESTION.—INFLUENCE OF GRAVITY. ticed in almost every case of long-standing dyspnoea ; especially when this is accompanied (as it usually is) by hypertrophy and dilatation of the right ventricle of the heart. 609. The Venous circulation is much more liable than the Arterial to be influenced by the force of Gravity; and this influence is particu- larly noticeable, when the tonicity of the vessels is deficient. The following experiments performed bv Dr. Williams, to elucidate the infl uencc of deficient firmness in the walls of the vessels, and of ravi- tation, over the movement of fluids through tubes, throw great light on the causes of Venous Congestion. A tube with two equal arms hav- ing been fitted to a syringe, a brass tube two feet long, having several right angles in its course, was adapted to one of them, whilst to the other was tied a portion of a rabbit's intestine four feet long, and of calibre double that of the brass tube, this being arranged in curves and coils, but without angles and crossings. When the two ends were raised to the same height, the small metal tube discharged from two to five times the quantity of water discharged in a given time by the larger but membranous tube ; the difference being greatest, when the strokes of the piston were most forcible and sudden, by which the intestine was much dilated at its syringe end, but conveyed very little more water. 'When the discharging ends were raised a few inches higher, the difference increased considerably, the amount of fluid discharged by the gut being much diminished ; and when the ends were raised to the height of eight or ton inches, the gut ceased to discharge, each stroke only moving the column of water in it, and this subsiding again, without rising high enough to overflow. When the force of the stroke was increased, the part of the intestine nearest the syringe burst. 610. From these experiments it is easy to understand, how any deficiency of tone in the Venous system will tend to prevent the ascent of the blood from the depending parts of the body, and will conse- quently occasion an increased pressure on the walls of the vessels, and an augmentation in the quantity of blood they contain. All these conditions are peculiarly favourable to the escape of the watery part of the blood from the small vessels; and this may either infiltrate into the areolar tissue, or it may be poured into some neighbouring serous cavity, producing dropsy. Thus it happens, that such effusions may often be traced to that state of deficient vigour of the system, which peculi- arly manifests itself in want of tone of the blood-vessels ; and that it is relieved by remedies which tend to restore this. In many young females of leuco-phlegmatic temperament, for example, there is a tendency to swelling of the feet, by edematous effusion into the areolar tissue, in consequence of the depending position of the limbs ; the cedema disap- pears during the night, but returns during the day, and is at its maxi- mum in the evening. And the congestion which frequently manifests itself in the posterior parts of the body, towards the close of exhaust- ing diseases, in which the patient has lain much upon his back, is