First principles of medicine / By Archibald Billing.

  • Archibald Billing
Date:
1831
Catalogue details

Licence: Public Domain Mark

Credit: First principles of medicine / By Archibald Billing. Source: Wellcome Collection.

    18/142 (page 10)
    heart causes an unequal stream; it must be remembered that in the tube, unwounded, that force would have been expended in stretching the artery, whereas the artery when wounded, ceases to be other than as a sim- ple tube, the elasticity not being called into operation, on account of the escape of the blood from the wound. The most simple mechanical illustration perhaps, 1s the double bellows of a smith’s forge, which keeps up a constant current of air; though the handle works with intermissions, so that the blast into the fire would be in puffs, if it were not for the weight of the upper half of the bellows, which keeps forcing out the air ina con- tinued current, whilst the hand is drawing back to make another impulse. It has been supposed that the circular fibres of the ARTERIES were muscular, and that they contracted and relaxed at each pulse, and that the throb felt, was caused by a dilatation of the artery; those fibres are NOT MUSCULAR, but more approaching to a ligamen- tous tissue, firm and, though elastic, not yielding to the force of the heart, but on the contrary, preserving the CALIBRE of the artery UNIFORM, as may be seen by laying bare an artery in a living animal, or when the artery is laid bare in an operation; it 1s LONGITUDI- NALLY that the arteries are STRETCHED at each injec- tion from the heart, by which their capacity is increased, the consequence of which, from their being bound down in various places, is, that there is a SERPENTINE motion in the artery where it is at all loose. The fibres of the middle coat of the artery being arranged circularly, allow of the separation laterally, and thus accommodate themselves to the elongation, of