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.

    17/142 (page 9)
    posed and is carried off by absorbents ; as to the chan- nel in the growth of an exostosis, or in the natural srowth of the bones of an infant’s head, it is merely the deposit of bony matter by the side of those vessels which previously existed. Arteries are endowed with a power of contracting on their contents so as to continue full, even when a considerable quantity of blood has been lost either by hemorrhage or artificial means; this contraction then is the action of arteries, and is distinct from, and op- posed to, the contraction and action of the heart. This point it is necessary to understand clearly, in speaking of the phcenomena of disease The HEART contracts by muscular action and relaxes ALTERNATELY, the ARTERIES keep up a CONSTANT contractile pressure on their contents, not an alternate contraction and relaxation, but a continued contractile effort which is overcome by the action of the heart, when there is much blood sent into them they are dis- tended, and if there be little blood sent into them, as after hzemorrage, their tendency to contract causes them to close, so as to keep always full, and to pre- serve a constant stream of the blood even during the temporary relaxation of the heart; and the ARTERIES YIELDING and adapting themselves to the pressure of the heart and RECONTR ACTING on their contents, whilst the heart is relaxed and filling, is the cause of the EQUABILITY of the STREAM in the VEINS, nay, the stream even in the arteries is much less in jets than is supposed by those who judge from the mode of its flowing from a wounded artery; for though, when there is a free escape from the wound, the impulse of the B