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.

    21/142 (page 13)
    respiration, for the glottis is sufficient to admit a free _ current of air; it is only in croup or laboured respi- ration of any kind that there can be any effect of atmos- pheric pressure. A reference to the hydrostatic principle of fluid in bent tubes finding its level will be sufficient to account for the capability of the heart, with little effort, to send the blood all over the frame, and for the re-filling of the heart after each contraction; the heart sends the blood against the force of gravitation through but a small portion of the frame, for in all the natural positions upright, or horizontal, by far the greatest portion of it is below the level of the heart ; now the blood being confined in the arterial and venous tubes will of course (on hydrostatic principles) return to the same level from which it flows; and, as to the capability of the muscular power of the heart to inject the parts that are above its level, when any person compares the force necessary to be used in doing so, with the force which an equal quantity of muscle in the arm is capable of exerting, it appears trifling, besides whoever applies the hand to an aneurismal tumour may feel the force of the heart. The blood then returning from the parts above the level of the heart, tends to refill it by gravitation, (even if not aided by the contractile pressure of the arteries) ; the blood below the level of the heart, or rather arch of the aorta, returns by the tendency to find its own level, so that the BLOoD is PRESSED into the RIGHT AURICLE by the weight of the returning blood from all the parts above the level of the heart added to the pressure caused by the difference of the height of the arch of the aorta above the right auricle of the heart and in addition by whatever remains of the contractile