A treatise on the motive powers which produce the circulation of the blood / By Emma Willard.

  • Willard, Emma, 1787-1870.
Date:
1846
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the motive powers which produce the circulation of the blood / By Emma Willard. Source: Wellcome Collection.

    125/200 (page 101)
    Second Part of the Tenth Objection“ The ves- sels through which the blood is impelled from the lungs, are, and must of necessity be, arterial, other- wise there would be no pulsation, for the veins never pulsate. The pulmonary arteries, therefore, are these vessels, since none other of this class reach the lungs. But how can this be, since there are valves which prevent the motion of the blood in that direc- tion, and if this were not the case, in what manner could the blood thus reaching the heart be sent to the other parts of the system? But suppose the blood to be impelled from the lungs by the pulmonary veins into the left ventricle, how then could it pass by the aorta to the other parts of the system, except by the contraction of the heart ?” Here we are in a denser fog than ever, on account of confounding pulsation with circulation. The veins, it is true, do not pulsate, but nevertheless they circulate the blood. We are told that “the vessels through which the blood must be impelled from the lungs must be arteries or there would be no pulsa- tion.” Whatthen? There may be and doubtless is, from the lungs to the heart a rapid circulation, and this is all we contend for. But the name “ pul- monary veins” is given to this part of the blood’s course, and very absurdly too, because they carry