Physiological therapeutics : a new theory / by Thomas W. Poole.

  • Poole, Thomas W.
Date:
1879
Catalogue details

Licence: Public Domain Mark

Credit: Physiological therapeutics : a new theory / by Thomas W. Poole. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

    135/250 (page 129)
    calculated to raise it in our esteem ; and considering the manner in which it is said to be beset on all sides, it deserves our warmest sympathy. 242. We have stated above the most recent theory as to the ner- vous mechanism of the heart. On such a subject we do not presume to have any opinion of our own to offer. But we are about to quote the facts and observations of physiologists themselves, with a view of ascertaining if the assumption of a much simpler mechanism would not equally account for the maintenance of the heart's action, and equally serve to explain the effects of drugs on that organ. 243. The pulsations of the heart begin, in early foetal life, before there is any vestige of a nervous system ;* and they continue, in frogs, for hours and even days, under favorable circumstances, after the heart is removed from the body, and all its nervous connections are completely severed.-|- It is evident, then, that the heart contains within itself the springs of its own action, J and that when properly nourished and its cavities supplied with blood, it is capable of fulfilling its proper functions without extraneous aid from the general nervous system. || 244. The heart is composed of striated muscular fibres, having, like other similar structures, an inherent power of contractility. Dr. Carpenter suggests that the heart's fibres may possibly have an active force of elongation, as well as an active force of contraction.§ Rhythmical movements of contraction and extension take place in the intestinal villi, during absorption.lF Alternate contractions and dilations occur in the vessels of the absorbent system also.** Dr. Wharton Jones has observed a regular rhythmical movement in the veins of the bat's wing, obviously depending on their inhe= rent contractility ; and a like movement is seen in the blood vessels of such of the lower invertebrata as have no heart.-f^f* Are not the rhythmical contractions and relaxations of the heart of a character similar to those just noted, except that they are more important to the organism, are more elaborate in themselves, and are carried o n upon a larger scale .-* And yet there is no pre- tence that these require for their continuance an elaborate and complex system of nerve-forces, such as has been inferred to exist in the case of the heart. 245. But while there are numerous facts which establish that the heart can continue its action, without extraneous aid from the ner- vous system, observations are not wanting to show that the heart's action is much modified by external nervous agency. Thus, section of the vagi causes it to pulsate faster. Faradization, which we claim to be equivalent to paralysis, of the vagi slows the heart, and *Dr. Carpenter's Human Physiol., p. 324, &^c. tDr. Burdon-Sanderson, Hand- book, <2r^c.,p. 274. J Ibid. IIDr. Carpenter's Human Physiol., pp. 324, 470. § Human Physiology, p. 473, note. Hlbid, p. 440. **Ibid, p. 455, ft Ibid, p. 455, note.