File:Carpenter's principles of human physiology (1881) (14594786218).jpg

Identifier: carpentersprinci00carp (find matches)
Title: Carpenter's principles of human physiology
Year: 1881 (1880s)
Authors: Carpenter, William Benjamin, 1813-1885 Meneses, Henry Power
Subjects: Human physiology Physiology
Publisher: London : J. & A. Churchill
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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he Heart. The Kight half represents the course of the inhi-bitory, and the Lett the course of the accelerating nerves of theHeart; the arrows showing the direction in which impressionsare conveyed. The ellipse at the upper extremity of the Vaguslooking like the section of the nerve is intended to represent theVagal nucleus or centre. In this diagram the nerves are incor-rectly made to cross, instead of passing behind, the aorta. * Journ. of Anat. and Physiol., vol. iii. 1869, p. 410.t Rutherford, On the Influence of the Vasrus on the Vascular System, Trans. Roy. Soc.of Edinb., vol. xxvi. 1870. +Lu(lwigs Arbeiten, 1867, p. 128. U 2 292 OF THE CIRCULATION OF THE BLOOD. arresting, or inhibitory power over the Cardiac movements as the Vagus itself.In man this nerve is represented by the superior Cardiac branch of the Vagus.If this nerve be divided on both sides and the upper cut surface of the nerveon either side be irritated no effects are produced, but if the lower cut surface Fig. 129.
Text Appearing After Image:
After. During. Before. Tracing showing effect of stimulation of Vagus. The tracing must be readfrom right to left. The rise and fall of the tracing as a whole constitutethe respiratory curves. be irritated, the heart stops in diastole. Slowing of the Cardiac beats occursif only one Vagus be divided. The fibres of the nerve therefore appear toconduct impulses downwards (as indicated by the arrow in Fig. 128.). Itmight be supposed that these fibres pass to the Cardio-motor centre, and exerta direct inhibitory influence upon it, but several circumstances render itprobable that an intermediate apparatus, or inhibitory mechanism which wemay term an inhibitory centre, exists in the heart between the vagal branchesrunning to the heart and the ultimate fibres of these branches. For, in thefirst place, when the Cardio-inhibitory nerves are stimulated a very appreciableinterval elapses before the inhibitory action is manifested. Thus Pfliigerfound that even when the stimulus applied was strong

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