. Elements of human physiology. Physiology. THE VASCULAR MECHANISM 271 which the centres are excited to action. In fine, we must complete the reflex arc affecting the vessels by considering the afferent impulses to the vaso-motor centre. The afferent impulses to this centre may be divided into pressor and depressor ; and these names are also applied to the nerves that carry such impulses. There is in the rabbit, cat, and horse a small nerve in the neck that runs up from the heart to join the vagus or its superior laryngeal branch. If after section of both vagi (to Sup-, lar. n. J Depressor « s
. Elements of human physiology. Physiology. THE VASCULAR MECHANISM 271 which the centres are excited to action. In fine, we must complete the reflex arc affecting the vessels by considering the afferent impulses to the vaso-motor centre. The afferent impulses to this centre may be divided into pressor and depressor ; and these names are also applied to the nerves that carry such impulses. There is in the rabbit, cat, and horse a small nerve in the neck that runs up from the heart to join the vagus or its superior laryngeal branch. If after section of both vagi (to Sup-, lar. n. J Depressor « sec. Sup-, lar. ^ ---S ymp. ,-Vagus RABBIT. ---Sup-. Cerv. Gang. -Depressor Cerv. symp. n. Vago. symp. DOG Diagrams of the connections of the depressor nerve in the rabbit and dog, according to Cyon. It will be noticed that in the latter animal the depressor nerve runs in the vagus trunk for the greater part of its course. prevent reflex inhibition of the heart) this nerve be cut and its central end stimulated, while the blood-pressure is being registered by means of a mercurial manometer connected with the carotid artery, a marked fall of blood-pressure is at once observed (Fig. 151). This fall of pressure is hardly notice- able after section of the splanchnic nerves, showing that the stimulation of the depressor has affected the vaso-motor centre, inhibiting the constrictor impulses that normally pass down the splanchnic nerves. The splanchnic dilatation that is brought about by excita- tion of the depressor nerve may be demonstrated by enclosing. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Starling, Ernest Henry, 1866-1927. Chicago : W. T. Keener
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