The laws and mechanics of circulation, with the principle involved in animal movement . bring it in correspondence with the functions in the lungs anddigestive processes, for producing force in the organism andmaintaining a balance. The expeditious manner in which theblood is shifted from part to part commensurate with the physi-ological requirements in the organs and organism, has its ex-planation in the high pressure in the arterial system and thepower of expanding the local vessels, the blood in consequencerushing into them instantaneously to equalize pressure. Thenecessity for a vaso-motor
The laws and mechanics of circulation, with the principle involved in animal movement . bring it in correspondence with the functions in the lungs anddigestive processes, for producing force in the organism andmaintaining a balance. The expeditious manner in which theblood is shifted from part to part commensurate with the physi-ological requirements in the organs and organism, has its ex-planation in the high pressure in the arterial system and thepower of expanding the local vessels, the blood in consequencerushing into them instantaneously to equalize pressure. Thenecessity for a vaso-motor centre to effect expansion and con-traction in the vascular system for coordinating it with the SPINAL NERVES AND DORSAL GANGLIA. 281 functions in the lungs, and for maintaining a balance in circu-lation, is, therefore, sufficiently obvious ; while to expand andcontract the lumen inheres in the vessels themselves, the nerv-ous apparatus serving to energize the actions and coordinatethem in the functions ; otherwise, it were utterly impossible tocarry on the functions in the Fig. 114.—Transverse Section of Spinal Cord and the Ganglionic Chain of SympatheticNerves, showing mode of connection between them. A, four upper intercostalnerves ; 1, ganglion on posterior root; S, nerves connecting the ganglia of the sym-pathetic with the two roots of the spinal nerves ; P P, posterior pulmonic plexus ;5, inferior cervical ganglion ; C P, branches to the cardiac plexus. In fine, this law of pressure and the power of producingrapid rhythmical expansions and contractions in the vesselsfor changing pressure inheres in the vessels themselves to theminutest capillaries, and by means of which circulation is madeto respond to the physiological requirements in the organs andorganism, otherwise impossible; while for producing equilib- 282 YASO-DILATOR AND CONTRACTOR NERVES. rium it requires the correlation of the two nervous forceswhich these opposite actions represent in the medulla o
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Keywords: ., bookcentury1800, bookde, booksubjectblood, booksubjectrespiration
