The essentials of healthA text-book of anatomy, physiology, hygiene, alcohol, and narcotics . a collection of nerve cells that the ganglia have consid-erable size. The sympatheticsystem consists of two rows ofthese ganglia, one row on eitherside of the spinal column. Itconsist also of nerves which pro-ceed from the ganglia to theorgans in the thoracic, the ab-dominal, and the pelvic sympathetic nerves do notgo to the skin, neither are theyconnected with the specialsenses, nor are they under thecontrol of the will. This systempresides over the involuntaryprocesses of the body ; as
The essentials of healthA text-book of anatomy, physiology, hygiene, alcohol, and narcotics . a collection of nerve cells that the ganglia have consid-erable size. The sympatheticsystem consists of two rows ofthese ganglia, one row on eitherside of the spinal column. Itconsist also of nerves which pro-ceed from the ganglia to theorgans in the thoracic, the ab-dominal, and the pelvic sympathetic nerves do notgo to the skin, neither are theyconnected with the specialsenses, nor are they under thecontrol of the will. This systempresides over the involuntaryprocesses of the body ; as thecirculation, the digestion, therespiration, the absorption, thenutrition, and the involuntarymuscles. It also controls thesecretions of glands, and hasmuch to do with the amount ofblood distributed to the variousorgans and tissues. The ganglia are connectedwith each other by small nervefibers, while other minute fibersconnect the ganglia with thecerebro-spinal system. Thus one organ is made to actin u sympathy with another, so that if one part suffersin anv way another suffers with Fig. 89. Diagram of thecerebro-spinal system : c, cer-ebrum ; cl, cerebellum ; s,spinal column ; N, nerves forthe upper and lower limbs ;n, nerves going to the mus-cles and the skin. THE NERVOUS SYSTEM. 255 Nerve Tissue. There are two kinds of nerve tissue;one is composed of nerve fibers, and the other of nervecells. The presence of numbers of the nerve cells givesa gray color to the tissue, while the nerve fibers appearwhite. Hence an accumulation of nerve cells is calledthe gray substance, and a collection of nerve fibers iscalled the white substance. The nerve cells representthe centers of activity from which the orders are nerve fibers are simply the conductors, conveyingthe messages from place to place. The gray substancetherefore, represents the seat, or origin, of the mysteri-ous forces of the nervous system; while the whitesubstance represents only so many fibers for the tr
Size: 1894px × 1319px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectphysiology, bookyear1
