File:A healthy body. A textbook on anatomy, physiology, hygiene, alcohol, and narcotics. For use in intermediate grades in public and private schools (1889) (14762950142).jpg

Identifier: healthybodytextb00stow (find matches)
Title: A healthy body. A textbook on anatomy, physiology, hygiene, alcohol, and narcotics. For use in intermediate grades in public and private schools
Year: 1889 (1880s)
Authors: Stowell, Charles H(enry) 1850- (from old catalog)
Subjects: Human physiology
Publisher: Chicago, J.C. Buckbee and company
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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Fig. 61. A diagram illustrating the origin of the spinal nerves from the spinalcord ; (3) is a spinal nerve; (1) and (2) are the roots, which originate fromthe gray matter of the cord ; G, a collection of nerve-cells: (1) the motoryroot, (2) the sensory root. be quickly drawn away from the threatened injury, andyet the mind will know nothing of it. Fig. 62 illustrates
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Fig. 62. A diagram illustrating reflex action: s, the skin; M, a muscle. THE NERVOUS SYSTEM. 169 how the impression goes from the skin of the foot to thespinal cord, and then down to the muscles. The spinal cord is one great reflex centre. Impres-sions are carried to it by the sensory nerves, and,withont going to the brain, they are at once sent outto some muscle through the motorynerves. Even the will is not strongenough to control all the reflex acts,for if we inhale pepper, we either coughor sneeze, and cannot prevent it. It ispurely a reflex act. We may determine ^H not to sneeze, but it is of no use. M The Nerve-Current. The peculiar powercarried by the nerves is called the nerve-current, or nerve-force. It travels alongthe nerves at the rate of over one hun-dred feet a second. We do not knowwhat this nerve-force is, although wecan interfere with its action. We maybe seated in a cramped position, so thatsome nerve is pressed; the nerve-current is disturbed,and when we try to move

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