Human physiology / by John Thornton.

  • Thornton, John
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Human physiology / by John Thornton. Source: Wellcome Collection.

    56/476 page 44
    from some part of the preceding one and raise the lever to a greater height. When the shocks increase more rapidly still, the individual shocks, visible at first, fuse together into one continuous curve, the lever having attained a maximum height, where it remains until the muscle is exhausted if the shocks continue. A muscle in a state of continuous contraction is said to be in a condition of spasm or tetanus. Tetanus may occur as the result of disease (lockjaw) or be produced by poisons such as strychnine. A fatigued and exhausted muscle cannot act owing to the accumulated products of action, and if left to Fig. 38.—Composition of Tetanus. Stimuli caused by a spring interrupting primary circuit by vibrating in and out of a mercury cup ; the vibration frequency is increased by shortening the spring. rest, may recover by the circulating blood bringing fresh nourish- ment and carrying off the accumulated waste products. Every contraction of a voluntary muscle in the living body is con- sidered to be tetanic in character, a sudden jerk being in reality a tetanic contraction of short duration. A good example of a clear case of tetanus is seen when a person takes hold of the handles of a strong galvanic battery in action. Cramp or tetanus is produced in the muscles of his fingers by the rapidly repeated contractions in the muscles bending his fingers, and he cannot let go. Besides doing mechanical work during contraction, the muscle produces heat and undergoes an electrical change. In
    digitised image 1
    digitised image 2
    digitised image 3