. Elements of human physiology. Physiology. THE CONTEACTILE TISSUES 117 and with the same stimuhis both work and heat production are raised by increasing the load. In fact the maximum amount of heat is produced when the muscle is made to contract against a strong spring, so that it cannot shorten at all (isometric contraction). In view of the comparison of the muscle to a heat engine, it becomes interesting to inquire into its efficiency, the I'lG. 4' Diagram of Fick's ' Arbeitsanimler' or muscle crank, a 6 is a counterbalanced lever, attached to the muscle M at m. When the muscle cont
. Elements of human physiology. Physiology. THE CONTEACTILE TISSUES 117 and with the same stimuhis both work and heat production are raised by increasing the load. In fact the maximum amount of heat is produced when the muscle is made to contract against a strong spring, so that it cannot shorten at all (isometric contraction). In view of the comparison of the muscle to a heat engine, it becomes interesting to inquire into its efficiency, the I'lG. 4' Diagram of Fick's ' Arbeitsanimler' or muscle crank, a 6 is a counterbalanced lever, attached to the muscle M at m. When the muscle contracts, the catch c carries round the circumference of the wheel D and so coils up the weight W round the axle of the wheel. When the muscle relaxes, if , is in the situation of the dotted line, the weight pulls the wheel and lever back to its original position. If, however, c, be applied to D, the backward movement of the wheel is prevented, and the nmscle is extended simply by the weight of the lever a b. Thus at each contraction the weight is drawn a httle higher, and external work is per- formed by the muscle. relation of the work to the total energy expended. This amount is found to vary within very wide limits. In a fresh muscle the heat energy may be twenty-five times as great as the work energy, but the heat evolved with each contraction diminishes with fatigue more rapidly than the work done, so that the proportion may fall to as low as three to one. In. 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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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiology, bookyear1
