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IMG - number of muscle fibers per motor unit maybe as high...

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Cassandra Pierre BIO 345 Dr.John Abdirkin Muscles and muscle tissue Contraction of a Skeleton Muscle A skeletal muscle contracts with varying force and for different periods of time in response to stimuli of varying frequencies and intensities. A contracting muscle does not always shorten and move the load. o Isotonic contraction: muscle length changes o Isometric contraction: tension builds to the muscle's peak producing capacity, but the muscle neither shortens nor lengthens. o Concentric contraction: the muscle shoftens and does work. o Eccentric contraction: the muscle contracts as it lengthens . Muscle tension: the force exerted by a contracting muscle on an object. o Load: the opposing force exerted on the muscle by the weight of the object to be moved. o Isometric: when muscle develops but the load does not move. 'l lre Motor l]nit A motor neuron and all the muscle fibers it supplies are called motor neuron. Each muscle is sc'rved by at least one motor nerve) which
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Unformatted text preview: number of muscle fibers per motor unit maybe as high as several hundred or as few as four. T'he Muscle Twitch The response of a motor unit to a single action potential of its motor neuron is called muscle twitch. A myogram is a graphic recording of contractile activity to witch a muscle is attached during the investigation of muscle contraction at a laboratory.The three distinct phase of each twitch myogram : o Latent period: first millisecond when muscle contraction stafi. . Period of contraction: when crossed bridges are active. o Period of relaxation: period of contraction followed by the period of relaxation. Muscle Metabolism The body provides the energy needed for contraction. Store ATP: As a muscle contracts, ATP provide the energy for cross bridge movement and detachment and for operation of the calcium pump. The only source of energy used directly for contractile activities....
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