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 contains axons of hundreds of motor neurons. The
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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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This note was uploaded on 12/19/2011 for the course PHYS 345 taught by Professor Dr.abdirkin during the Spring '11 term at St. Thomas FL.

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

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