Muscle Physio

Muscle Physiology

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Gavin Page: Muscle Physiology

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Functional Units • Motor Unit: One motor neuron and all of the muscle fibers it supplies – Large Motor Unit: One motor unit branches to many fibers • For coarse, broad movements

– Small Motor Unit: One motor unit branches to few fibers • For precise movements

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Electrical Response • Myogram: measures muscle response to nervous stimulation (electrical activity within muscle fibers).

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Muscle Response • Twitch: The response of muscle to a single, brief threshold stimulus – 3 Phases • Latent: From point of stimulus to beginning of contraction (when tension begins to increase) • Contraction: When muscle begins to shorten until the point of greatest

tension

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• Relaxation: Muscle tension decreases and muscle returns to resting

Gavin Page: Muscle Physiology

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Graded Responses

• • • •

->variations in degree of muscle contraction ->required for proper control of skeletal movement Change the frequency of the stimulus Change the strength of the stimulus

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Responses • Wave Summation: – Unchanging stimuli applied in rapid succession – Muscle unable to relax – Tension generated is summed together

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Responses • Tetany: – Summations increase tension to maximum – Produces one long, sustained contraction

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Responses • Recruitment: – Increased voltage to muscle fibers – Recruits additional muscle fibers – More fibers contracting yields more tension

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Responses • Homeostatic Conditions: – ATP, Ca++, temperature, oxygen – Treppe: muscle warm up • Stair case effect

– Fatigue: decreased ability to contract • Caused by: – ATP Deficit

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Muscle Tone • Constant state of slight tension • Maintains body posture, balance • Initiated by spinal reflexes respond to proprioiceptors • Maintains readiness to contract

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Got Notes? • http://www.rit.edu/~gsp8334

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Gavin Page: Muscle Physiology

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