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Weight and Work Skeletal Muscle. Definitions. Motor Unit : a motor neuron and all muscle fibers it innervates. Twitch : single contraction in response to a single stimulus/AP. Isotonic : muscular contraction where constant tension continues while the length of the muscle changes. Concentric
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Definitions • Motor Unit: a motor neuron and all muscle fibers it innervates. • Twitch: single contraction in response to a single stimulus/AP. • Isotonic: muscular contraction where constant tension continues while the length of the muscle changes. • Concentric • Eccentric • Isometric: muscular contraction against resistance in which the length of the muscle remains the same.
Work • Work is accomplished only when an object is moved. • Work = Force X Distance • Force = muscle tension required to overcome the load (weight of the object). • In an isometric contraction where no object is moved (muscles do not change length) the work done = zero.
Load/Velocity relationship • Load is an important determinant of shortening velocity. Load = velocity
3 Muscle Fiber Types Slow Oxidative Fast Oxidative Fast Glycolytic Postural muscles Bird flight muscles Mammal breast muscles
Lithobatespipiens • Referred to as Ranapipiensalso. • Opportunistic feeders • Occurs through much of US and Canada (cosmopolitan) • Status is controversial: widespread, but most populations throughout range are decreasing rapidly. • Commonly used in research.
HOMEWORK!!!! • Write an entire lab report, again. • Include answers to ALL labscribe questions WITHIN the body of the paper. • Follow my formatting instructions!!!!!! • Due on November 28/29.
Next Week… • Have a GREAT Thanksgiving!!!