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all of the same fiber type thus share properties

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Unformatted text preview: ls innervated by the same motoneuron are !!!!!!!!!!!! all of the same fiber type, thus – share properties such as contraction velocity, max. force, endurance 42 KNES 462 ©FK ‘08 KNES 462 white muscle generate higher force than red muscles The Motor Unit IV sir charles sharington--termed the motor unit MU1 wikipedia him CNS (spinal cord) MU2 43 largest motor units have largest bodies and thickets axons makes sense man KNES 462 ©FK ‘08 The Motor Unit: Types • Three types of Motor Units: – slow fatigable (Type 1, red) : slower, resistant to fatigue. Generate ~ 1-10% of force of ff. Located more deeply in the muscle, highly dependent on metabolic support. Smallest motor units consist of Type 1. – fast fatigable (Type 2, pale): fast, fatigue rapidly when stimulated repeatedly. Largest force created during twitch / tetanic contraction. Closer to the surface, dependent on glycolysis. – fast fatigue-resistant: intermediate between ff and sf. 44 KNES 462 ©FK ‘08 The Motor Unit: Force graphs white-early peak int--well it is intermediate red--- no peak 46 KNES 462 ©FK ‘08 KNES 462 The Motor Unit: Properties • Close match between neuronal and muscle fiber properties: – ff fibers innervated by larger diameter axons, – sf fibers innervated by smaller diameter axons, with low frequency firing rates. contraction speed of the...
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This document was uploaded on 03/19/2014 for the course KNES 462 at Maryland.

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