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23 Cards in this Set
- Front
- Back
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motor unit
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motor neuron + muscle fiber it innervates
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to increase tension/force
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recruit motor units or increase frequency
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slow motor units
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myosin with long cycle time, recruited 1st, lots of mt
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fast motor units
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myosin with rapid cycling rates, higher power, type IIa (sustained power), and IIb (fast, glycolytic)
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steps in transmission at NMJ
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Ach synthesis + storage, AP opens Ca ch, Ca influx, vesicles fuse, Ach release, binds to nicotinic receptor
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choline acetyltransferase
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converts acetyl CoA and choline to Ach
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acetylcholinesterase
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converts Ach to acetate and choline
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curare
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blocks nicotinic receptor
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clostridium botulinum
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prevents Ach release |
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neostigmine
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AchE inhibitor
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Downer cows
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hypocalcemia, decreases Ach release at NMJ
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excitation-contraction coupling
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depolarization of motor end-plate coupled to muscle contraction (DHP and RyR)
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sliding filament theory
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H zone and I band shorten, A band does not change
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length-tension relationship
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stretched/shortened muscle has less force
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load-velocity relationship
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max load with zero velocity and reverse
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isometric contraction
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plank, no length change
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isotonic contraction
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pushup, length change, generates movement
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types of isotonic contraction
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concentric (shortens), eccentric (lengthens)
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muscle twitch phases
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latent, contraction, relaxation
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treppe
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stimulation with complete relaxation between
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wave summation
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stimuli without complete relaxation between
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incomplete tetanus
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individual twitches distinguishable
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complete tetanus
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high frequency APs, no relaxation phase
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