BIO210Chpt9notesopen

Acetic acid choline prevents muscle fiber contraction

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acetic acid & choline prevents ____________________ muscle fiber contraction w/o ____________________ To contract, an ____________________ must be generated in ____________________ : ______________________________ : AP propagated along sarcolemma, [Ca 2+ ] intracellular ____________________ Muscle & Muscle Tissue –Contraction Stimulus Skeletal muscles are stimulated by somatic motor neurons motor neuron axons CNS via nerves to skeletal muscle, each axon forms several branches as it enters muscle, ea. __________ _______________junction w/ ______________________________ NMJ is usu. __________ on length of muscle fiber NMJ = axon terminals , ____________________ , sarcolemma ____________________ axon terminal & muscle fiber separated by ____________________ = synaptic cleft
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terminal ____________________ contain __________ ; junctional folds have ____________________ Muscle & Muscle Tissue – Muscle Action Potential Generation of a muscle action potential to start - resting sarcolemma polarized – ____________________ across PM Action potential caused by ___________ in electrical ___________ occurs in 3 steps: ______________________ , ______________________ , ______________________ Generation of an AP across the sarcolemma begins w/ end plate potential end plate potential (local _________________ ) ACh binding opens ___________ ion channels, simultaneous diffusion of ___________/___________ >Na + diffuses in, [Na + ] inside sarcolemma less – local depolarization = EPP Muscle & Muscle Tissue – Muscle Action Potential Figure 9.8 Muscle & Muscle Tissue – Muscle Action Potential Following depolarization, the EPP ___________ to ___________ PM areas voltage-gated Na + channels open; Na + influx, ___________ critical voltage level = threshold; when threshold reached, AP initiated muscle fiber contraction AP spreads across __________ voltage-gated Na + channels open in ___________ depolarization to threshold The membrane must __________ to __________ – ____________________ fiber cannot be stimulated - until ____________________ - restore __________ ____________________ close , ____________________ channels open; K + efflux restores RMP ionic conditions of resting state restored by ____________________ Muscle & Muscle Tissue – Muscle Action Potential Figure 9.11 Muscle & Muscle Tissue – Muscle Action Potential
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AP reaches ___________ voltage-gated Ca 2+ channels open ___________released to synaptic cleft ACh binds to receptors on sarcolemma opens ligand-gated Na + & K + channels ___________________ opens voltage-gated Na + channels AP propagation T tubules, voltage-sensitive proteins shape SR releases Ca 2+ cytosol Muscle & Muscle Tissue –Role of Calcium Summary Ca 2+ has an important role in contraction of skeletal muscle low [Ca 2+ ] intracellular : _ ____________, active sites on actin; myosin heads cannot attach to actin, muscle fiber _________ high [Ca 2+ ] intracellular : Ca 2+ _______________ , troponin ________ & tropomyosin __________ myosin- binding sites myosin heads bind to actin, sarcomeres shorten & muscle __________ nervous stimulation ceases, _ ____________ _ ____________ SR & _ ____________ _ ______ Cross bridge cycle continues as long as _ ____________ ’d & sufficient _ ____________ present cross bridge formation- high E _________head attaches to _________ power stroke - myosin head ___________ thin filament toward M line cross bridge detachment - ___________ to myosin head, __________ myosin head “ charging " - __________________ “charges” myosin head Muscle & Muscle Tissue – The Motor Unit The __________________ is the nerve-muscle __________________ motor unit = __________________ & (4- ~00’s) __________________ innervated motor nerve - axons of __________________; ea. muscle innervated by __________________ axons _________ terminals, each _________ w/ a single __________________ Motor unit muscle fibers __________________throughout muscle _________ so 1 motor unit fibers activation _________________ of _________ muscle contract ________________, helps prevent fatigue larger # = _________control smaller # = _______control
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Muscle & Muscle Tissue – Muscle Twitch A muscle _________ is a motor unit _________ to a _________of its motor neuron simplest __________________ – w/ myogram
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  • Spring '16
  • muscle tension

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