Term
| Action Potential is initiated and propagates to motor neuron axon terminals. |
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Definition
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Term
| Ca2+ enters axon terminals through voltage-gated Ca2+ channels |
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Definition
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Term
| Ca2+ entry trigger release of ACh from axon terminals |
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Definition
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Term
| ACh diffuses from axon terminals to motor end plate in muscle fiber |
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Definition
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Term
| ACh binds to nicotinic receptors on motor end plate, increasing their permeability to Na and K |
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Definition
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Term
| More Na moves into the fiber at the motor end plate than K moves out, depolarizing the membrane and producing the end-plate potential (EPP) |
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Definition
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Term
| Local currents depolarize the adjacent muscle cell plasma membrane to its threshold potential, generating an action potential that propagates over the muscle fiber surface and into the fiber along the T-tubules. |
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Definition
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Term
| Action potential n T-Tubules induces DHP receptors to pull open ryanodine receptor channels, allowing release of Ca2+ from lateral sacs of the SR. |
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Definition
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Term
| Ca2+ binds to troponin on the thin filaments, causing tropomyosin to move away from its blocking position, thereby uncovering cross-bridge bind sites on actin |
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Definition
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Term
| Energized mason cross-bridges on the thick filament bind to actin |
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Definition
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Term
| Cross-bridge binding triggers release of ATP hydrolysis products from myosin, producing an angular movement of each cross-bridge |
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Definition
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Term
| ATP binds to myosin, breaking linkage between actin and myosin thereby allowing cross-bridges to dissociate from actin |
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Definition
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Term
| ATP bound to myosin is spit, energizing the myosin cross-bridge |
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Definition
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Term
| Cross-bridges repeat, producing movement (sliding) of thin filaments past thick filaments. Cycles of cross-bridge movement continue as long as Ca2+ remains bound to troponin |
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Definition
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Term
| Cytosolic Ca2+ concentration decreases as Ca2+-ATPase actively transports Ca2+ into the SR. |
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Definition
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Term
| Removal of Ca2+ from troponin restores blocking action of tropomyosin, the cross-bridge cycle ceases, and the muscle relaxes. |
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Definition
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