Contraction of Skeletal Muscle Sliding filament theory of contraction (Excitation-Contraction...

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Contraction of Skeletal Muscle Sliding filament theory of contraction ( Excitation-Contraction Coupling )

Transcript of Contraction of Skeletal Muscle Sliding filament theory of contraction (Excitation-Contraction...

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Contraction of Skeletal Muscle

Sliding filament theory of contraction

(Excitation-Contraction Coupling)

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Functional Anatomy of

Skeletal Muscle

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Arrival of nerve impulse (action potential)

Influx of Ca2+ into the pre-synaptic membraneAttraction of synaptic vesiclesFusion of vesicular & pre-synaptic membranesRelease of neurotransmitter (Ach) into the synaptic cleftBinding of Ach with its nicotinic receptor on post-synaptic membraneInflux of Na1+ into the post-synaptic membraneFiring of action potential on post-synaptic membrane (sarcolemma)

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Propagation of action potential along Propagation of action potential along sarcolemma and deep via T-tubulessarcolemma and deep via T-tubules

Release of Ca2+ from sarcoplasmic reticulum to be near the myofilaments

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What happens at the sarcomere level?

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full full contractionSarcomere shortens towardSarcomere shortens toward

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full full contractionSarcomere shortens towardSarcomere shortens toward

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full full contractionSarcomere shortens towardSarcomere shortens toward

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full full contractionSarcomere shortens towardSarcomere shortens toward

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Cleavage of ATP into ADP and PCleavage of ATP into ADP and P ii

CaCa2+ 2+ binds troponin Cbinds troponin C

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DetachmentDetachment of Pof Pii

Actin-myosin cross-bridgeActin-myosin cross-bridge

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Tilting Tilting of myosin heads and of myosin heads and slidingsliding of actin along of actin along myosinmyosin

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RelaxationRelaxation

Arrival of new Arrival of new ATPATP

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The cycle is repeatedThe cycle is repeated

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DetachmentDetachment of Pof Pii

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SlidingSliding

SlidingSliding

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RelaxationRelaxation

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The cycle is repeatedThe cycle is repeated

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Until full Until full contraction

The cycle is repeatedThe cycle is repeated

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Until full Until full contraction

The cycle is repeatedThe cycle is repeated

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Until full Until full contraction

The cycle is repeatedThe cycle is repeated

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