Contraction of Skeletal Muscle Sliding filament theory of contraction (Excitation-Contraction Coupling)
Functional Anatomy of Skeletal Muscle
Arrival of nerve impulse (action potential) Influx of Ca 2+ into the pre-synaptic membrane Attraction of synaptic vesicles Fusion of vesicular & pre-synaptic membranes Release of neurotransmitter (Ach) into the synaptic cleft Binding of Ach with its nicotinic receptor on post-synaptic membrane Influx of Na 1+ into the post-synaptic membraneFiring of action potential on post-synaptic membrane (sarcolemma)
Propagation of action potential along sarcolemma and deep via T-tubules Release of Ca 2+ from sarcoplasmic reticulum to be near the myofilaments
What happens at the sarcomere level?
full full contraction Sarcomere shortens toward
full full contraction Sarcomere shortens toward
full full contraction Sarcomere shortens toward
full full contraction Sarcomere shortens toward
Cleavage of ATP into ADP and P i Ca 2+ binds troponin C
Detachment of P i Actin-myosin cross-bridge
Tilting of myosin heads and sliding of actin along myosin
Relaxation Arrival of new ATP
The cycle is repeated
Detachment of P i
Sliding Sliding
Relaxation
The cycle is repeated
Until full Until full contraction The cycle is repeated
Until full Until full contraction The cycle is repeated
Until full Until full contraction The cycle is repeated
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