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Filaments. Resting state. Electrical impulse (Action Potential) reaches axon terminal. Impulse opens Calcium Channels, rapid influx of Calcium into terminal. Vesicles with acetylcholine (Ach) bind to cell membrane & releases Ach into synaptic cleft.
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Impulse opens Calcium Channels, rapid influx of Calcium into terminal
Vesicles with acetylcholine (Ach)bind to cell membrane & releases Ach into synaptic cleft
Vesicles with acetylcholine (Ach) bind to cell membrane & releases Ach into synaptic cleft Ach
Ach receptors opens Na+ channels, causes an influx of sodium into muscle
Sodium influx triggers a muscle impulse (electrical signal) in all directions of muscle fiber.
Electrical impulse travels across Sarcolemma, down t-tubules, and across cisternae Sarcolemma
Electrical impulse travels across Sarcolemma, down t-tubules, and across cisternae
Sarcoplasmic Reticulum releases Calcium into Sarcoplasm Sarcoplasmic Reticulum
Ca2+ (Calcium) Triggers muscle contraction by binding to troponin
Tropomyosin moves and exposes actin filaments to cross bridges
Cross bridges bind to actin & pulls actin forward (ADP is released from cross bridge)
Cross bridges bind to actin & pulls actin forward (ADP is released from cross bridge)
Videos • Breakdown of ATP • Synapse Transmission • Action Potential Across Sarcolemma • Shortening Sarcomere
Relaxation • Calcium pumps return Calcium to Sarcoplasmic reticulum • Acetylcholinesterase clears ACh from synaptic cleft • ATP binds to cross bridge & myosin is released from actin * • ATPase converts ATP to ADP using energy to cock cross bridge* • Tropomyosin cover actin filaments • * Note: ATP is required for both muscle contraction & relaxation
Myofibrils • Actin Filaments “thin” • Anchored to z-lines (filament proteins) • I bands (light color) = actin + z-lines • Myosin Filaments “thick” • A-band (dark color) = Myosin filaments + overlapping Actin filaments • H-zone (slightly lighter) = Myosin filaments between overlapping actin • Sarcomere • Area between 2 z-lines • Functional unit of skeletal muscle • During contraction adjacent z-lines approach each other