Filaments Resting state Electrical impulse (Action Potential) reaches axon terminal.
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Transcript of Filaments Resting state Electrical impulse (Action Potential) reaches axon terminal.
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
Vesicles with acetylcholine (Ach) bind to cell membrane & releases Ach into synaptic cleft
Ach
Ach binds to receptors on motor end plate
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