Setting the stage
The events at the neuromuscular junction
(NMJ) set the stage for E-C coupling by
providing excitation. Released acetylcholine
binds to receptor proteins on the sarcolemma
and triggers an action potential in a muscle
fiber.
Axon terminal of
motor neuron at NMJ
Muscle fiber
Triad
One sarcomere
One myofibril
Synaptic
cleft
Sarcolemma
Action potential
is generated
Terminal
cistern
of SR
ACh
Ca
2+
T tubule
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Figure 9.11
Excitation-contraction (E-C) coupling is the sequence of events
by which transmission of an action potential along the sarcolemma leads to
the sliding of myofilaments.
FOCUS
Excitation-Contraction Coupling
 
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