Which of the following structures is/are necessary to initiate the muscle action potential?
Select all that apply.
A. actin
B. t-tubule
C. tropomyosin
D. motor end plate
E. muscle fiber
F. troponin
G. acetylcholine
H. calcium
I. ACh receptor-channels
J. myosin
K. ryanodine receptor
L. Ca2+-ATPase
M. motor neuron
