Complete multiple choice below:
1) During skeletal muscle excitation, the initial depolarization derives from_____.
a) Neuromodulators binding to and opening voltage-gated Na+ channels.
b) Acetylcholine binding to and closing ligand-gated K+ channels.
c) Opening of mechanically-gated Na+ channels.
d) Acetylcholine binding to and opening non-specific ligand-gated channels.
e) None of the above

2) In whole skeletal muscles, such as the biceps, increased force of contraction is normally produced by
a) recruitment of motor units
b) temporal summation
c) Operating at optimal muscle length
d) A and B are correct
e) A, B, and C are correct

3) In skeletal muscle fibers the normal process of excitation - contraction coupling depends on
a) spread of a muscle action potential across the sarcolemma and through the transverse tubules (T) of the myofiber
b) release of Ca++ from the Sarcoplasmic Reticulum (SR)
c) binding of Ca++ by troponin
d) A and C
e) All are correct