The series of membranous channels that surround each myofibril is the
A) sarcoplasmic reticulum.
B) sarcoplasm.
C) sarcomere.
D) sarcolemma.
E) endomysium.
Question 2
At rest, active sites on the actin are blocked by
A) myosin molecules.
B) troponin molecules.
C) tropomyosin molecules.
D) calcium ions.
E) ATP molecules.