Nervous stimulation of skeletal muscle results in a wave of depolarization along the plasma membrane. This electrical signal is carried into the interior of the muscle cell via the membranes of the:
a. Intercalated disks
b. Nuclear envelope
c. Sarcomere
d. Sarcoplasmic reticulum
e. T-tubules
ANS: E
T-tubules form membranous invaginations of the sarcolemma that communicate electrical im-pulses to the sarcoplasmic reticulum. The sarcoplasmic reticulum responds by releasing calcium into the cytoplasm, which triggers muscle contraction.
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