Which of these structures is part of a muscle cell's plasma membrane that delivers signals to the sarcomere?

Question

Quizplus · Accepted Answer

T-tubules are invaginations of the plasma membrane that run deep into the muscle cell, bringing signals from the motor neuron to the sarcomere. This allows for efficient and coordinated muscle contraction. Myosin heads and actin fibers are both part of the sarcomere itself, while the endoplasmic reticulum is important for calcium ion storage and release, but not for direct signaling to the sarcomere.

Which of These Structures Is Part of a Muscle Cell's