The structure enabling depolarization to travel deep into the muscle fiber is the ________.
A)T tubule
B)sarcoplasmic reticulum
C)motor unit
D)sarcomere

Question

Quizplus · Accepted Answer

T tubules are invaginations of the muscle cell membrane that allow depolarization to quickly penetrate deep into the muscle fiber and trigger the release of calcium from the surrounding sarcoplasmic reticulum, leading to muscle contraction. The sarcoplasmic reticulum stores and releases calcium ions, but it does not enable depolarization to travel deep into the muscle fiber. Motor units are composed of a motor neuron and the muscle fibers it innervates, and sarcomeres are the basic contractile units of muscle fibers. While both are important for muscle function, neither enables depolarization to travel deep into the muscle fiber.

The Structure Enabling Depolarization to Travel Deep into the Muscle