Question

Which allows action potentials to move rapidly from the cell surface into the interior?

terminal cisternae

fascicles

t-tubules

crossbridges

sarcoplasmic reticulum

Answer 1

The T-tubules in the sarcolemma allow action potentials to move rapidly into the interior of the cell, triggering muscle fiber contraction.

Step-by-step explanation:

The T-tubules allow action potentials to move rapidly from the cell surface into the interior of the cell. These T-tubules are periodic invaginations in the sarcolemma, or muscle cell membrane. They carry the action potential into the interior of the cell, triggering the opening of calcium channels in the adjacent sarcoplasmic reticulum (SR). This allows calcium ions to diffuse out of the SR and into the sarcoplasm, initiating muscle fiber contraction.