How does an action potential spread rapidly to the central portions of a muscle cell

Question

Quizplus · Accepted Answer

Action potential spreads rapidly to the central portions of a muscle cell by means of T tubules, which are invaginations of the sarcolemma (muscle cell membrane) that reach deep into the muscle fiber. The T tubules facilitate the depolarization of the muscle fiber by allowing the action potential to penetrate deep into the fiber, triggering the release of calcium ions from the sarcoplasmic reticulum, which leads to muscle contraction.

How Does an Action Potential Spread Rapidly to the Central