Title: T-Tubule - an overview | ScienceDirect Topics
Headings: T-Tubule
T-Tubule
Ion Channel Trafficking
T-Tubules
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Muscles
Coupling Action Potentials to Contraction
The Cellular Basis of Cardiac Contractility
The SR Releases Stored Ca 2+ to Activate Contraction
Disorders of Muscle Excitability
Calcium couples muscle membrane excitation to filament contraction
Muscle physiology
Excitation–contraction coupling
EXERCISE | Muscle
Voltage-dependent Sarcoplasmic Reticulum Ca 2+ Release

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Figure 53.2. The SR, seen after Golgi “staining” (A) and in standard thin section (B), forms a complex, continuous network that surrounds the myofibrils. In these fibers from the frog the T-tubules (vertical arrows in B) are located at the Z-lines. The junctional domains of the SR (jSR, oblique arrows) are wide, contain calsequestrin and directly face the T-tubules. The triads are the sites of calcium release during muscle activation and thus they are also called calcium release units (CRUs). The SR appears to be divided into segments by the presence of T-tubules in triads. However, some longitudinal continuity, allowing equilibration of the luminal content through the length of the fiber, is provided by small connections that bypass the interruption introduced by the presence of the T network (arrow in Figure 53.2A ). Thus the SR constitutes a reservoir of calcium whose content is equilibrated through the fiber. View chapter Purchase book
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URL: https://www.sciencedirect.com/science/article/pii/B9780123815101000533
Structure and Function of Calcium Release Channels
Clara Franzini-Armstrong, in Current Topics in Membranes, 2010
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
A disordered arrangement of T tubules, with loss of the precise transverse orientation of the network is a common result of a variety of muscle pathologies.