These components are connected by a series of proteins that control calcium release
Invaginations of the plasma membrane (sarcolemma) of the muscle fibres are called T or transverse tubules
The two terminal cisternae of the sarcoplasmic reticulum (SR) together with their associated T tubule are known as a triad
Inside the muscle fiber, the T-tubules lie next to the terminal cisternae of an internal membrane system derived from the endoplasmic reticulum, called the sarcoplasmic reticulum (SR) which is a store of calcium ions
Stimulation of the muscle fiber, causes a wave of depolarization to pass down the t-tubule, and the SR to release calcium ions into the sarcoplasm
Calcium is pumped back up into the SR to lower calcium ion concentration in the sarcoplasm, to relax the muscle (turn off contraction)
