ANATOMY

Detailed explanation-1: -As T-tubules bring the sarcolemma very close to the sarcoplasmic reticulum at all regions throughout the cell, calcium can then be released from the sarcoplasmic reticulum across the whole cell at the same time. This synchronisation of calcium release allows muscle cells to contract more forcefully.

Detailed explanation-2: -On excitation, small amounts of Ca2+ enter from the transverse tubule and interact with a Ca2+ enter from the transverse tubule and interact with a Ca2+ receptor at the terminal cisternae and cause Ca2+ release (Ca2+-induced Ca2+ release).

Detailed explanation-3: -SPEG Controls Calcium Reuptake Into the Sarcoplasmic Reticulum Through Regulating SERCA2a by Its Second Kinase-Domain.

Detailed explanation-4: -Calcium is released from the sarcoplasmic reticulum through calcium ion channels when the membrane of the T-tubular system is excited. It binds to Troponin C causing it to conform, hence permitting the myosin head to latch onto the actin filament, onsetting muscle contraction.

Detailed explanation-5: -An action potential moving through a T tubule triggers the release of Ca2+ from SER into the cytoplasm (Fig. 39.14). Ca2+ binding to troponin allows myosin to interact with the thin filament, initiating contraction. This signal transduction process is called excitation–contraction coupling.