MICROANATOMY

Detailed explanation-1: -The lumen of the smooth ER also serves as an important storage site for intracellular Ca2+.

Detailed explanation-2: -In skeletal muscle cells, SER occurs as a specialized membrane structure known as the sarcoplasmic reticulum. The sarcoplasmic reticulum is a critical storage site for calcium ions, taking up the ions from the cytoplasm.

Detailed explanation-3: -Calcium Store The role of the smooth endoplasmic reticulum in calcium ion storage and release is of particular importance in the cells of the nervous and muscular system that use calcium-mediated signaling for excitation and contraction.

Detailed explanation-4: -The ER is a multifunctional organelle that serves as the most important Ca2+ store in the cell. This organelle is able to accumulate Ca2+ at mM levels in both free and protein-buffered forms (Mekahli et al., 2011; Pozzan et al., 1994; Prins and Michalak, 2011).