MUSCLE PHYSIOLOGY

Detailed explanation-1: -Calcium ions at rest are stored in the sarcoplasmic reticulum (SR) from which they are rapidly released upon the depolarisation of the sarcolemmal and transverse (T-) tubular membranes of the muscle cell.

Detailed explanation-2: -The sarcoplasmic reticulum in the muscle fibers resembles a network of smooth endoplasmic reticulums. This Sarcoplasmic reticulum functions as a storehouse of calcium iron.

Detailed explanation-3: -The sarcoplasmic reticulum (SR) is a type of smooth endoplasmic reticulum that abounds in the myocyte (muscle cell). In myocytes, it can be seen as a membrane-bound structure inside the myocyte, containing calcium ions.

Detailed explanation-4: -The sarcolemma or cell membrane is the site where calcium enters and leaves the cell through a distribution of ion channels, transporters, and pumps. The T-tubules are invaginations of the sarcolemma that form a permeability barrier between the cytosol and the extracellular space (Brette and Orchard, 2003).