Sarcoplasm

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sarcoplasm

[′sär·kə‚plaz·əm]
(histology)
Hyaline, semifluid interfibrillar substance of striated muscle tissue.

Sarcoplasm

 

the cytoplasm of smooth-muscle cells and striated and myocardial muscle fibers. The matrix, or basic material, of sarcoplasm contains glycolytic enzymes and other globular proteins, for example, myoglobin; it also contains salts, polyphosphates, and glycogen, which is depleted during muscle contraction. Sarcoplasm surrounds nuclei and fills the space between myofibrils. It contains ribosomes, mitochondria (sarcosomes), and a complex system of membrane-bound vesicles, tubules, and cisterns, all of which are combined into a continuous sarcoplasmic reticulum.

The sarcoplasmic reticulum is divided into two parts. One part is oriented along the myofibrils and is equivalent to the endoplasmic reticulum found in other types of cells. The other part is oriented across a muscle fiber and forms the T system, which is a system that conducts impulses from the surface to deep within a muscle fiber and, in some places, changes into sarcolemma. The sarcoplasmic reticulum probably transmits excitation within a fiber. It also contains the Marsh factor, which inhibits the activity of the enzyme adenosine triphosphatase. The amount of sarcoplasm varies in different striated fibers: collagenous fibers contain little sarcoplasm, whereas red fibers contain a great deal.

L. V. DANILOVA

References in periodicals archive ?
2001) Sarcoplasmic reticulum function and muscle contractile character following fatiguing exercise in humans.
Mechanism of nitric oxide-induced vasodilatation: refilling of intracellular stores by sarcoplasmic reticulum Ca2+ ATPase and inhibition of store-operated Ca2+ influx.
Besides, the patient's cardiomyocytes had a lower content of calcium ions in the sarcoplasmic reticulum, which suggested its possible abnormal leakage [47].
Histidine-containing dipeptides as endogenous regulators of the activity of sarcoplasmic reticulum Ca-release channels.
Delineation of three different thyroid hormone-response elements in promoter of rat sarcoplasmic reticulum Ca2+-ATPase gene.
Increased nitration of sarcoplasmic reticulum Ca2+-ATPase in human heart failure.
Overall, most of the identified proteins were grouped as myofibrillar proteins, which responsible in structural integrity of skeletal muscle while creatine kinase and myoglobin were grouped as sarcoplasmic proteins.
Consequently, this high concentration of Na+ increases the exchange of Na+ by the sarcoplasmic [Ca.
Effect of taurine on sarcoplasmic reticulum function and force in skinned fast-twitch skeletal muscle fibres of the rat.
Anatomic specialization within the t-tubule is seen at the triad where the t-tubule is flanked by the calcium storage organelle, the sarcoplasmic reticulum.