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Encyclopedia > Sarcolemma
Muscle system
Muscle system

The sarcolemma is the cell membrane of a muscle cell. The membrane is designed to receive and conduct stimuli. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Look up cell membrane in Wiktionary, the free dictionary. ...


Alterations in the sarcolemmal membrane stability and repair system can lead to muscular dystrophy. The mechanism of muscular dystrophy is lack of functional dystrophin. This means that the sarcolemma is not attached to the cytoskeleton. Therefore during muscle contraction, the sarcolemma is not synchronized with the interior of the cell. The looseness of the sarcolemma permits membrane calcium channels to open. The rise in internal calcium ions causes activation of the proteolytic enzyme calpain, which digests proteins including contractile proteins, rendering the muscle much weaker. Muscular dystrophy refers to a group of genetic, hereditary muscle diseases that cause progressive muscle weakness. ... Dystrophin is a protein found in membranes surrounding individual muscle fibers, and its deficiency is one of the root causes of muscular dystrophy. ... The eukaryotic cytoskeleton. ... Ion channels are present in the membranes that surround all biological cells. ...


The sarcolemma invaginates into the cytoplasm of the muscle cell, forming membranous tubules called transverse tubules (t-tubules). Sarcoplasmic reticulum is the enlargement of smooth endoplasmic reticulum found in muscle cells on either side of the transverse tubules. The triad of transverse tubules surrounded by two smooth ER cisternae transmit altered membrane permeability down the tubules. The nuclei lie just adjacent to the sarcolemma, at the periphery of the fiber. Also called transverse tubules, t tubules are deep invaginations of the plasma membrane found in skeletal and cardiac muscle cells. ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ...


This membrane is extensible and encloses the contractile substance of a muscle fiber.


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