What does sarcolemma mean?
Definitions for sarcolemma
ˌsɑr kəˈlɛm əsar·colem·ma
This dictionary definitions page includes all the possible meanings, example usage and translations of the word sarcolemma.
an extensible membrane enclosing the contractile substance of a muscle fiber
A thin cell membrane that surrounds a striated muscle fibre
The sarcolemma (sarco (from sarx) from Greek; flesh, and lemma from Greek; sheath) also called the myolemma, is the cell membrane surrounding a skeletal muscle fiber or a cardiomyocyte. It consists of a lipid bilayer and a thin outer coat of polysaccharide material (glycocalyx) that contacts the basement membrane. The basement membrane contains numerous thin collagen fibrils and specialized proteins such as laminin that provide a scaffold to which the muscle fiber can adhere. Through transmembrane proteins in the plasma membrane, the actin skeleton inside the cell is connected to the basement membrane and the cell's exterior. At each end of the muscle fiber, the surface layer of the sarcolemma fuses with a tendon fiber, and the tendon fibers, in turn, collect into bundles to form the muscle tendons that adhere to bones. The sarcolemma generally maintains the same function in muscle cells as the plasma membrane does in other eukaryote cells. It acts as a barrier between the extracellular and intracellular compartments, defining the individual muscle fiber from its surroundings. The lipid nature of the membrane allows it to separate the fluids of the intra- and extracellular compartments, since it is only selectively permeable to water through aquaporin channels. As in other cells, this allows for the compositions of the compartments to be controlled by selective transport through the membrane. Membrane proteins, such as ion pumps, may create ion gradients with the consumption of ATP, that may later be used to drive transport of other substances through the membrane (co-transport) or generate electrical impulses such as action potentials. A special feature of the sarcolemma is that it invaginates into the sarcoplasm of the muscle cell, forming membranous tubules radially and longitudinally within the fiber called T-tubules or transverse tubules. On either side of the transverse tubules are terminal cisternal enlargements of the sarcoplasmic reticulum (termed endoplasmic reticulum in nonmuscle cells). A transverse tubule surrounded by two SR cisternae are known as a triad, and the contact between these structures is located at the junction of the A and I bands.
the very thin transparent and apparently homogeneous sheath which incloses a striated muscular fiber; the myolemma
Etymology: [NL., from Gr. sa`rx, sa`rkos, flesh + rind, skin.]
The sarcolemma, also called the myolemma, is the cell membrane of a skeletal, cardiac, or smooth muscle cell. It consists of a true cell membrane, called the plasma membrane, and an outer coat made up of a thin layer of polysaccharide material that contains numerous thin collagen fibrils. At each end of the muscle fiber, this surface layer of the sarcolemma fuses with a tendon fiber, and the tendon fibers in turn collect into bundles to form the muscle tendons that then insert into bones. The membrane is configured to receive and conduct stimuli. Alterations in the sarcolemma membrane stability and repair system can lead to muscular dystrophy. The mechanism of one type of muscular dystrophy, for example, 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. The sarcolemma invaginates into the cytoplasm of the muscle cell, forming membranous tubules called transverse tubules. Terminal cisternae 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.
Chambers 20th Century Dictionary
sär-kō-lem′a, n. a membrane which invests striped muscular tissue.—adj. Sarcolemm′ic. [Gr. sarx, sarkos, flesh, lemma, a skin.]
U.S. National Library of Medicine
The excitable plasma membrane of a muscle cell. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)
A form of membrane.
Sarcolemma is a form of membrane in a muscle in the human body.
Submitted by MaryC on December 26, 2020
the elastic covering of the striated muscular fibres.
The numerical value of sarcolemma in Chaldean Numerology is: 6
The numerical value of sarcolemma in Pythagorean Numerology is: 1
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