Sarcoplasmic reticulum is the SER of striated muscle cells, specialized to sequester calcium ions.
The sarcoplasmic reticulum in cardiac muscle fibers is less organized than that of skeletal muscle and does not subdivide myofila ments into discrete myofibrillar bundles.
Mechanism of Contraction: Although the arrangement of the sarcoplasmic reticulum and T tubule complex of cardiac muscle fibers differs from that of skeletal muscle, the composition and arrangement of myofilaments are almost identical.
That is, the SR membrane contains Ca pump that transports Ca from the sarcoplasm into the SR lumen at the expense of ATP.
It forms a network in the sarcoplasm so that each fiber is surrounded by the reticulum and thereby has easy access to Ca The SR widens at its two ends forming terminal sacs, called cisternae.
Within the SR, Ca is bound to calsequestrin, a protein that is anchored to the inner membrane of the terminal cisternae.
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Most of the rhodanese activity of liver has been found in the mitochondria4.
Calf cardiac muscle was homogenized in 0-88 M suc rose5 and three fractions were NH2 obtained by differential cennuclear residue, (b) sarcosomes and (c) sarcoplasm.
Rhodanese activity was estimated by the method of Cosby and Sumner6.
Swollen terminal cisternae or sacs of the sarcoplasmic reticulum are associated with the T-tubules.
In general the sarcoplasmic reticulum of cardiac muscle fiberes is much less well developed than that of myofibers of skeletal muscle.
In cross section, the smooth muscle fibers are seen to form an orderly mosaic of circles of varying diameters, with the nuclei being seen only in fibers sectioned at their widest region.
Then there is sarcoplasmic, this shows much bigger size increase and is due to the increase of sarcoplasm (a fluid) in and around the muscle cells.
Now assuming the atrophy or this muscle loss is a loss of sarcoplasm this could be why we have this seeming miracle of muscle memory.
I think that the loss of sarcoplasm can be quickly reversed and happens when we start exercising again in the "body builders rep range" and the muscles “fill up” with sarcoplasm again and so the size and weight returns to the muscle.
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The energy in the sarcoplasm and fresh supply from the blood is where our recovery components ′come from′.
Also, a false upper limit to size can be reached, eventually the fibers cannot support even the energy requirements for a workout with the proportionally lower quantity of sarcoplasm.
He also is making the distinction between just mitochondria growth and "sarcoplasmic hypertrophy" almost like mitochondria are just a peice of it.
In the noncardiac myocytes (NM) the staining is widely dispersed in the cytoplasm.
In the cardiac myocytes, characterized by a centrally localized circular nucleus (occasionally they are binucleated), positive labeling is observed in the sarcoplasm.
During spreading the myofibrils (arrows) (G,H) are disassembled and nascent myofibrils emerge in the periphery of the sarcoplasm (arrowheads) (H–M).
It is also important to know the anatomical relationship between the sarcoplasmic reticulum (which holds Ca++ “outside” of the sarcoplasm) and the T-tubules, which are invaginations of the cell membrane.
The myofibrils are surrounded by a network of endoplasmic reticulum, the sarcoplasmic reticulum (SR).
Then, a complicated process that involves a Ca++ channel on the SR membrane (the “ryanodine receptor”) and a voltage-gated channel of the T-tubule membrane (the “dihydropyridine” receptor), the depolarization of the T-tubule leads to a massive influx of Ca++ from the SR in to the sarcoplasm.
The skeletal muscle is made of a group of fascicles [pack of cells] that hold inside the muscle cells [also named muscle fibers, because their cylindrical structure].
Its plasma membrane is named sarcolemma [sarco-, flesh], its cytoplasm is named sarcoplasm, and its endoplasmic reticulum is named sarcoplasmic reticulum [SR].
The muscle cell is made of a pack of smaller cylinders named myofibrils [myo-, muscle].
OkCupid! sarcoplasm / 35 / m / straight / San Diego, California, United States(Site not responding. Last check: 2007-10-09)
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It looks like sarcoplasm hasn't made any journal entries.
Maybe you should send him a kooky message and encourage him to post one.
A fine reticular network of membrane-limited elements that pervades the sarcoplasm of a muscle fiber; continuous over large portions of the cell and with the nuclear envelope; an endoplasmic reticulum specialized for the sequestration of calcium ions.
See also the cellular component terms 'sarcoplasm ; GO:0016528', 'nuclear envelope ; GO:0005635' and 'endoplasmic reticulum ; GO:0005783'.
