Sarcomere


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sarcomere

[′sär·kə‚mir]
(histology)
One of the segments defined by Z disks in a skeletal muscle fibril.

Sarcomere

 

a muscle-fiber segment between two dark Z bands that is the main recurring structural unit of myofibrils. Each sarcomere includes a single dark anisotropic A band and two light isotropic I disks. In the middle of each sarcomere is a narrow light H band containing a dark central M band.

References in periodicals archive ?
In developing the technology, scientists analyzed how sarcomeres generate tension coupled with alterations in calcium cycling, which is critical to heart function.
Scanning electron microscopy analysis showed structure damage of sarcomere Z-disks and presence of pleomorphic dense structures near Z-disks or between myofibrils.
2+] concentrations activates calpains 1 and 2 (Cap-1 and Cap-2), which in turn promote sarcomere disintegration and myofibrillar proteins liberation.
Myofiber disarray is displayed by disordered myocyte bundles, individual myocytes, and contractile elements within sarcomeres.
Objectives: (1) To see whether movement of Z discs on either side of A band toward the center of a sarcomere is possible when contraction is occurring in two adjacent sarcomeres simultaneously.
It is mainly caused by mutations in genes encoding sarcomere proteins (7-10).
A number of peripheral factors prevent the activity of masticatory muscles from being pushed towards both sides by the motor unit, such as the presence of a preferred masticatory side, occlusal stability, food size and consistency, and mandible orientation, which is in turn related to the length of the sarcomere muscle.
Critical to this process is ATP hydrolysis that provides energy for the enzymatic activity of the myosin head which generates a single articulation of the myosin head and molecular movement of actin past myosin which shortens the sarcomere.
We previously established that, using skinned muscle fibers placed in a Ca buffer, each sarcomere exhibited stable auto-oscillation of contraction and elongation under the fixed Ca concentration of approximately 1 uM, through careful measurements of muscle fiber tension (especially using thin bundles of myofibrils ~1 um in diameter); we termed this phenomenon as spontaneous oscillatory contraction (SPOC) (see recent review by S.
The literature describes several viscoelastic properties of skeletal muscle (stress relaxation, creep, and hysteresis) that may explain increased sarcomere compliance and the lengthening process, but there is still some debate as to how much of the change is mechanical/structural and how much is functional/neurological (3), (4).