Our entire skeletal muscles are composed of many muscle groups or individual muscles. A muscle, in turn, is composed of many muscle fiber bundles.
The skeletal muscles
Presentation and explanation of the functions of a muscle – muscle fiber bundle – muscle fiber – sarcomere – actin-myosin – titin.
Detailed view of a Muscle
The individual muscle fiber bundles of a skeletal musculature with the contained muscle fibers as well as the covering of the muscle with the muscle skin, the so-called fascia, can be recognized here.
The muscle fiber Bundle
A single muscle fiber bundle of our skeletal muscles consists of many individual muscle fibers (also muscle fibrils, myofibrils, see Fig. 3). The muscle fibers can reach a length of up to 15 cm with a diameter of approx. 0.01 mm.
Under the microscope, the stripe-shaped division of the sarcomeres across the musculature can be seen very clearly. Hence the name “striated musculature”.
The muscle fibers (also muscle fibrils, myofibrils) of our skeletal muscles consist of many individual sarcomeres. The sarcomeres consist mainly of two individual structures, the actin filament and the myosin filament, which can slide into each other (= filament sliding) and thus cause contraction (tension) of the muscle (see Fig. 4).
In addition, the molecular biologists Maruyama and Wang first described titin at the end of the 1980s, which plays an essential role for the stability and elasticity of the muscle. Thus the titin as a molecular feather provides among other things for the rest tension of the musculature.
To put it simply, titin can be understood as an antagonist to actin. At rest and when the muscle is stretched, the titin exerts a pull on the Z-band. In a contraction, however, it is the actin that pulls on the Z-band.
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