Muscle contraction is the process whereby the muscle is contracted. Histologically, the muscle tissue is composed of muscle fibers that are polynuclear, elongated cells. The cells in turn contains muscle fibers constructed of sarcomeres. A sarcomer is composed of actin filaments (thin filaments), myosinfilament (thick filaments) with several proteins.
The students who are trying to prepare a good essay on muscle construction have to understand that during the movements of the skeletal muscles, the movement can be consciously controllable or non consciously controllable, the neurological difference lies in the nerve impulse that initiates where the movement comes from. Involuntary movements are also called reflexes.
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To initiate a contraction, a nerve impulse must reach the muscle. This releases calcium ions from the sarcoplasmic reticulum (SR) that can bind to a protein complex with three different types of troponin. This means that another protein, tropomyosin, is moved from its rest position and allows actin and myosin to bind to each other. The contraction requires energy in the form of ATP (adenosine triphosphate). Through a process called cross brewing cycle actin and myosin can then “climb” on each other and thus contract the sarcomeres (and therefore the whole muscle).
The muscle contraction may be in different ways:
- Static contraction (also called isometric contraction): Contraction in which the muscle produces force without motion. This results in an increase in muscle strength, but only in the joint in question.
- Dynamic contraction (there are several types of contraction):
- Concentric: contraction in which the muscle strength makes the muscle shortens;
- Eccentric: muscle contraction extends the muscle;
- Isokinetic: contraction of the muscle at a constant speed, possible only with equipment, not manually;
- Isotonic: contraction of the muscle at constant muscle tension;
In the heart’s muscle contractions, as well as in the rest of the body’s muscle contractions, calcium ions play a special role. Thus, it is generally a biological process by which mechanical forces in muscle are generated. In case of the skeletal muscles, these forces are transmitted through the bone tendon.
The forces are produced by conversion of chemical energy to mechanical by means of the actin-myosin complex in the individual muscle cells, in turn, the source of the chemical energy is the hydrolysis of ATP.
Thus, to ensure a contraction of the muscle tissue as a whole part, and the transmission of power generated in the process, it is necessary to synchronize and coordinate the contraction of the muscle (fiber) cells and a transfer of the force generated by each of muscle fibers to the tendon in question.
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