The main function of striated muscle is contraction . Contractions cause nerve impulses that come out from the central nervous system and move by the

Striated muscle contraction [Skeletal]

The main function of striated muscle is contraction. Contractions cause nerve impulses that come out from the central nervous system and move by the motor nerves. The more intense the excitement of motor nerves, the greater the contraction. If the nerves are damaged, the muscle atrophies and becomes unmovable.

Skeletal muscles are never in a state of complete relaxation, and always staying a bit in tonus.

When muscle fibers are excited, a thin (actin) contractile fibers that are oriented parallel to the axis of the muscle, begin to slide along the thick (myosin), without changing the length. This process is provided by calcium ions and the energy of ATP. Muscle length decreases (diagram 36).

After contraction necessarily comes muscle relaxation. Contractile fibers slide in the opposite direction, and muscle length increases.

The strength of contraction with some irritation power depends on the anatomical structure and the physiological state of the muscles. Long muscles contract more than the short. Moderate stretching increases muscle contraction; a strong stretching weakens muscle contractions. Taken from http://worldofschool.org

Diagram 36. The mechanism of muscle contraction: 1 — thin (actin) contractile fibers; 2 — thick (myosin) contractile fibers
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Questions:
  • What is the relationship of muscle contraction with nervous excitement?

  • Explain the physiological mechanism of the muscle fiber excitation.

  • Explain the physiological mechanism of muscles contraction and relaxation. Analyze the relationship between these processes.