relaxation of skeletal muscle

Definition

Target type: biologicalprocess

A process in which the extent of skeletal muscle tissue contraction is reduced. Muscle relaxation involves the removal of calcium from the cytoplasm to the sarcoplasmic reticulum lumen through the action of Ca2+ ATPases. [GOC:BHF, GOC:rl]

Relaxation of skeletal muscle is a complex process that involves the removal of calcium ions from the sarcoplasm, the return of the thin filaments to their resting position, and the cessation of muscle contraction.

1. **Calcium Ion Removal:** The sarcoplasmic reticulum (SR), a network of membrane-bound sacs within muscle fibers, actively pumps calcium ions (Ca2+) back into its lumen. This decrease in intracellular Ca2+ concentration is critical for relaxation.
2. **Troponin-Tropomyosin Complex:** As Ca2+ levels drop, the troponin-tropomyosin complex on the thin filaments shifts back to its resting position. This movement blocks the binding sites on actin for myosin heads.
3. **Myosin Detachment:** With the binding sites blocked, myosin heads can no longer attach to actin. This prevents further cross-bridge cycling and muscle contraction.
4. **Elastic Recoil:** The elastic components within the muscle fiber, such as titin and the connective tissue surrounding the muscle, help to pull the sarcomeres back to their resting length.
5. **Muscle Relaxation:** The combined effect of these processes results in muscle relaxation, where the muscle returns to its original length and tension decreases.

In summary, the removal of Ca2+ from the sarcoplasm, the blocking of myosin binding sites on actin, and the elastic recoil of muscle components lead to the cessation of muscle contraction and the relaxation of skeletal muscle.'
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Proteins (1)

Compounds (4)