Muscle contraction is the activation of tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. The termination of muscle contraction is followed by muscle relaxation, which is a return of the muscle fibers to their low tension-generating state.
Hierarchical organization of skeletal muscle
Contractions of skeletal muscles allow vertebrate animals such as frogs to move
Types of muscle contractions
Organization of skeletal muscle
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over 100 μM; its mass is roughly 42 kDa, with a diameter of 4 to 7 nm.
Fluorescence micrograph showing F-actin (in green) in rat fibroblasts
Structure of the C-terminal subdomain of villin, a protein capable of splitting microfilaments
Giant nemaline rods produced by the transfection of a DNA sequence of ACTA1, which is the carrier of a mutation responsible for nemaline myopathy
Position of seven mutations relevant to the various actinopathies related to ACTA1
