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Depiction of smooth muscle contraction. Muscle contraction is the activation of tension -generating sites within muscle cells. [ 1][ 2] 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. [ 1]
Interactive animation of the structure of ATP. Adenosine triphosphate ( ATP) is a nucleotide [ 2] that provides energy to drive and support many processes in living cells, such as muscle contraction, nerve impulse propagation, and chemical synthesis.
A main component in the cytoskeleton that helps show the true function of this muscle contraction is the microfilament. Microfilaments are composed of the most abundant cellular protein known as actin. [10] During contraction of a muscle, within each muscle cell, myosin molecular motors collectively exert forces on parallel actin filaments.
Sliding filament theory: A sarcomere in relaxed (above) and contracted (below) positions. The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement. [ 1] According to the sliding filament theory, the myosin ( thick filaments) of muscle fibers slide past the ...
A tetanic contraction (also called tetanized state, tetanus, or physiologic tetanus, the latter to differentiate from the disease called tetanus) is a sustained muscle contraction [2] evoked when the motor nerve that innervates a skeletal muscle emits action potentials at a very high rate. [3] [4] During this state, a motor unit has been ...
Since smooth muscle does not contain a troponin complex, as striated muscle does, this mechanism is the main pathway for regulating smooth muscle contraction. Reducing intracellular calcium concentration inactivates MLCK but does not stop smooth muscle contraction since the myosin light chain has been physically modified through phosphorylation ...
The action of myosin along the actin filaments causes the shortening and lengthening of the sarcomere; responsible for muscle contraction and relaxation, respectively. Motor proteins are the driving force behind most active transport of proteins and vesicles in the cytoplasm.
Myosins ( / ˈmaɪəsɪn, - oʊ -/ [1] [2]) are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are ATP -dependent and responsible for actin -based motility. The first myosin (M2) to be discovered was in 1864 by Wilhelm Kühne.