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Muscle contraction is the activation of tension-generating sites within muscle cells. [1] [2] ... A simplified image showing earthworm movement via peristalsis.
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 actin ( thin filaments ) during muscle contraction, while the two groups of filaments ...
The activation of more motor neurons will result in more muscle fibers being activated, and therefore a stronger muscle contraction. Motor unit recruitment is a measure of how many motor neurons are activated in a particular muscle, and therefore is a measure of how many muscle fibers of that muscle are activated.
There are four main types of muscle contraction: isometric, isotonic, eccentric and concentric. [29] Isometric contractions are skeletal muscle contractions that do not cause movement of the muscle. and isotonic contractions are skeletal muscle contractions that do cause movement. Eccentric contraction is when a muscle moves under a load ...
Cardiac and smooth muscle contractions are stimulated by internal pacemaker cells which regularly contract, and propagate contractions to other muscle cells they are in contact with. All skeletal muscle and many smooth muscle contractions are facilitated by the neurotransmitter acetylcholine .
More than 30 years before the development of the sliding filament model of muscle contraction and the understanding of the relationship between active tension and sarcomere length, Starling hypothesized in 1914, "the mechanical energy set free in the passage from the resting to the active state is a function of the length of the fiber ...
An impulse from a nerve cell causes calcium release and brings about a single, short muscle contraction called a muscle twitch. If there is a problem at the neuromuscular junction, a very prolonged contraction may occur, such as the muscle contractions that result from tetanus. Also, a loss of function at the junction can produce paralysis. [5]
Smooth muscle differs from skeletal muscle and cardiac muscle in terms of structure, function, regulation of contraction, and excitation-contraction coupling. However, smooth muscle tissue tends to demonstrate greater elasticity and function within a larger length-tension curve than striated muscle. This ability to stretch and still maintain ...