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Muscle contraction is dependent on a 100- to 10,000-times-higher-than-resting intracellular Ca 2+ concentration, which is caused by Ca 2+ release from the muscle cells' sarcoplasmic reticulum. Immediately after muscle contraction, intracellular Ca 2+ is quickly returned to its normal concentration by a carrier enzyme in the plasma membrane, and ...
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]
ATP fuels muscle contractions. [44] Muscle contractions are regulated by signaling pathways, although different muscle types being regulated by specific pathways and stimuli based on their particular function. However, in all muscle types, contraction is performed by the proteins actin and myosin. [45] ATP is initially bound to myosin.
When 2 calcium ions, along with a molecule of ATP, bind to the cytosolic side of the pump (i.e. the region of the pump outside the SR), the pump opens. This occurs because ATP (which contains three phosphate groups) releases a single phosphate group (becoming adenosine diphosphate). The released phosphate group then binds to the pump (in the P ...
It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. [2] Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy. In the neuromuscular system, nerves from the central nervous system and the peripheral nervous system are linked and work together with muscles. [3]
The first muscle protein discovered was myosin by a German scientist Willy Kühne, who extracted and named it in 1864. [7] In 1939 a Russian husband and wife team Vladimir Alexandrovich Engelhardt and Militsa Nikolaevna Lyubimova discovered that myosin had an enzymatic (called ATPase) property that can break down ATP to release energy. [8]
In muscle cells, for example, an action potential is the first step in the chain of events leading to contraction. In beta cells of the pancreas , they provoke release of insulin . [ a ] Action potentials in neurons are also known as " nerve impulses " or " spikes ", and the temporal sequence of action potentials generated by a neuron is called ...
In the peripheral nervous system, Schwann cells respond to nerve stimulation and modulate the release of neurotransmitters through mechanisms involving ATP and adenosine signalling. [37] In the retina and the olfactory bulb, ATP is released by neurons to evoke transient calcium signals in several glial cells such as Muller glia and astrocytes ...