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Damage to skeletal muscle may take various forms. Crush and other physical injuries cause damage to muscle cells directly or interfere with blood supply, while non-physical causes interfere with muscle cell metabolism. When damaged, muscle tissue rapidly fills with fluid from the bloodstream, including sodium ions.
Inactivity and starvation in mammals lead to atrophy of skeletal muscle, accompanied by a smaller number and size of the muscle cells as well as lower protein content. [31] In humans, prolonged periods of immobilization, as in the cases of bed rest or astronauts flying in space, are known to result in muscle weakening and atrophy.
The mitochondria are unable to produce enough ATP to power the cell properly. Reduction in ATP production impairs the cells' ability to extract calcium from the muscle cell. Motor endplate of a person with rhabdomyolysis. The ion imbalance causes calcium-dependent enzymes to activate which break down muscle proteins even further. [8]
Depending on the extent of injury, the cellular response may be adaptive and where possible, homeostasis is restored. [1] Cell death occurs when the severity of the injury exceeds the cell's ability to repair itself. [2] Cell death is relative to both the length of exposure to a harmful stimulus and the severity of the damage caused. [1]
As a result, there is a decrease in amplitude and velocity of impulse conduction with an increase in muscle spike duration. [ 18 ] In clinical and experimental studies there is an observed increase in muscle excitability in electrical currents involving chemical actions, while there is a decrease in excitability to current associated with ...
Progressive muscular atrophy (PMA), also called Duchenne–Aran disease and Duchenne–Aran muscular atrophy, is a disorder characterised by the degeneration of lower motor neurons, resulting in generalised, progressive loss of muscle function.
Deficiency of BNIP3 leads to muscle inflammation and atrophy. [19] Furthermore, not every muscle is as susceptible to the atrophic effects of aging. For example, in both humans [20] and mice [21] it has been shown that lower leg muscles are not as susceptible to aging as upper leg muscles. This could perhaps be explained by the differential ...
This usually starts with the observation of bulk, possible atrophy or loss of muscle tone. Neuromuscular disease can also be diagnosed by various blood tests and using electrodiagnostic medicine tests [ 23 ] including electromyography [ 24 ] (measuring electrical activity in muscles) and nerve conduction studies . [ 25 ]