Depolarization can be induced artificially.
The depolarization of muscles refers to changes in the cell membrane potentials that cause the muscles to contract. The membrane potential is the difference in voltage between the exterior and the interior of a cell. Membrane potentials can be depolarized artificially and also by the presence of certain ions within the body.
Hyperkalemia
Hyperkalemia is an abnormally high level of potassium in the blood. Potassium plays an essential role in controlling the activity of the body's smooth, skeletal and heart muscles. High levels of potassium can build up through the body's own failure to eliminate the excess, such as in patients with kidney disorders. The person may urinate or vomit as the body tries other ways to eliminate the potassium. The failure to eliminate excess extracellular potassium can result in the membrane potentials of the body's cells becoming depolarized, leading to impairments of the cardiac, gastrointestinal and neuromuscular organ systems.
Acute Hypoxia
Acute hypoxia is when the amount of oxygen available for the body's tissue to use is suddenly or rapidly depleted. This can result from an obstruction to the airway which limits oxygen intake, asphyxia, acute hemorrhage, cardiorespiratory failure or if the lungs' alveoli are blocked by sudden swelling or fluid production. Alterations to oxygen tension can result in arrhythmic contractions and depolarization. A study of fetuses by the American Journal of Physiology -- Lung Cellular and Molecular Physiology found that acute hypoxia caused membrane depolarization and calcium influx in the pulmonary artery smooth muscle cells. The most obvious symptom of acute hypoxia is hypoventilation.
Electricity
Muscles can be artificially depolarized by applying a low voltage to the nerve that provides the muscle with current. The electrical current causes the muscle to contract. This artificial depolarization can be the basis for therapy that seeks to strengthen the weakened muscles of stroke victims and those suffering from injuries that have led to muscle wastage.
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