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Electromechanical interface in muscles
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Electromechanical interface is the cycle of consecutive processes beginning occurrence of potential of action on sarcolemma (a cellular membrane) and coming to an end retractive answer of a muscle.
Infringement of sequence of processes of interface can lead to pathologies and even by a lethal outcome. The basic stages of this process can be tracked on fig. 10
In cardiac hystiocyte electromechanical interface goes in two steps: in the beginning the small entering stream of calcium activates membranes of sarcoplasmic reticulum, promoting the big emission of calcium from endocellular depot, and then as a result of this emission there is a reduction of sarcomere. The described two-level process of interface is proved experimentally. Experiences have shown, that: absence of a stream of calcium from the outside cells stops reduction of sarcomere, in conditions of a constancy of quantity of the calcium liberated from sarcoplasmic reticulum, change of amplitude of a stream of calcium leads to well correlating change of force of reduction. The stream of ions 
inside of a cell carries out thus two functions: forms long (200 msec) a plateau of potential of action of cardiac hystiocyte and participates during electromechanical interface.
In skeletal muscles potential of action short (2-3 msec) and the slow stream of ions of calcium in them is absent. In these cells the system of the cross-section tubules suitable directly to sarcomeres is strongly developed Т-, is close to z - to disks (fig. 11). Changes of potential of a membrane during depolarization through Т - system it is transferred in such cells directly to membrane of sarcoplasmic reticulum, causing fast liberation of ions and the furt her activation of reduction.
Electromyography - a method of electrophysiological diagnostics of defeats of the nervously-muscular system, consisting in registration of electric activity (biopotentials) of skeletal muscles.
Distinguish spontaneous electromyography, reflecting a condition of muscles in rest or at a muscular pressure, and also the caused muscles caused by electric stimulation or a nerve.
needle electrodes superficial electrodes
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