Basal electrical rhythm

The Basal electrical Rhythm (BER) determines the frequency of the contractions in the GI tract.

The Interstitial Cells of Cajal are pacemaker cells located in the GI tract wall. These cells have a rhythmic depolarisation from -65mV to -45mV and then repolarises back to -65mV. This depolarisation - repolarisation creates the slow wave BER. The frequency of these depolarisation determines the possible frequency of contractions. The physical contractions of the smooth muscle are caused by Action Potentials. The actions potentials occur when the BER slow waves reach the threshold (an absolute value less than -45mV) and action potential occurs. The actions potentials can only occur when a depolarisation occurs in the BER. The number of Action Potentials on a BER slow wave can vary and the more action potentials that occur the greater the muscle tension.

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