Asked in Heart

What is the effect of potassium levels on heart contractions?


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Potassium when released from the cytosol of the autonomic cells (SA AV nodes) into the ECF decreases the slope of the spontaneous depolerization and a hyperpolerization of the membrane potential such that the threshold for an action potential is reached more slowly. The frequency of action potentials is thereby decreased. Decreasing the action potential frequency decreases the speed of impulse conduction, which increases the delay of conduction between atria and ventricles and lengthens the time required for impulse to travel through ventricles. As a result the duration of systole (isovolumeric contraction) increases.