The propagation of nerve impulse is explained by the so called "local circuit theory". The membrane becomes depolarized at the point of stimulation and hence acts as a "sink", towards which the current flows from the adjacent areas. this results in conduction or passage of nerve impluse. Conduction of impluse is of two types- (i) continuous conduction and (i) saltory conduction.
(i) Continuous conduction : In this type of impulse propagatioon, there is step by step depolarisation and repolarisation of each adjacent segment of the plasma membrane. therefore it is called continuous conduction. It occurs in unmyelinated axons.
(ii) Saltatory nerve conduction : This is a special mode of impulse propagation along myelinated axons, in which nerve impulse "leaps" from one node to the other ("Saltatory means leaping").
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