I am a Post graduate Biology teacher.My earlier question wasn't answered under the pretext that it was a home work question.
some links say that transmission of nerve inpulse along the axon is uniderictional due the the occurance of refractory period.But from the diagramatic illustration and from the content given in Medical physiology(Guyton), it is clear that the transmission has to be bidirectional. in such a situation, what would happen to the polarity of neuronal membrane at the region of the dentrites.will transmission of impulse take place from dentrites to axon terminals.

Any nerve if artificially (exogenously) stimulated electrically has the protential for the impulse to be transmitted in both directions. But the endogenous transmission of a nerve inpulse along the axon is indeed unidirectional.