Why are neurons called excitable cells ? Mention special features of the membrane of the neuron .

Explanation

Neurons are called excitable cells because these can be excited (depolarised) by a stimulus of proper strength. Special features of membrane of neurons are:
(i) Neuronal membrane is electropositive on outside and electronegative on inner side. In a polarised neuron, a rest potential of -90 mV is present.
(ii) Different types of ion-channels are present.
(iii) There is more `Na^+` in extra neuronal fluid and more `K^+` in the neuroplasm.