Neurons are called excitable cells because they have an electrical potential difference i.e., they are in a polarised state and they quickly stimulate to an electrical disturbance. There is a change in the potential difference and depolarisation or impulses are observed from the input to output region of the neuron which passes on to the adjacent neuron.

The special features of the membrane of the neuron are:

i) During the resting stage of the neuron, it has a sodium-potassium ion pump (i.e., Na⁺- K⁺ ion pump).

ii) If there is a change in potential difference then it is spread to the entire neuron.

iii) Stimulus in normally obtained in a place known as trigger zone in which sodium ions (i.e., Na⁺ ions) are abundantly present.

iv) Neurons are connected to several other adjacent neurons which receive and transmit impulses to various paths collectively.