The mechanism of neuron depolarisation and repolarisation is summarised in easy points below -

1. Nerve impulses causes movement of ions across the cell membrane of a neuron. 

2. The cell membrane of a neuron contains thousands of tiny passage proteins for transport of sodium and potassium in and out of the neurons. These are called Sodium and Potassium Gates.

3. These gates allow either Sodium or Potassium ions to pass through.

4. In the resting stage, these gates on a neuron are closed.

5. A nerve impulse is conducted when pressure or other sensory inputs disturbs a neurons plasma membrane, causing sodium gates to open.

6. At the beginning of an impulse, the sodium gates open, allowing positively charged Na+ ions to flow inside the cell membrane.

7. The inside of the membrane temporarily becomes more positive than outside. 

8. The membrane is now depolarised. 

9. As the impulse passes, the potassium gates open, allowing positively charged K+ ions to move out of the cell. Thus, the inside of the axon resumes a negative charge.

10. The membrane is now said to be repolarised. 

11. The depolarisation and repolarisation events of a neuron membrane is called an action potential.