Polarisation:
Polarisation refers to the process of creating a difference in electrical charge across a cell membrane. This occurs when there is an unequal distribution of ions on either side of the membrane, resulting in a separation of positive and negative charges. Polarisation is a fundamental process in the generation and conduction of electrical signals in cells.

Depolarisation:
Depolarisation is the reversal of the electrical potential across a cell membrane, leading to a decrease in the voltage difference between the inside and outside of the cell. During depolarisation, the cell membrane becomes more permeable to specific ions, allowing them to move across the membrane. This movement of ions causes the inside of the cell to become less negative compared to the outside.

Repolarisation:
Repolarisation is the process of restoring the electrical potential across a cell membrane back to its resting state after depolarisation. It involves the movement of ions across the membrane, which helps to bring the cell's voltage back to its original negative resting potential. Repolarisation is crucial for the proper functioning of cells and is necessary to allow them to reset and prepare for the next electrical signal.

Key Points:
- Polarisation is the creation of an electrical charge difference across a cell membrane.
- Depolarisation is the reversal of the electrical potential, leading to a decrease in the voltage difference.
- Repolarisation is the process of restoring the electrical potential to its resting state after depolarisation.
- Depolarisation occurs when the cell membrane becomes more permeable to ions, causing the inside of the cell to become less negative.
- Repolarisation involves the movement of ions across the membrane to restore the cell's resting potential.
- These processes are essential for the generation and conduction of electrical signals in cells.

Polarisation is the stage in which the sodium ions move out so that inside becomes positively charged.and reversal of this state is depolarization.the regain of the resting potential is called repolarization