Question

Discuss the role of sodium in the transmission of the nerve impulse.

Answer 1

1. Polarisation (Resting Stage): In the resting stage, the plasma membrane of a neuron maintains a higher concentration of Na⁺ ions on the outer side, giving the outer surface a positive charge and the inner surface a negative charge.
2. Depolarisation (Action Potential): When a stimulus is received, the polarity reverses as Na⁺ ions move across the membrane into the axon. This makes the outer side negatively charged and the inner side positively charged, generating an action potential or nerve impulse.
3. Active Transport via Sodium Pump: The movement of Na⁺ ions across the plasma membrane to alter polarity and transmit the impulse is achieved through active transportation via the sodium pump, which utilises energy obtained from ATP.