Which of the following correctly states the direction follow

Which of the following correctly states the direction followed by the specified ions when their voltage-gated channels open?

A. Both Na+ and K+ ions move in.

B. Na+ ions move into the axon; K+ ions move out.

C. Both Na+ and K+ ions move out.

Membrane potential (mV) /) +30 -55 :- 70 Time (ms)

Solution

B. Na+ ions move into the axon; K+ ions move out.

Justification: when sodium gated channels are open, sodium ions will move into the axon resulting in depolarization.

As the potential nears +30mV, the rate of depolarisation slows down as the voltage gated Sodium channels become saturated and inactivate, preventing further sodium ions from entering the cell.

As a result, Voltage gated potassium channels open, and potassium leaves the axon cell down its concentration gradient. The depolarisation of the cell stops and repolarisation can occur through these voltage gated Potssium channnels.