Question

If we open a sodium channel, give two reasons why positive sodium ions flow through the membrane into the cell?

Answer 1

Sodium influx:

1. Voltage-gated sodium channels create a pore in the cytoplasmic membrane when they are in the open state, allowing sodium ions to enter the cell and depolarizing it to cause the upstroke of the action potential.
2. However, at depolarized potentials, the majority of sodium channels quickly transition into the "inactivated" state.
3. In this instance, positive Na+ ions enter cells across the membrane for two reasons.
4. Positive ions are drawn within negatively charged cells thanks to the resting potential.
5. Since there are considerably more sodium ions present outside than within, there is an attractive concentration gradient for sodium.