Question

For the voltage-gated sodium channel to allow sodium into the cell:_______.

Answer 1

Answer:

The correct option is - (a) the activation and inactivation gates must both be open.

Explanation:

Option (a) is correct because of the following reason -

The axonal membrane is at its natural resting potential until an action potential occurs, and $Na^+$ channels are deactivated and blocked on the extracellular side by their activation gates. The activation gates open in response to an electric current, allowing positively charged $Na^+$ ions to flow into the neuron through the channels. When enough $Na^+$ has penetrated the neuron and the membrane potential has reached a certain level, the $Na^+$ channels inactivate themselves by closing their inactivation gates at the height of the action potential. The inactivation gate can be thought of as a "plug" tethered to the intracellular alpha subunit's domains III and IV. When the inactivation gate is closed, the flow of $Na^+$ through the channel is stopped. As a result, both the activation and inactivation gates must be open to enable sodium ions to enter the cell.

Hence , the correct option is (a).