Voltage-Gated Sodium Channels

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What is the primary function of the inactivation gate peptide in sodium channels?

To restore inactivation and block open sodium channels (correct)

To increase the refractory period of the neuron

To decrease the voltage-sensor movement

To activate the sodium channel

What is the result of the movement of the voltage-sensor in Domain IV of sodium channels?

Slow inactivation of the sodium channel

Decreased refractory period of the neuron

Activation of the sodium channel

Fast inactivation of the sodium channel (correct)

What is the role of hydrophobic amino acid residues in sodium channels?

To increase the voltage-sensor movement

To form a cluster required for fast Na+ channel inactivation (correct)

To activate the sodium channel

To decrease the refractory period of the neuron

What is the consequence of the refractory period on the neural code?

It provides a nonlinear gain control to graded potential neurons Signup and view all the answers

What is the clinical significance of measuring the refractory period in peripheral nerve?

It is used to diagnose neural disorders Signup and view all the answers

What is the result of axonal myelination on the action potential refractory period?

It increases the action potential refractory period Signup and view all the answers

What happens to the sodium ions during the repolarization of the membrane?

They are blocked from entering the cell, reducing the membrane potential. Signup and view all the answers

What is the effect of the potassium ions leaving the cell during repolarization?

It decreases the membrane potential. Signup and view all the answers

What happens to the sodium channel's activation gate during repolarization?

It closes, blocking sodium ions from entering. Signup and view all the answers

What triggers the closure of the sodium channel's activation gate during repolarization?

The change in the electric field around the channel. Signup and view all the answers

What is the state of the sodium channel when its activation gate is closed and its inactivation gate is open?

Resting Signup and view all the answers

Why do not all sodium channels inactivate during the action potential?

Some channels are resistant to inactivation. Signup and view all the answers

What is the primary mechanism underlying the transmission of information in neurons?

Ionic currents generated by the opening of voltage-gated channels Signup and view all the answers

What is the function of the activation gate in voltage-gated Na+ channels?

To sense changes in membrane voltage Signup and view all the answers

What is the role of the inactivation gate in voltage-gated Na+ channels?

To rapidly inactivate the channel Signup and view all the answers

What is the structural feature of voltage-gated K+ channels that differs from Na+ channels?

The presence of four identical subunits Signup and view all the answers

What is the final state of a voltage-gated Na+ channel after activation?

Inactivated, with the activation gate open and the inactivation gate closed Signup and view all the answers

What is the significance of the region between domains III and IV in voltage-gated Na+ channels?

It is the site of rapid inactivation Signup and view all the answers