Question

7-During hyperpolarization: a- Potential difference returns to -70mv b-More sodium ions move from outside the neuron to inside the neuron c-More potassium ions move from outside the neuron to inside the neuron d-Sodium and potassium ions return to their initial places e-None of the above

Answer 1

ANSWER- The correct option is e (none of the above). During hyperpolarization ,more potassium ions move from inside the neuron to outside the neuron in continuation with repolarization. So, hyperpolarization is characterized by the movement of more potassium ions from inside the neuron to outside the neuron .It is also characterized by influx of chloride ions i.e. movement of chloride ions from outside the neuron to inside the neuron.

Explanation-

• ​​​​Option a (potential difference returns to -70mv) is incorrect. -70mvp difference is resting potential , during hyperpolarization potential difference decreases more than -70mv .
• Option b ( more sodium ions move from outside the neuron to inside the neuron ) is incorrect as sodium channels are inactived during repolarization and remains closed also during hyperpolarization and no sodium ions move from outside the neuron to inside the neuron.
• Option c ( more potassium ions move from outside the neuron to inside the neuron )is incorrect because during repolarization potassium channels are open but potassium ions move from inside the neuron to outside the neuron and the same movement of potassium ions happens during hyperpolarization.
• Option d (sodium and potassium ions return to their initial places ) is incorrect because when sodium and potassium ions return to their initial places, the stage is called resting stage and this does not happens in hyperpolarization.

Hence, option e (none of the above) is correct.