[Campbell Biology P.1123] According to the text, what is the primary function of the 'inactiv... | Practice Question

According to the text, what is the primary function of the 'inactivation loop' associated with voltage-gated sodium channels?

  • A: To increase the rate of Na+ influx during the rising phase.
  • B: To maintain the resting potential by keeping Na+ channels closed.
  • C: To block ion flow through the open channel, leading to inactivation, until the membrane returns to resting potential.
  • D: To facilitate K+ outflow during the falling phase of the action potential.

Explanation

The first paragraph clearly states that the inactivation loop 'blocks ion flow through the open channel' and that 'Sodium channels remain inactivated until after the membrane returns to the resting potential and the channels close.' This mechanism is crucial for the repolarization of the membrane and the refractory period.