Complete the sentences describing the events that occur during an action potenti

Question

Complete the sentences describing the events that occur during an action potential. An action potential will not occur unless the membrane potential at the _____ (the initial segment of the axon) reaches a level called _____ When threshold is reached, _____ of the initial segment open briefly, allowing _____ to diffuse into the cell. As these ions enter the cell, the cell membrane undergoes _____, with the membrane potential increasing to a peak of approximately +30mV. As the peak of the action potential is reached, the sodium channels close and the ____ open, allowing these ions to diffuse out of the cell. As cations leave the cell, the membrane potential at that part of the membrane is reestablishing resting membrane potential. This phase of the action potential is called _____. The membrane potential actually dips lower than -70mV because the potassium channels do not close quickly enough. This phase is called _____.

Explanation / Answer

Answers:

1) The action potential will not occur unless the membrane potential at the voltage-gated sodium channel reaches a level called threshold.

2)When threshold is reached voltage-gated sodium channel opens briefly allowing sodium to diffuse to the cell.

3) At these ions enter the cell the cell membrane undergoes depolarization with a membrane potential increasing to a peak of approximately +30mV.

4)At the peak of the action potential is reached the sodium channel closed and voltage gated potassium channel opens allowing these ions to diffuse out of the cell.

5)As cations leave the cell, the membrane potential at that part of the membrane is reestablishing resting membrane potential. This phase of the action potential is called repolarization

6)the membrane potential actually dips lower than -70mV because the potassium channel do not close quickly enough. this phase is called hyperpolarization.

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