a) all ion channels close b) the interior of the cell becomes positively charged

Question

a) all ion channels close

b) the interior of the cell becomes positively charged relative to the outside

c) the cell soon reaches threshold

d) the interior of the cell becomes negatively charged relative to the outside

Examine the figure below regarding how information travels across a neuron. Once an action potential is triggered (step 2), Neuron interior 1 Resting potential A stimulus opens the first set of ion channels; if threshold is reached, an action potential is triggered. 04 The first set of channels 3 Additional channels closes and inactivates; open: in that region of the neuron, the interior second set of channels of the cell becomes more opens and positive ions rush out the membrane positive than the outside. returns to resting potential.

Explanation / Answer

Once an action potential is triggered, (d.) enough depolarization (ie. inward flow of sodium ions and less negative charge inside the cell) accumulates causing a change in electrochemical gradient to bring the membrane potential up to threshold. (c.) This causes more ion channels to open, producing a greater electrical current across the cell membrane and opening of all available ion channels.

Now the rapid influx of sodium ions causes the polarity of the plasma membrane to reverse. The sodium channels close and they are transported back into the plasma membrane. This activates potassium channels to open and there is outward flow of potassium ions, resulting in return of the electrochemical gradient of the cell membrane to resting state and (b) the interior of the cell to be positively charged relative to the outside.

Function of action potential is to activate intracellular processes by playing an important role in cell-to-cell communication.

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