How the action potential is created:

Question 1

Prior to the action potential (during the resting potential):

Answer 1

1) Leakage K+ Channels let potassium out.
2) All Gated Na+ Channels are shut.
3) All Gated K+ Channels are shut.

Question 2

Gated sodium channels open, letting Na+ enter the cell. This causes the RP to change from -70 mV to +20 mV.

Answer 2

Depolarization Phase

Question 3

Gated sodium channels close. Gated potassium channels open, letting K+ exit the cell. This causes the AP to end—the voltage returns down to the RP (-70mV).

Answer 3

Repolarization Phase

Question 4

Gated K+ channels remain open, causing the RP to dip below -70 mV. This phase occurs because too much K+
leaves the cell.

Answer 4

Hyperpolarization