Biology II - Nervous System: Action Potential Process

Biology II

what are the four stages

resting potential, depolarization, repolarization, and refractory period

resting potential

inside axon is negative (-70 mV)

sodium and potassium channels are closed

more potassium inside cell than outside cell

less sodium inside cell than outside cell

depolarization

impulse moves trough axon and sodium channels open

sodium rushes inside the axon to reach equalibrium (no gradient)

the rush in of sodium causes the inside of the cell to become positive (+30 mV)

repolarization

sodium channels close and potassium channels open

potassium rushed out of the cell to reach equalibrium (no gradient)

rush out of potassium causes inside cell to become negative (-70 mV)

no more gradients

refractory period

sodium and potassium channels are closed because there are no gradients

sodium-potassium pump opens using ATP to restore the gradients

sodium rushes out and potassium rushes in, restoring axon to resting potential (-70 mL)