action vs graded potentials

action potential

begin at the axon hillock

both

hyperpolarization or depolarization can occur

graded potential

brief localized changes in membrane potential

action potential

propagated along axon of a neuron

both

depolarization caused by an influx of Na+

graded potential

occurs in the dendrites or cell body

action potential

begin as graded potentials (small local depolarization) leading to widespread depolarization of the cell

both

Na+ flows through voltage channels when the membrane potential reaches threshold

graded potential

change in depolarization only moves the membrane from -70mV to -65 mV

action potential

must reach a certain threshold to propagate, termed the all or nothing principle

both

repolarization caused by an efflux of K+

graded potential

membrane potential decreases with amplitude with distance

action potential

leads to release of a neurotransmitter from the axon terminal

both

voltage K+ channels open once voltage Na+ channels close

graded potential

summate spatially or temporally

both

hyperpolarization caused by excessive K+ leaving the cell

graded potential

no refractory period

both

resting state stored by Na/K ATPase (sodium potassium pumps)

graded potential

ligand gated channels