What is the Difference Between Graded Potential and Action Potential?

🆚 Go to Comparative Table 🆚

The main differences between graded potentials and action potentials are:

Propagation: Graded potentials are not fully propagated along the membrane, and their amplitude decreases as they spread due to leakage of sodium ions through the resistance and capacitance of the membrane. In contrast, action potentials are considered an "all-or-nothing" event, and once the threshold potential is reached, the neuron always completely depolarizes, regardless of the stimulus strength.
Depolarization or Hyperpolarization: Depending on the stimulus, graded potentials can be either depolarizing or hyperpolarizing. Action potentials, however, always lead to depolarization of the membrane and reversal of the membrane potential.
Amplitude: The amplitude of graded potentials is proportional to the strength of the stimulus. In contrast, the amplitude of action potentials is all-or-none, and the strength of the stimulus is coded in the frequency of action potentials generated.
Activation: Graded potentials can be summed over time (temporal summation) and across space (spatial summation). Action potentials, due to their all-or-none nature and the presence of refractory periods, cannot be summed.
Refractory Period: Graded potentials do not have a refractory period. Action potentials, on the other hand, have both absolute and relative refractory periods.
Ions Involved: Graded potentials can involve various ions, such as Na+, K+, or Cl−. Action potentials in neurons, specifically, involve Na+ and K+ ions.
Location: Graded potentials mainly occur in dendrites and cell bodies. Action potentials are a result of graded potentials and are triggered when the membrane potential reaches a specific threshold.

On this page

What is the Difference Between Graded Potential and Action Potential?

Comparative Table: Graded Potential vs Action Potential

Here is a table comparing the differences between graded potentials and action potentials:

Feature	Graded Potentials	Action Potentials
Amplitude	Generally small (a few mV to tens of mV)	Large amplitude of ~100 mV
Duration	May be a few milliseconds to seconds	Relatively short, around 3-5 ms
Ions Involved	Usually Na+, K+, or Cl−	Na+ and K+ for neuronal action potentials
Refractory Period	No refractory period	Absolute and relative refractory periods are important aspects
Summation	Can be summed over time (temporal summation) and across space (spatial summation)	Summation is not possible due to the all-or-none nature and the presence of refractory periods
Physiology	Can be depolarizing or hyperpolarizing depending on the stimulus	Always leads to depolarization of membrane and reversal of the membrane potential
Amplitude	Proportional to the strength of the stimulus	All-or-none; strength of the stimulus is coded in the frequency of all-or-none action potentials generated
Propagation	Passive spread (electrotonic spread) to neighboring membrane regions	Characterized by regeneration of a propagating action potential
Amplitude Decrement	Amplitude diminishes as graded potentials travel away from the initial site	Amplitude does not diminish as action potentials propagate along neuronal projections
Signal Type	Analog signal	Binary all-or-nothing event
Distance	Short-distance signals	Long-distance signals

Graded potentials are small changes in the membrane potential that can reinforce or negate each other, while action potentials are large, all-or-none changes in the membrane potential that serve as long-distance signals.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.