What is the Difference Between Absolute and Relative Refractory Period?

The refractory period is a time during which a cell is incapable of repeating an action, specifically in the context of action potentials in neurons. There are two types of refractory periods: the absolute refractory period and the relative refractory period.

Absolute Refractory Period: This refers to the time span in which the sodium-gated ion channels are completely inactive. During this period, a new spike cannot be triggered by any stimuli. The absolute refractory period corresponds to depolarization and repolarization.
Relative Refractory Period: This is the interval of time during which a second action potential can be initiated, but it will require a greater stimulus than before. During the relative refractory period, the inward sodium currents are shunted by opposing potassium conductances, allowing new spikes to be triggered by stronger stimuli. The relative refractory period corresponds to hyperpolarization.

In summary, the key difference between the absolute and relative refractory periods lies in their ability to respond to stimuli:

During the absolute refractory period, no stimulus can trigger a second action potential.
During the relative refractory period, a stronger stimulus than usual is required to produce the action potential.

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What is the Difference Between Absolute and Relative Refractory Period?

Comparative Table: Absolute vs Relative Refractory Period

The difference between absolute and relative refractory periods lies in their respective features and characteristics. Here is a table that provides a comparison between the two:

Feature	Absolute Refractory Period	Relative Refractory Period
Definition	The absolute refractory period refers to the time span in which sodium-gated ion channels are completely inactive.	The relative refractory period is the phenomenon in which the sodium-gated channels transition from being fully inactive to becoming partially active.
Stimulus Requirement	During the absolute refractory period, a stimulus will not produce a second action potential, regardless of its intensity.	During the relative refractory period, a stimulus must be stronger than the usual to produce an action potential.
Occurrence	The absolute refractory period occurs first, following the firing of a nerve fiber.	The relative refractory period occurs after the absolute refractory period.
Significance	The absolute refractory period ensures that an excitable membrane is ready for a second stimulus and prevents multiple action potentials from firing simultaneously.	The relative refractory period allows the excitable membrane to recover and prepare for the next action potential.

In summary, the absolute refractory period is a time when another action potential is not possible due to the complete inactivity of sodium-gated ion channels, while the relative refractory period allows for the partial activity of these channels, requiring a stronger stimulus to produce an action potential.

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.