What Is Absolute Magnitude?

Absolute refractory period: During the initial period after the excitement, no matter how strong the stimulus is applied, the cells cannot be excited again. This period of time is called the absolute refractory period, and the excitability decreases to 0. Corresponds to the peak potential period of the action potential.

Absolute refractory period

Because Na channels are all open or inactive, they cannot be generated by Na inflow.

The absolute refractory period is approximately equivalent to the time when the spike potential occurs, so the spike potential does not overlap, and the maximum frequency of the spike potential is also limited by the absolute refractory period. The absolute refractory period determines the minimum interval between successive excitements.

Relative refractory period: After the absolute refractory period, the Na ion channel is partially opened, Na ion flows in, and the excitability of the cell gradually recovers. Excitation can occur after stimulation, but the stimulation must be greater than the original threshold intensity. This period is called Relative refractory period.

Stimulus relative refractory period

Extraordinary period. A-fibers in mammals appear between 10-20 milliseconds after stimulation and then turn into a subnormal phase. The abnormal period is generally consistent with the time required for the negative post-action potential of the action potential. The B fiber has no abnormal period, and the post-node fiber (C fiber) has an abnormal period within 50-100 milliseconds after stimulation.

Low regularity. The one-time excitability that appears after the stimulus excites it is lower than the normal value, and the low normal period is a relatively refractory period. ^[1]