properties of excitable cell

Rheobase is the lowest current that will initiate an action potential. the chronaxie is the maximum stimulus duration when the current is 2X reheobase. Rheobase and chronaxie define the shape of the strength-duration relationship. A slowly inceasing depolarizing current may not initiate an action potential even though it may rise to an intensity much greater than threshold level. A maintained depolarization causes the threshold to rise towards 0 mV. This called as accomadation.

It is not possible to elicit a second action potential after brief period of first action potential. This period is called as absolute refractory period. in this period all Na channels again can be aplicable for activation, this period is called as relative refractory period.