What is the refractory period of a nerve action potential?

The refractory period is composed of two parts. The first part is the absolute refractory period in which another action potential cannot be stimulated in the nerve. In the relative refractory period that follows an action potential can occur but a greater depolarising stimulus than usual is required. The reason for the refractory period is due to the time and voltage characteristics of the Na+ and K+ channels that govern the membrane potential. The absolute refractory period is due to the inactivation of sodium channels where sodium ions cannot enter the channel to depolarise the membrane and occurs after the initiation of action potential spike. During the relative refractory period, sodium channels return to a state where they can conduct sodium but the potassium channels are delayed in closing leading to hyperpolarisation. Therefore more depolarising stimulus is necessary in the relative refractory period. 

KK
Answered by Karthik K. Biology tutor

10985 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

What are the four chambers of the heart and what do they do?


Humans and grasshoppers have very similar percentages of each base in their DNA but they are very different organisms. Use your knowledge of DNA structure and function to explain how this is possible (2 Marks)


Maltose is hydrolysed by the enzyme maltase. Explain why maltase catalyses only this reaction (3 marks)


Why does a plant not take in all of the light energy that reaches their leaves?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning