Can you explain the main events that happen during an action potential?

What is an action potential? When a stimulus of sufficient size is detected, it causes a temporary reversal of charges either side of the axon membrane. It also causes the channels in the axon membrane to change shape, (to open/close) A nerve impulse in an unmyelinated neurone can be split in to 5 main events STIMULUS- causes some Na+ voltage gated channels to open, causing Na+ to diffuse down an electrochemical gradient into the neurone. DEPOLARISATION - The inner membrane becomes more positive as Na+ diffuses in. When the threshold value is reached, (approx. -50mV), many more Na+ channels open and there is an influx of Na+. REPOLARISATION- when the inner membrane has an action potential of +40mV, this causes voltage gates Na+ channels to close and voltage gates K+ channels to open. HYPERPOLARISATION- K+ effluxes out of the cell, however there is an overshoot of K+ ions since K+ channels are slow to close. Once the K+ channels eventually close, the ionic concentrations inside and outside of the cell can be reset to the resting membrane potential RESTING POTENTIAL- both K+ and Na+ channels are closed. A Na+/K+ pump uses ATP to reestablish the resting potential. ( will draw the diagram of an action potential)

DN
Answered by Dominique N. Biology tutor

2227 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

Explain the Cardiac Cycle


If you're measuring an environment using a quadrat or another sampling instrument - why can't you just do it where you see the most biodiversity?


Describe and explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria from a suspension of animal cells.


A fault opens in a forest and separates a population of lizards in half. In 100 years the fault closes and the lizards can interact again. Explain why the lizards are no longer able to breed.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences