MYTUTOR SUBJECT ANSWERS

414 views

Describe the changes at the cell membrane of a neuron during an action potential.

At rest the membrane potential is -70mV.

This is due to the  Na+/K+ pump, which actively transports 3 Na+ ions out of the cell for every 2 K+ ions in.

Therefore there is a net negative charge inside the cell.

Four stages:

Depolarization; Repolarization;Hyperpolarization; Afterhyperpolarization.

Depolarization - triggered by another neuron. The membrane becomes more leaky to Na+, so Na+ diffuses into the cell down an electrochemical gradient. This makes the potential difference across the membrane become more positive. Eventually a Threshold potential of -55mV is reached, which activates the voltage-gated Na+ channels. These open and allow a lot of Na+ to enter the neuron.

Repolarization - at +30mV the voltage-gated Na+ channels close and the voltage-gated K+ channels open. K+ diffuses out of the cell through the open channels, causing the membrane potential to become more negative again.

Hyperpolarization - or the 'overshoot' is when the membrane potential becomes more negative than the resting potential, due to prolonged K+ efflux.

Afterhyperpolarization - restoring the resting membrane potential. At this point the membrane potential is too negative AND the ions (Na+ and K+) are on the wrong side of the membrane. The Na+/K+ pump works to restore the ions to their correct sides and a new action potential cannot be generated.

Alex N. GCSE Biology tutor, A Level Biology tutor, GCSE Chemistry tut...

1 year ago

Answered by Alex, an A Level Biology tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

167 SUBJECT SPECIALISTS

£20 /hr

Bethany R.

Degree: Biology (Bachelors) - Bristol University

Subjects offered:Biology, Spanish

Biology
Spanish

“I help students achieve the best results they can, simple as that! My tutoring style is flexible and I'm happy to try any approach that helps you.”

£36 /hr

Hannah S.

Degree: Medicinal Chemistry and Pharmacology (Masters) - Liverpool University

Subjects offered:Biology, English Language+ 3 more

Biology
English Language
Chemistry
-Personal Statements-

“I'm currently studying medicinal chemistry and pharmacology at the University of Liverpool as part of an 'integrated masters' course designed to fast track students interested in a chemistry as a profession or continuing study to a PhD...”

£20 /hr

Andrea D.

Degree: Neuroscience (Bachelors) - Manchester University

Subjects offered:Biology, Spanish+ 1 more

Biology
Spanish
-Personal Statements-

“Biology enthusiast studying neuroscience at The University of Manchester, ready to try my best to help you understand and love biology!”

About the author

£20 /hr

Alex N.

Degree: Biomedical Science (Bachelors) - Oxford, St Anne's College University

Subjects offered:Biology, Science+ 4 more

Biology
Science
Maths
Chemistry
.BMAT (BioMedical Admissions)
-Personal Statements-

“Top tutor from the renowned Russell university group, ready to help you improve your grades.”

MyTutor guarantee

You may also like...

Posts by Alex

Describe the changes at the cell membrane of a neuron during an action potential.

Dipen and Nisha are planning their wedding reception. Nisha says, “I want to invite 70 guests.” Dipen says, “If we invite one-fifth fewer guests, we will save more than £500” Is Dipen correct? (Taken from Nov 2014 AQA Unit 2)

Other A Level Biology questions

How do fish carry out gas exchange efficiently?

Explain the concepts of primary, secondary, tertiary and quaternary

How does eutrophication work?

What are the different phases of the cell cycle?

View A Level Biology tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok