MYTUTOR SUBJECT ANSWERS

750 views

Explain how a nerve impulse passes along a non-myelinated neuron.

Generation of a Resting Potential

▪       The sodium-potassium pump (Na+/K+ pump) maintains the electrochemical gradient of the resting potential (-70 mV)

▪       It is a membrane protein that uses active transport to exchange Na+ and K+ ions across the membrane

▪       It expels 3 Na+ ions for every 2 K+ ions admitted (in addition, some of the K+ ions will leak back out of the cell)

▪       This makes the inside of the membrane relatively negative when compared to the outside (-70 mV = resting potential)

 

 

Sodium (Na) is found in greater concentrations outside of the cell while potassium  (K) is found in greater concentrations inside the cell. Sodium-potassium pumps exist in the plasma membrane to maintain the concentration gradients and the membrane potential. 

Nerve impulses have a domino effect. An action potential in one part of the neuron causes another action potential in the adjacent part and so on. This is due to the diffusion of sodium ions between the region of the action potential and the resting potential. It is the movement of sodium and potassium that reduce the resting potential.

If the resting potential rises above the threshold level, voltage gated channels open. Voltage gated sodium channels open very fast so that sodium can diffuse into the cell down its concentration gradient. This reduces the membrane potential and results in more sodium channels opening. Sodium ions are positively charged and so the inside of the cell develops a net positive charge compared to the outside of the cell. This results in depolarization as the potential across the membrane is reversed.

A short while after this, voltage gated potassium channels open and potassium ions flow out of the cell down the concentration gradient. Since potassium ions are positively charged, their diffusion out of the cell causes a net negative charge to develop again inside the cell compared to the outside. The potential across the membrane is restored. This is called repolarization

Finally, the concentration gradients of both ions are restored by the sodium-potassium pump. Sodium is pumped out of the cell while potassium is pumped in. The resting potential is restored and the neuron is ready to conduct another nerve impulse. 

Zana Katarina L. IB Biology tutor, IB Maths tutor, IB Psychology tutor

2 years ago

Answered by Zana Katarina, an IB Biology tutor with MyTutor


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

23 SUBJECT SPECIALISTS

£20 /hr

Wisdom O.

Degree: Medicine, MBBS iBsc (Bachelors) - University College London University

Subjects offered: Biology, Maths+ 5 more

Biology
Maths
German
Chemistry
-Personal Statements-
-Oxbridge Preparation-
-Medical School Preparation-

“ABOUT ME   I'm a first year medical student at University College London. I really enjoy sciences and languages and I work hard to convey my passion and interest in these subjects to those I tutor.  I am very friendly and tutoring my ...”

£20 /hr

Zoe G.

Degree: Chemistry (Bachelors) - Edinburgh University

Subjects offered: Biology, French+ 2 more

Biology
French
Chemistry
-Personal Statements-

“I am a student at Edinburgh University studying Chemistry. I aim to make the learning process of Chemistry, Biology and French much clearer and more enjoyable! I genuinely love studying these subjects and I am looking forwards to pass...”

MyTutor guarantee

£22 /hr

Oliver W.

Degree: Natural Sciences (Bachelors) - Cambridge University

Subjects offered: Biology, Maths+ 4 more

Biology
Maths
Extended Project Qualification
Economics
Chemistry
-Personal Statements-

“I am third year student at the University of Cambridge studying Natural Sciences. I specialise in Neurobiology. However, I have a lot of experience in othersciences and maths, at GCSE and IB level. I studied for 5 years at Sevenoaks Sc...”

About the author

£20 /hr

Zana Katarina L.

Degree: Psychology (Bachelors) - Durham University

Subjects offered: Biology, Psychology+ 1 more

Biology
Psychology
Maths

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

MyTutor guarantee

You may also like...

Posts by Zana Katarina

Describe one example of transient polymorphism.

Discuss the relative importance of genetic and cultural evolution in the recent evolution of humans.

Analyze the changes in concentration of atmospheric carbon dioxide using historical records.

Behaviour can be innate because it is genetically based and can be inherited.

Other IB Biology questions

What are the structural and functional differences between arteries and veins?

Discuss the incompleteness of the fossil record and the resulting uncertainties about human evolution.

How can an impulse be passed along a membrane?

What is the Krebs/TCA/Citric Acid cycle?

View IB Biology tutors

Cookies:

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

mtw:mercury1:status:ok