What is meant by the resting potential of an axon?

The resting potential is the potential difference maintained across the axon membrane when no impulse is being transmitted, with the inside negative relative to the outside.

State the all-or-nothing law.

An action potential is either produced at its full size or not produced at all, and its size does not depend on how far the stimulus exceeds the threshold.

What happens to the membrane potential during depolarisation?

The potential difference across the membrane is reversed, so the inside of the axon briefly becomes positive relative to the outside.

CCEA A-Level Biology 1010

Biological Molecules

Topic overview Water as a solvent Inorganic ions and their roles Monosaccharides and the glycosidic bond Disaccharides and polysaccharides Lipids, triglycerides and phospholipids Amino acids and protein structure Protein shape, conjugated proteins and prions Nucleic acids: nucleotides, DNA and RNA DNA replication and the Meselson–Stahl experiment Biochemical tests and paper chromatography

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Co-Ordination and Control

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Co-Ordination and Control

Resting potential, threshold and the action potential

3 things to know
Unit A2 1

Overview

Resting potential of an axon, typical value for the resting potential of a mammalian axon and threshold stimulus.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What does it mean to say that a resting axon membrane is polarised?

Key term

State a typical value for the resting potential of a mammalian axon.

Key term

Define a threshold stimulus.

Questions from this subtopic

Each one with the model answer underneath.

1
What is meant by the resting potential of an axon?
Model answer
The resting potential is the potential difference maintained across the axon membrane when no impulse is being transmitted, with the inside negative relative to the outside.
2
What does it mean to say that a resting axon membrane is polarised?
Model answer
Opposite charges are separated across the membrane, so there is a steady potential difference between the inside and the outside.
3
State a typical value for the resting potential of a mammalian axon.
Model answer
A typical resting potential is about −70 mV.
4
Define a threshold stimulus.
Model answer
A threshold stimulus is the minimum intensity of stimulus that will trigger an action potential in a neurone.
5
State the all-or-nothing law.
Model answer
An action potential is either produced at its full size or not produced at all, and its size does not depend on how far the stimulus exceeds the threshold.
6
What happens to the membrane potential during depolarisation?
Model answer
The potential difference across the membrane is reversed, so the inside of the axon briefly becomes positive relative to the outside.

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