How does the sodium-potassium pump contribute to establishing the resting potential?

The sodium-potassium pump actively transports 3 Na⁺ ions out and 2 K⁺ ions into the axon using ATP, creating a net loss of positive charge from inside the cell.

Why does the differential permeability of the axon membrane to K⁺ and Na⁺ contribute to the resting potential?

At rest, the membrane is more permeable to K⁺ than Na⁺, so K⁺ diffuses out through potassium ion channels, contributing to the negative resting potential.

What must occur for an action potential to be generated?

A stimulus must cause depolarisation to reach the threshold potential (approximately −55 mV).

What initiates the opening of voltage-gated sodium channels during depolarisation?

A stimulus causes the membrane to reach threshold potential.

What happens to voltage-gated Na⁺ channels when threshold is reached?

Voltage-gated Na⁺ channels open.

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Neuronal Communication

Resting potential and the action potential

3 things to know
Components 01 and 03

Overview

The sodium-potassium pump and membrane permeability at rest, depolarisation, repolarisation and hyperpolarisation, the refractory period, and the all-or-nothing rule.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

Outline an action potential.

Key term

Why is the refractory period important?

Key term

What is the resting potential of a neurone and what does it indicate about charge distribution?

Questions from this subtopic

Each one with the model answer underneath.

1
What is the resting potential of a neurone and what does it indicate about charge distribution?
Model answer
The resting potential is approximately −70 mV, with the inside of the axon negatively charged relative to the outside.
2
How does the sodium-potassium pump contribute to establishing the resting potential?
Model answer
The sodium-potassium pump actively transports 3 Na⁺ ions out and 2 K⁺ ions into the axon using ATP, creating a net loss of positive charge from inside the cell.
3
Why does the differential permeability of the axon membrane to K⁺ and Na⁺ contribute to the resting potential?
Model answer
At rest, the membrane is more permeable to K⁺ than Na⁺, so K⁺ diffuses out through potassium ion channels, contributing to the negative resting potential.
4
What must occur for an action potential to be generated?
Model answer
A stimulus must cause depolarisation to reach the threshold potential (approximately −55 mV).
5
What initiates the opening of voltage-gated sodium channels during depolarisation?
Model answer
A stimulus causes the membrane to reach threshold potential.
6
What happens to voltage-gated Na⁺ channels when threshold is reached?
Model answer
Voltage-gated Na⁺ channels open.

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