Passage of an Action Potential

Question 1

How does an action potential travel along an axon?

Answer 1

As a travelling wave of depolarisation, where each region of the axon membrane stimulates the next to depolarise

Question 2

Does the size of the action potential change as it moves along the axon?

Answer 2

No, the size of the action potential remains the same from one end of the axon to the other

Question 3

What happens in a region of the axon after it has been depolarised?

Answer 3

It undergoes repolarisation, returning to its resting potential

Question 4

Does anything physically move aong the axon during an action potential?

Answer 4

No, instead, the depolarisation of one region stimulates the next region to depolarise

Question 5

What is the state of ion distribution at resting potential?

Answer 5

High sodium ion concentration outside the axon, high potassium ion concentration inside.
The outside is more positive than the inside, making the membrane polarised

Question 6

What happens when a stimulus is detected by a neurone?

Answer 6

Sodium voltage - gated channels open, causing a sudden influx of sodium ions into the axon. This reverses the charge across the membrane, leading to depolarisation

Question 7

How does the action potential propagate along the axon?

Answer 7

The influx of sodium ions trigger soidu voltage gated channels further along the axon to open, spreading depolarisation. Meanwhile, potassium channels open, allowing potassium ions to leave, repolarising the previous region

Question 7

What happens t the region behind the action potential?

Answer 7

Sodium channels close, potassium channels open, and potassium ions diffuse out, restoring the original charge distribution

Question 8

How does the axon return to resting potential after an action potential has passed?

Answer 8

Sodium - potassium pumps actively transport sodium ions out and potassium ions in, restoring the resting potential and making the neuron ready for a new stimulus