15.3- Passage of an action potential

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Created by: Megan2413
Created on: 27-11-17 18:27

Does the size of an action potential stay the same from one end to the other?

Yes

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What acts as a stimulus for the next region of an axon to become depolarised?

The depolarisation of the previous region

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What happens to the previous region on the axon once it has stimulated the next to depolarise?

The previous region returns to its resting potential (repolarised)

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What can't form where the myelin sheath is present?

An action potential

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What is saltatory conduction?

When the action potential jumps from node to node (of Ranvier)

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Do action potentials travel faster along a myelinated axon or unmyelinated axon?

Myelinated axon

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Describe how an action potential travels along an unmyelinated axon in five steps

1. At resting potential the overall concentration of positive ions is greater on the outside of the membrane hence the axon is polarised 2. A stimulus causes an influx of Na+ ions into the membrane causing an action potential hence depolarisation -->

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of the membrane 3. The influx of Na+ ions opens the voltage-gated sodium channels to open further along the axon depolarising this region. Behind the new region of depolarisation the voltage-gated sodium channels close and potassium ones open, K+ -->

ions leave the axon 4. The action potential is propagated along the axon and the outward movement of K+ ions repolarises the region behind the depolarisation 5. Repolarisation allows Na+ ions to be actively transported out regaining resting potential

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Other cards in this set

Card 2

Front

What acts as a stimulus for the next region of an axon to become depolarised?

Back

The depolarisation of the previous region

Card 3

Front

What happens to the previous region on the axon once it has stimulated the next to depolarise?

Back

Card 4

Front

What can't form where the myelin sheath is present?

Back

Card 5

Front

What is saltatory conduction?

Back

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15.3- Passage of an action potential