Transmission of Action Potentials (4.1.2)

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How is a local circuit created?
Na+ channels open, allowing Na+ ions to diffuse in. Localised increase in Na+ conc. in neurone. Na+ ions diffuse along axon/dendron, away from high concentration. Sodium gate will open due to movement of Na+ ions- action potential moves along neurone
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How does depolarisation use positive feedback?
The response is to increase the original change. Once some Na+ ions move in, it causes even more to move in. Allowing the wave of depolarisation to pass all the way along the neurone.
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How does the brain distinguish the difference between different stimulus intensities?
Different frequencies of action potentials are perceived. A stronger stimulus results in more frequent action potentials to the brain/CNS. A stronger stimulus is also likely to stimulate more neurones.
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Describe the transmission of a nerve impulse across a neurone.
Higher conc. of Na+ outside & K+ inside. Stimulus- Na+ channels open. Ions diffuse in- depolarisation. Localised electrical circuits alter charge difference across membrane- opens volt.-gated Na+ channels. A.P moves along neurone, recovery just behin
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How does the brain know the nature of the stimulus?
It perceives it according to which sensory neurone delivers the information.
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Card 2

Front

How does depolarisation use positive feedback?

Back

The response is to increase the original change. Once some Na+ ions move in, it causes even more to move in. Allowing the wave of depolarisation to pass all the way along the neurone.

Card 3

Front

How does the brain distinguish the difference between different stimulus intensities?

Back

Preview of the front of card 3

Card 4

Front

Describe the transmission of a nerve impulse across a neurone.

Back

Preview of the front of card 4

Card 5

Front

How does the brain know the nature of the stimulus?

Back

Preview of the front of card 5

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