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Is the outer surface of a nerve impulse normally negative and the inner part usually positive?

Answer 1

No. When a neuron is not carrying an impulse, the inside of the axon is negative and the outside is positive.

The cell membrane has a different permeability for different ions.

1. A process called the sodium-potassium pump uses ATP to pump out three #"Na"^+# ions and pump in two #"K"^+# ions.

2. The membrane has ion channels that allow #"K"^+# ions to pass through to the interior of the cell while blocking #"Na"^+# ions.

3. Negatively charged proteins inside the cell cannot pass through the membrane.

In the resting state, these three mechanisms make the inside of the membrane more negative than the outside by about -70 mV.

The diagram below shows a resting neuron. The + signs represent cations and the - signs represent anions.

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Answer 2

Chloe Adams

Yes, that's correct. The outer surface of a nerve impulse is typically negative, while the inner part is usually positive. This is due to the distribution of ions across the nerve cell membrane during the resting state.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.