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Flip to reveal answersWhat is the resting potential of a neuron?
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All 13 Flashcards — Resting potential
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Question
What is the resting potential of a neuron?
Answer
The voltage across the membrane of a neuron that is **not** conducting an impulse — the inside is about **−70 mV** (negative) relative to the outside.
Question
Roughly what value is the resting potential?
Answer
About **−70 mV** (the inside is negative relative to the outside).
Question
Is the inside of a resting neuron positive or negative?
Answer
**Negative** — about −70 mV compared with the outside.
Question
What is the sodium-potassium pump?
Answer
A membrane protein that uses **ATP** to move **Na⁺ out** of the neuron and **K⁺ in**, against their concentration gradients.
Question
How many of each ion does the pump move per cycle?
Answer
**3 sodium ions (Na⁺) out** and **2 potassium ions (K⁺) in**.
Question
Why does the inside of the neuron become negative?
Answer
The pump moves **3 positive ions out for every 2 in**, so more positive charge leaves than enters; **K⁺ leaking back out** makes it more negative still.
Question
Why does the sodium-potassium pump need ATP?
Answer
It moves ions **against their concentration gradients** — this is **active transport**, which requires energy from ATP.
Question
Where does the ATP for the pump come from?
Answer
From **cell respiration** (in the neuron's mitochondria).
Question
What is active transport?
Answer
Movement of a substance across a membrane **against** its concentration gradient, requiring energy from **ATP**.
Question
What happens to the resting potential if a neuron cannot respire?
Answer
It is **lost** — no respiration → no ATP → the pump stops → the ion gradients run down.
Question
What does potassium do after the pump builds it up inside?
Answer
Some **K⁺ leaks back out** down its concentration gradient, making the inside **more negative**.
Question
In a resting axon, where is sodium more concentrated?
Answer
**Outside** the axon (the pump keeps Na⁺ high outside and low inside).
Question
In a resting axon, where is potassium more concentrated?
Answer
**Inside** the axon (the pump keeps K⁺ high inside and low outside).
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Neural signalling
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