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Jan%2021%20questions - Why does an action potential...

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Question: Acetylcholine-gated cation channels allow Na + , K + and Ca 2+ to pass through. Why is it mostly Na + that flows in? Answer: K + is near equilibrium, Na + is not. Ca 2+ also flows in but its concentration outside is much less than Na + (1mM vs. 140 mM). Question:
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Unformatted text preview: Why does an action potential propagate (move) in only one direction? Why cant it propagate backwards? Answer: Na + channels become refractory after opening and cannot respond to another depolarization for a while....
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