EMBRYOLOGY
NERVOUS SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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What behavior is observed if the voltage across a neuronal membrane is set to-20 mV?
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The sodium channel opens, and Na+ ions flow in.
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The voltage-gated sodium and potassium channels both remain closed
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The sodium channel opens, and Na+ ions flow out.
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The potassium channel opens, and K+ ions flow in.
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Explanation:
Detailed explanation-1: -As the membrane potential reaches +30 mV, other voltage-gated channels are opening in the membrane. These channels are specific for the potassium ion. A concentration gradient acts on K+, as well.
Detailed explanation-2: -A voltage change that reaches threshold will cause voltage-gated sodium channels to open in the axonal membrane. The influx of sodium causes the rising phase of the action potential, but the ion flow also depolarizes nearby axon regions. As the depolarization reaches threshold, the action potential moves down the axon.
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