PATHOLOGY MCQ
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: -Voltage-gated sodium channels (VGSCs) are the basic ion channels for neuronal excitability, which are crucial for the resting potential and the generation and propagation of action potentials in neurons.
Detailed explanation-2: -Once the sodium channels open, the neuron completely depolarizes to a membrane potential of about +40 mV. Action potentials are considered an “all-or nothing” event, in that, once the threshold potential is reached, the neuron always completely depolarizes.
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