PATHOLOGY MCQ
NERVOUS SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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is the minimum hyperpolarization needed to prevent the occurrence of action potentials.
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is the peak amount of depolarization seen in an action potential.
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is the lowest frequency of action potentials a neuron can produce.
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is the point of separation from a living from a dead neuron
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is the minimum depolarization needed to operate the voltage-gated sodium and potassium channels
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Detailed explanation-1: -The “threshold” potential of a membrane: is the minimum depolarization needed to operate the voltage-gated sodium and potassium channels. After the depolarization phase of an action potential, the resting potential is restored by: the opening of voltage-gated potassium channels and the closing of sodium channels.
Detailed explanation-2: -The basis is that at a certain level of depolarization, when the currents are equal and opposite in an unstable manner, any further entry of positive charge generates an action potential. This specific value of depolarization (in mV) is otherwise known as the threshold potential.
Detailed explanation-3: -The threshold is the value of the membrane potential which, if reached, leads to the all-or-nothing initiation of an action potential. The initial or rising phase of the action potential is called the depolarizing phase or the upstroke.
Detailed explanation-4: -When the depolarization reaches about-55 mV a neuron will fire an action potential. This is the threshold.