PATHOLOGY MCQ
NERVOUS SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The sodium-potassium pump shuttles ions across the membrane.
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The membrane depolarizes above a certain threshold potential.
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Voltage-gated potassium channels open, and K+ ions diffuse out of the neuron.
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There is an undershoot of the resting potential.
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Detailed explanation-1: -In neurons, the rapid rise in potential, depolarization, is an all-or-nothing event that is initiated by the opening of sodium ion channels within the plasma membrane. The subsequent return to resting potential, repolarization, is mediated by the opening of potassium ion channels.
Detailed explanation-2: -Action potentials are caused when different ions cross the neuron membrane. A stimulus first causes sodium channels to open. Because there are many more sodium ions on the outside, and the inside of the neuron is negative relative to the outside, sodium ions rush into the neuron.
Detailed explanation-3: -Synaptic inputs to a neuron cause the membrane to depolarize or hyperpolarize; that is, they cause the membrane potential to rise or fall. Action potentials are triggered when enough depolarization accumulates to bring the membrane potential up to threshold.
Detailed explanation-4: -On depolarization of the membrane to the less negative threshold voltage, the Na+ channels open, resulting in an influx of positively charged ions (the inward Na+ current) and rapid reversal of membrane polarity.