PHYSIOLOGY
SYNAPTIC PHYSIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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This is the largest charge achieved during an action potential
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This is the threshold required to complete an action potential
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This is the resting charge of a neuron
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This is the charge when all the sodium is inside the cell
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Detailed explanation-1: -When the depolarization reaches about-55 mV a neuron will fire an action potential. This is the threshold. If the neuron does not reach this critical threshold level, then no action potential will fire.
Detailed explanation-2: -The threshold potential for most excitable cells is about 15 mV less negative than the resting membrane potential. In a nerve, if the membrane potential decreases from-70 mV to-55 mV the cell fires an action potential which propagates along the axon.
Detailed explanation-3: -To begin an action potential, the membrane potential must change from the resting potential of approximately-70mV to the threshold voltage of-55mV. Once the cell reaches threshold, voltage-gated sodium channels open and being the predictable membrane potential changes describe above as an action potential.
Detailed explanation-4: -We note that the threshold is determined by the value of conductances relative to the leak conductance rather than by their absolute value.
Detailed explanation-5: -Threshold is the minimum current required for the cell membrane to generate an action potential. True. For an action potential to happen, a local potential must rise to a critical voltage called the threshold (typically about-55 mV)-the minimum needed to open voltage-gated channels.