Fill in the blanks: The______is the period of time during which it is impossible to stimulate a neuron to have an action potential, whereas the______ is the period of time during which a larger-than-normal stimulus is required to elicit an action potential.

Video transcript

Hey, everyone. Let's take a look at this question together which of the following describes the absolute refractory period. Is it answer choice? A it happens when the neuron is completely insensitive to a second stimulus. Answer choice B this follows shortly after the firing of a nerve fiber. Answer choice C it contains recovering sodium channels or answer choice D all of the above. Let's work this problem out together to try to figure out which of the following answer choices best describes the absolute refractory period. So in order to solve this question, we have to recall what we have learned about the absolute refractory period to determine which of the following answer choices best describes it. And we can recall that the absolute refractory period refers to the point when the sodium channels are inactivated. And when those sodium channels are inactivated, regardless of the strength or intensity of the stimulus, the neuron cannot be stimulated to generate another action potential. Which means that in this case, during the absolute refractory period, the neuron is insensitive to a second stimulus which helps prevent overlapping action potentials. Which means that answer choice A which states that the absolute refractory period is when the neuron is completely insensitive to a second stimulus is the correct answer. Since the absolute refractory period is the point where these sodium channels are inactivated, which means that regardless of the strength or intensity of the stimulus, the neuron cannot generate another action potential. So it is completely insensitive to a second stimulus. And all other answer choices are incorrect. Since both answer choice B and C are more relevant to the relative refractory period and not the absolute refractory period. So answer choice A is the only correct answer choice. I hope you found this video to be helpful. Thank you and goodbye.