"Stimulus 1 Amplitude" to 0 and "Sweep Duration" to 20 ms. Now slowly raise the "K+ equilibrium potential" to more and more positive values. As the K+ equilibrium potential is raised, you will observe the following sequence of events. The membrane potential depolarizes. Spontaneous action potentials are generated. The frequency of the action potentials increases. The amplitude of the action potentials diminishes. The action potentials die out as the membrane potential continues to depolarize. The same sequence of events occurs during spreading depression episodes in the cortex. During spreading depression, extracellular K+ concentration increases from a normal level of 3 mM to 50 mM or more. Spreading depression is thought to underlie the symptoms of migraine headache in the visual cortex, with the spontaneously generated action potentials resulting in visual auras that sometimes accompany migraines, and the loss of action potential generation resulting in a visual scotoma. Can you explain why this sequence of events occurs when the K+ equilibrium potential is raised? 9. Multiple Sclerosis. The symptoms of multiple sclerosis are caused by conduction failure due to the demyelination of CNS axons. The symptoms of multiple sclerosis are alleviated by lowering a patient's core body temperature while symptoms are exacerbated by an exercise-induced rise in body temperature. MetaNeuron can be used to investigate the effect of temperature on action potential generation. Starting with the default parameter values, adjust the stimulus amplitude so that it is just below threshold for initiating an action potential. Now vary the temperature. How much does the temperature have to be lowered to evoke an action potential? Starting again from the default parameter values, adjust the stimulus amplitude so that it is just above threshold for initiating an action potential. How much does the temperature have to be raised to block initiation of the action potential? In a patient with conduction block, lowering their core body temperature will restore conduction by lowering the threshold for action potential generation. Why does lowering the temperature reduce the threshold for action potential generation?
"Stimulus 1 Amplitude" to 0 and "Sweep Duration" to 20 ms. Now slowly raise the "K+ equilibrium potential" to more and more positive values. As the K+ equilibrium potential is raised, you will observe the following sequence of events. The membrane potential depolarizes. Spontaneous action potentials are generated. The frequency of the action potentials increases. The amplitude of the action potentials diminishes. The action potentials die out as the membrane potential continues to depolarize. The same sequence of events occurs during spreading depression episodes in the cortex. During spreading depression, extracellular K+ concentration increases from a normal level of 3 mM to 50 mM or more. Spreading depression is thought to underlie the symptoms of migraine headache in the visual cortex, with the spontaneously generated action potentials resulting in visual auras that sometimes accompany migraines, and the loss of action potential generation resulting in a visual scotoma. Can you explain why this sequence of events occurs when the K+ equilibrium potential is raised? 9. Multiple Sclerosis. The symptoms of multiple sclerosis are caused by conduction failure due to the demyelination of CNS axons. The symptoms of multiple sclerosis are alleviated by lowering a patient's core body temperature while symptoms are exacerbated by an exercise-induced rise in body temperature. MetaNeuron can be used to investigate the effect of temperature on action potential generation. Starting with the default parameter values, adjust the stimulus amplitude so that it is just below threshold for initiating an action potential. Now vary the temperature. How much does the temperature have to be lowered to evoke an action potential? Starting again from the default parameter values, adjust the stimulus amplitude so that it is just above threshold for initiating an action potential. How much does the temperature have to be raised to block initiation of the action potential? In a patient with conduction block, lowering their core body temperature will restore conduction by lowering the threshold for action potential generation. Why does lowering the temperature reduce the threshold for action potential generation?
Human Anatomy & Physiology (11th Edition)
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Author:Elaine N. Marieb, Katja N. Hoehn
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Chapter1: The Human Body: An Orientation
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Transcribed Image Text:"Stimulus 1 Amplitude" to 0 and "Sweep Duration" to 20 ms. Now slowly raise the
"K+ equilibrium potential" to more and more positive values. As the K+ equilibrium
potential is raised, you will observe the following sequence of events.
The membrane potential depolarizes.
Spontaneous action potentials are generated.
The frequency of the action potentials increases.
The amplitude of the action potentials diminishes.
The action potentials die out as the membrane potential continues to depolarize.
The same sequence of events occurs during spreading depression episodes in
the cortex. During spreading depression, extracellular K+concentration increases
from a normal level of 3 mM to 50 mM or more. Spreading depression is thought
to underlie the symptoms of migraine headache in the visual cortex, with the
spontaneously generated action potentials resulting in visual auras that
sometimes accompany migraines, and the loss of action potential generation
resulting in a visual scotoma.
Can you explain why this sequence of events occurs when the K+ equilibrium
potential is raised?
9. Multiple Sclerosis. The symptoms of multiple sclerosis are caused by
conduction failure due to the demyelination of CNS axons. The symptoms of
multiple sclerosis are alleviated by lowering a patient's core body temperature
while symptoms are exacerbated by an exercise-induced rise in body
temperature. MetaNeuron can be used to investigate the effect of temperature on
action potential generation. Starting with the default parameter values, adjust the
stimulus amplitude so that it is just below threshold for initiating an action
potential. Now vary the temperature. How much does the temperature have to be
lowered to evoke an action potential? Starting again from the default parameter
values, adjust the stimulus amplitude so that it is just above threshold for
initiating an action potential. How much does the temperature have to be raised.
to block initiation of the action potential? In a patient with conduction block,
lowering their core body temperature will restore conduction by lowering the
threshold for action potential generation.
Why does lowering the temperature reduce the threshold for action potential
generation?
Transcribed Image Text:7. Anodal Break excitation. Starting with the default parameter values, set
"Sweep Duration" to 10 msec. Now decrease the "Stimulus 1 Amplitude” until it
reaches-225 μA. An action potential is evoked by the hyperpolarizing stimulus!
This phenomenon is called anode break excitation. Can you explain why a
hyperpolarizing stimulus evokes an action potential?
8. Spreading Depression. Starting with the default parameter values, set
"Stimulus 1 Amplitude" to 0 and "Sweep Duration" to 20 ms. Now slowly raise the
"K+ equilibrium potential" to more and more positive values. As the K+ equilibrium
potential is raised, you will observe the following sequence of events.
The membrane potential depolarizes.
Spontaneous action potentials are generated.
The frequency of the action potentials increases.
The amplitude of the action potentials diminishes.
The action potentials die out as the membrane potential continues to depolarize.
The same sequence of events occurs during spreading depression episodes in
the cortex. During spreading depression, extracellular K+ concentration increases
from a normal level of 3 mM to 50 mM or more. Spreading depression is thought
to underlie the symptoms of migraine headache in the visual cortex, with the
spontaneously generated action potentials resulting in visual auras that
sometimes accompany migraines, and the loss of action potential generation
resulting in a visual scotoma.
Can you explain why this sequence of events occurs when the K+ equilibrium
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