A series of local potentials causes the membrane potential to move to -80 mV. Pr
ID: 3484139 • Letter: A
Question
A series of local potentials causes the membrane potential to move to -80 mV. Predict the result.
A.
threshold is reached
B.
depolarization occurs
C.
the neuron is hyperpolarized
D.
information of frequency is needed to predict the result
E.
the neuron releases neurotransmitter in response
76.
A neuron is receiving a stimulus which gets stronger and stronger. The result is
A. amplitude of the action potential increases.
B. duration of the action potential increases.
C. frequency of occurrence of action potentials increases.
D. resonance of action potentials increases.
E. height of the action potentials increases.
Explanation / Answer
1. it will be option c. the neuron will become hyperpolarised when approched to a level that is more negative than the normal resting potential (-70mv). While hyperpolarized, the neuron is in a refractory period that lasts roughly 2 milliseconds, during which the neuron is unable to generate subsequent action potentials.Hyperpolarization is often caused by efflux of K+ (a cation) through K+ channels, or influx of Cl– (an anion) through Cl– channels. On the other hand, influx of cations, e.g. Na+through Na+ channels or Ca2+ through Ca2+ channels, inhibits hyperpolarization. If a cell has Na+ or Ca2+ currents at rest, then inhibition of those currents will also result in a hyperpolarization.
2. it will be option c. the frequency of action potentials is directly related to the intensity of the stimulus.the stronger the stimulus, the higher the frequency at which action potentials are generated.the maximum frequency of action potentials is ultimately limited by the duration of the absolute refractory period. On the other hand, if the applied stimulus is only large enough to bring the neuron to threshold at rest, the maximum frequency of action potentials will now be governed by the total duration of the neuron refractory period (i.e., sum of the absolute and relative refractory periods).
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