A Postsynaptic Neuron Will Have an Excitatory Postsynaptic Potential (EPSP)

Question

A postsynaptic neuron will have an excitatory postsynaptic potential (EPSP) when
A) chemically regulated potassium channels are open and potassium is diffusing out of the cell.
B) more calcium ions than usual diffuse into the neuron.
C) chemically regulated sodium channels are open and sodium is diffusing into the cell.
D) the neuron is hyperpolarized.
E) more potassium ions than usual diffuse out of the neuron.

Accepted Answer

A postsynaptic neuron will have an excitatory postsynaptic potential (EPSP) when chemically regulated sodium channels are open and sodium ions are diffusing into the cell. This influx of positive charges will depolarize the membrane potential, making it more likely for the neuron to fire an action potential. Option A is incorrect because an efflux of potassium ions would cause hyperpolarization, not depolarization. Option B is incorrect because an influx of calcium ions would not directly depolarize the membrane potential. Option D is incorrect because hyperpolarization would be inhibitory rather than excitatory. Option E is incorrect because an efflux of potassium ions would cause hyperpolarization, not depolarization.