Which of the following occurs at an excitatory synapse? A)There is increased permeability of the subsynaptic membrane to both Na⁺ and K⁺. B)A small hyperpolarization occurs. C) An action potential in the presynaptic neuron always causes an action potential in the postsynaptic neuron. D) Presynaptic neuron increases the permeability of the subsynaptic membrane of the postsynaptic cell to K⁺ only.

Question

Quizplus · Accepted Answer

At an excitatory synapse, there is increased permeability of the subsynaptic membrane to both Na+ and K+. This leads to depolarization of the postsynaptic neuron, making it more likely to fire an action potential. Option B is incorrect because a small depolarization occurs at an excitatory synapse, not hyperpolarization. Option C is incorrect because the generation of an action potential in the postsynaptic neuron depends on the magnitude of depolarization, which may or may not be sufficient to reach the threshold for firing an action potential. Option D is incorrect because the increased permeability of the subsynaptic membrane at an excitatory synapse is to both Na+ and K+.

Which of the Following Occurs at an Excitatory Synapse