At an excitatory chemical synapse between two neurons, A) there is increased permeability of the postsynaptic cell to both Na⁺ and K⁺. B) a small hyperpolarization of the postsynaptic membrane occurs when the synapse is activated. C) an action potential in the presynaptic neuron always causes an action potential in the postsynaptic neuron. D) excitation occurs because K⁺ enters the postsynaptic cell. E) action potentials spread through gap junctions between cells.

Question

Quizplus · Accepted Answer

At an excitatory chemical synapse, there is increased permeability of the postsynaptic cell to both Na+ and K+. This increased permeability allows both ions to flow into the postsynaptic cell, depolarizing the membrane potential and leading to excitation. However, the influx of K+ is not the primary driver of excitation, as the influx of Na+ is much greater.

At an Excitatory Chemical Synapse Between Two Neurons