Which of the following statements most accurately describes the sequence of events leading to an Inhibitory Post-Synaptic Potential (IPSP) at a chemical synapse?
Correct: B
An IPSP (Inhibitory Post-Synaptic Potential) is a hyperpolarization or stabilization of the postsynaptic membrane potential, making it less likely for an action potential to fire. This is typically achieved by making the membrane potential more negative or closer to the equilibrium potential of K+ or Cl-.
Option A describes the mechanism for depolarization, often leading to EPSP if it's ligand-gated Na+ channels. Voltage-gated channels are more relevant to action potential propagation on the axon.
Option B correctly describes a common mechanism for IPSPs. When inhibitory neurotransmitters (e.g., GABA or glycine) bind to their receptors, they often open ligand-gated K+ channels. K+ ions then flow out of the cell (efflux) down their electrochemical gradient, making the inside of the cell more negative and thus hyperpolarizing the membrane.
Option C describes a mechanism for neurotransmitter release from the presynaptic terminal, not for IPSP generation on the postsynaptic membrane.
Option D describes the mechanism for an Excitatory Post-Synaptic Potential (EPSP), as Na+ influx causes depolarization.