Outline the basic steps of chemical synaptic transmission.

Outline the basic steps of chemical synaptic transmission.

• A. Action potential arrives → calcium influx → neurotransmitter release → neurotransmitter binds receptor → postsynaptic potential.
• B. Action potential arrives → calcium influx → neurotransmitter release → neurotransmitter binds receptor → postsynaptic potential → possible EPSP/IPSP.
• C. Neurotransmitter release → calcium influx → action potential → receptor binding.
• D. Postsynaptic potential → neurotransmitter release → action potential → receptor binding.

Answer: (A)

Chemical synaptic transmission starts when an action potential reaches the presynaptic terminal, opening voltage-gated calcium channels and allowing calcium to enter. The rise in calcium triggers vesicles to fuse with the presynaptic membrane and release neurotransmitter into the synaptic cleft. The neurotransmitter then binds to receptors on the postsynaptic membrane, leading to the opening of ion channels or activation of signaling pathways that change the postsynaptic membrane potential. This resulting change, which can be excitatory (EPSP) or inhibitory (IPSP), is the postsynaptic potential. The sequence ends with that postsynaptic potential, reflecting the outcome of transmitter action. The other options misplace steps or add extraneous steps (for example, suggesting a separate step after the postsynaptic potential or reversing the order of calcium entry and neurotransmitter release), which does not fit the established sequence of chemical synaptic transmission.

Chemical synaptic transmission starts when an action potential reaches the presynaptic terminal, opening voltage-gated calcium channels and allowing calcium to enter. The rise in calcium triggers vesicles to fuse with the presynaptic membrane and release neurotransmitter into the synaptic cleft. The neurotransmitter then binds to receptors on the postsynaptic membrane, leading to the opening of ion channels or activation of signaling pathways that change the postsynaptic membrane potential. This resulting change, which can be excitatory (EPSP) or inhibitory (IPSP), is the postsynaptic potential. The sequence ends with that postsynaptic potential, reflecting the outcome of transmitter action. The other options misplace steps or add extraneous steps (for example, suggesting a separate step after the postsynaptic potential or reversing the order of calcium entry and neurotransmitter release), which does not fit the established sequence of chemical synaptic transmission.