Final answer:
Serotonin modulates neurotransmission at the sensory-motor synapse through its interaction with receptors and its synthesis, release, and inactivation processes. Serotonin receptors belong to the G-protein-coupled receptor superfamily.
Step-by-step explanation:
Serotonin (5-HT) modulates neurotransmission at the sensory-motor synapse through its interaction with 5-HT receptors. Serotonin is synthesized from the amino acid tryptophan and is stored in vesicles in the presynaptic terminal. Its release is regulated by autoreceptors and it is inactivated by reuptake through the membrane carrier-protein 5-HT transporter (SERT). Serotonin receptors belong to the G-protein-coupled receptor superfamily and can have different functions depending on the specific receptor subtype.