This chapter focuses on the roles of neurotransmitters and their receptors in anesthesia and pain modulation. Neurotransmitters, including acetylcholine, monoamines, amino acids, neuropeptides, purines, and gaseous molecules, are essential for signal transmission within the central nervous system (CNS). These chemical messengers, along with their receptors, mediate critical processes such as synaptic plasticity, sensory transmission, and motor control, which are directly influenced during anesthesia. The chapter highlights key receptor systems involved in the mechanisms of anesthesia, such as GABAergic and glutamatergic pathways, as well as their interactions in modulating pain perception. Neuromodulation, receptor clustering, and neurotransmitter-receptor dynamics are discussed as they relate to the efficacy of anesthetic agents and analgesics, providing insights into their roles in suppressing consciousness and altering pain pathways.