This chapter discusses anesthesiology, where the characteristics of potent inhaled anesthetics include analgesia, amnesia and immobility. Advances in radiological guidance and now ultrasonic guidance have fostered an abundance of nerve blocks for chronic pain as well as for regional anesthesia as the sole or the adjunctive mode of surgical anesthesia. Patients undergoing surgery are subjected by definition to non physiological trespass that threatens to destabilize their homeostasis. Voltage-gated ion channels underlie the physiology of nerve and muscle, among others. Growth factor receptors, transmembrane guanylate cyclase-type receptors, and the nitric oxide system also contribute to the complex molecular pharmacology of receptor channels and signal transduction. Etomidate is a carboxylated imidazole dissolved in propylene glycol. Opioid bind to receptors located throughout the central nervous system and are potent analgesics as well as possessing a mild-to-moderate sedating effect. Local anesthetics are all weak bases. Anesthetic drugs, in particular, affect numerous receptors.