Substance P C Fibres Dorsal Horn — FRCA Primary MCQ
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Correct answer: B — C fibre terminals in the substantia gelatinosa of the dorsal horn
Substance P is released from C fibre terminals (and some A-delta fibres) in the substantia gelatinosa (lamina II) of the dorsal horn. It acts at NK1 receptors facilitating pain transmission and central sensitisation. It is also released peripherally from sensory nerve terminals contributing to neurogenic inflammation (flare response). Aprepitant blocks NK1 receptors centrally.
Reference: Power Kam 2018 Principles of Physiology for the Anaesthetist