This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
In epidural analgesia morphine acts by acting on - 
Select and explain. 
A. Substantia gelatinosa, B. Axons, C. Ventral horn, D. Sensory nerve
A: Substantia gelatinosa
Answer: A: Substantia gelatinosa 
Explanation: Ans. is 'a' i.e., Substantia gelatinosa o Analgesic action of morphine has spinal and supraspinal components. It acts in the substantia gelatinosa of dorsal horn to inhibit release of excitatory transmitters from primary afferent carrying pain impulses.