This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Adrenergic System, Subject name: Pharmacology
Pupil fails to dilate by giving cocaine in : 
Select and explain. 
A. Central sympathetic paralysis, B. Central parasympathetic paralysis, C. Peripheral parasympathetic paralysis, D. Peripheral sympathetic paralysis.
D: Peripheral sympathetic paralysis.
Answer: D: Peripheral sympathetic paralysis. 
Explanation: Ans. is 'd' peripheral sympathetic paralysis In periphery cocaine blocks the uptake of Adrenaline and Noradrenaline in Adrenergic Nerve ending* resulting in higher concentration of sympathetic neurotransmitters (Sympathomimetic effect):The peripheral sympathomimetic action of cocaine produces following effect:1. Mydriasis2. Rise in B.P.3. Local vasoconstriction4. TachycardiaTherefore if the peripheral sympathetic system is paralysed it will lead to reverse of the above mentioned actions.