<prompt> Sympathetic system has adrenergic nerve endings at all sites except?HeaBlood vessels in skeletal musclesEyeNone  <response>: Ans. is b i.e., Blood vessels in skeletal musclesRef: Principles of medical physiologY p. 241Sympathetic adrenergic fibers are those which secrete endogenous catecholamines either adrenaline, nor-epinephrine nor-adrenaline or dopamineSome sympathetic fibers do not secrete catecholamines but secrete acetylcholine -Sweat glandsBlood vessels in skeletal muscles 