Most of the neurons in the Autonomic Nervous System are

Ans: a (cholinergic) Ref: Ganong 22nd ed/ p.226Most of the neurons in ANS are cholinergic.Autonomic Nervous System:Parasympathetic preganglionic fibres have a long course.Parasympathetic postganglionic fibres have a short course. This is because the parasympathetic ganglions are located near the tissues it supplies.Each preganglionic axon diverges to an average of 8 or 9 postganglionic neurons.Preganglionic: Postganglionic = 1:8 or 9.Conduction speed in different fibres:* Autonomic preganglionic axons are B type* Autonomic postganglionic axons are C type* Conduction speed A>B>CPreganglionic fibres are myelinated, whereas, postganglionic fibres are unmyelinated.Cholinergic neuronso All preganglionic neuronso Parasympathetic postganglionic neuronso Sympathetic postganglionic neurons which innervate sweat glands and vessels in skeletal muscles.Remaining sympathetic postganglionic neurons are adrenergic or noradrenergic.Types of nerve fibresFibre typeFunctionsA alphaProprioception; somatic motorA betaTouch, pressureA gammaMotor to muscle spindlesA deltaPain, coId, touchBPreganglionic autonomicC- Dorsal rootPain, temperature, some mechano- reception, reflex responsesC - SympatheticPostganglionic sympathetic Relative susceptibility of nerve fibres Most susceptibleIntermediateLeast susceptibleHypoxiaBACPressureABCLocal anaestheticsCBA