Nerve Condu ction is slow est in -
Ans. is 'a' i.e., C o The peripheral motor portions of the ANS are made up of two neurons: preganglionic and postganglionic neurons.o Preganglionic axons are small-diameter, myelinated, relatively slowly conducting B fibers.o A preganglionic axon diverges to an average of eight or nine postganglionic neurons.o In this way, autonomic output is diffused.o The axons of the postganglionic neurons are mostly unmyelinated C fibers and terminate on the visceral effectors.Fiber TypeFunctionFiber Diameter(m/m)Conduction Velocity (m/s)Splike Duration (ms)Absolute Refactory Period (ms)A aProprioception; somatic motor12-2070-120 bTouch, pressure5-1230-700.4-0.50.4-1gMotor to muscle spindles3-615-30 dPain, cold, touch2-532-30 BPreganglionic autonomic<33-151.21.2C Dorsal rootPain, temperature, some mechano-reception0.4-1.20.5-222SympatheticPostganglionic sympathetic0.3-1A0.7-2.322* A and B fibers are myelinated; C fibers are unmyelinated.
C
A alpha
A beta
A delta
Nerve Physiology