Question

Non-myelinated axons differ from myelinated axons in that they are

A. Not sheathed in Schwann cells.

B. Not capable of regeneration after section.

C. Found only in the autonomic nervous system.

D. Less excitable.

E. Refractory for a longer ** after excitation.

Answer 1

A. False Both types have Schwann cell sheaths.

B. False Following section, the central end of the axon buds and grows down the Schwann cell sheath until it reaches its target organ.

C. False Some sensory fibres serving pain and temperature are unmyelinated C fibres.

D. True Myelinated fibres have a lower threshold for stimulation.

E. True 2 ms compared with 0.5 ms in well myelinated nerves; myelinated fibres can transmit impulses at higher frequencies than unmyelinated nerves.