Question

In medullated nerve fibres nodes of Ranvier are

• A. areas found in stomach wall
• B. area of swelling on axons
• C. nodes formed in striated muscles
• D. areas where myelin sheath is absent on neuron

Answer 1

The Correct Option is D

Nodes of Ranvier have regularly spaced gaps in the myelin sheath around an axon of nerve fibre. The myelin sheaths as well the nodes were discovered by French pathologist and anatomist Louis Antoine Ranvier(1835-1922).The action potential "travels" from one place in the cell to another, but ion flow occurs only at the nodes of Ranvier. Hence, the action potential signal "jumps" along the axon, from node to node, rather than propagating smoothly, as they do in axons that lack a myelin sheath.