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Which of the following statement is correct for node of Ranvier of nerve : -
A
Neurilemma is discontinuous
B
Myelin sheath is discontinuous
C
Both neurilemma and myelin sheath are discontinuous
D
Covered by myelin sheath
Detailed Solution
In a myelinated nerve fibre, the axon is covered by a myelin sheath formed by Schwann cells (in the peripheral nervous system).
The myelin sheath is not continuous; it has small gaps at regular intervals between adjacent Schwann cells. These gaps are the nodes of Ranvier.
The neurilemma (outer covering of the Schwann cells) remains continuous over the nodes.
The impulse jumps from node to node (saltatory conduction), which makes conduction much faster.
So at a node of Ranvier, the myelin sheath is discontinuous.
The myelin sheath is not continuous; it has small gaps at regular intervals between adjacent Schwann cells. These gaps are the nodes of Ranvier.
The neurilemma (outer covering of the Schwann cells) remains continuous over the nodes.
The impulse jumps from node to node (saltatory conduction), which makes conduction much faster.
So at a node of Ranvier, the myelin sheath is discontinuous.