Question

In a myelinated nerve fibre, the conduction of impulse is faster due to the presence of

• A. Pericytes.
• B. Endoneurium and epineurium.
• C. Myelin sheath and nodes of Ranvier.
• D. Nissl granules.

Answer 1

The correct option is C Myelin sheath and nodes of Ranvier.

The rate of impulse conduction in a nerve depends on the diameter of a fibre and the presence or absence of myelin.

Neurons with myelin conduct impulse much faster than those without myelin. Schwann cells (or oligodendrocytes) are located at regular intervals along the axons. Between areas of myelin are non-myelinated areas present, called as the nodes of Ranvier. Because fat (myelin) acts as an insulator, membrane coated with myelin does not conduct an impulse. So, in a myelinated neuron, action potentials only occur along the nodes and, therefore, impulses jump over the areas of myelin, going from node to node in a process called as saltatory conduction.