Question

Conduction of nerve impulse through myelinated axon

Answer 1

NCERT based Answer for Class 11 Biology Students

Saltatory Conduction:

 In myelinated axons, myelin sheath acts as an electrical insulator to block ionic currents across the membrane.

 At intervals, nodes of Ranvier have voltage gated Na+ channels.

 When a nerve impulse propagates along a myelinated fiber, current flows through extracellular fluid surrounding the myelin sheath and through cytosol from one node to the next. But current flows across the membrane only at the nodes.

 Thus, membrane depolarization occurs only at nodes and the impulse appears to leap from node to node. This type of impulse conduction is called saltatory conduction.

 Since the impulse leaps from one node to next in saltatory conduction, it travels much faster than it would by continuous conduction in an unmyelinated fiber.

Note: Saltatory conduction is more energy efficient as less ATP is required for depolarization of nodes only as compared to every adjacent point in case of continuous conduction.  

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