Question

Explain the conduction of nerve impulse through a nerve fibre

Answer 1

Neurons or nerve cells generate impulses (chemical or electrical), that travel as waves of depolarization along the cell's membrane. Every neuron has a nerve cell body, dendrites and axons that propagate these impulses. Signal transmission is always unidirectional i.e., moving towards the nerve cell body along a dendrite or away from the nerve cell body along an axon.

There are two types of nerve fibres, myelinated and non-myelinated. In myelinated nerve fibre, the action potential is conducted from node to node in jumping manner. This is because the myelinated nerve fibre is coated with the myelin sheath. The myelin sheath is impermeable to ions. As a result, the ionic exchange and depolarization of nerve fibre are not possible along the whole length of the nerve fibre. It takes place only at some point, known as nodes of Ranvier. Whereas in non-myelinated nerve fibre, the ionic exchange and depolarization of nerve fibre take place along the whole length of the nerve fibre. Because of this ionic exchange, the depolarized area becomes depolarized and the next polarized area becomes depolarized.