Question

Give the differences between impulse conduction in a myelinated nerve fibre and unmyelinated nerve fibre.

Answer 1

Hint: Nerve fibre is the axon part of a nerve cell or neuron. Neuron or nerve cell is the functional unit of Nervous system.

Complete Answer:
1. Myelinated nerve fibre:
- Myelinated nerve fibers contain the Myelin sheath.
- The Schwann cell wraps tightly around the nerve axon and forms the myelin sheath. These fibres appear as white in the fresh state. These fibres show nodes and internodes. These fibres occur in the white matter of the brain, spinal cord and in the central and cranium nervous system.

2. Unmyelinated nerve fibre:
Unmyelinated fibres do not contain myelin sheath. These fibres appear grey in the fresh state. These nerve fibres occur in the autonomic nervous system.

3. Impulse conduction in nerve fibre:
- Nerve impulse is a change that occurs in neurons due to the mechanical, chemical or electrical disturbances created by any stimuli.
- Nerve impulse propagates through an axon, synapse and neuromuscular junction, and this propagation is called impulse conduction in nerve fibre.

Differences between the impulse conduction in a myelinated nerve fibre and unmyelinated nerve fibre-

Sl.No.	Impulse conduction in myelinated nerve fibre	Impulse conduction in unmyelinated nerve fibre
1	In myelinated nerve fibre, impulse conduction is carried from node to node.	In unmyelinated nerve fibre impulse conduction carried along the length of axon.
2	In myelinated nerve fibre, action potential propagation requires activation of voltage gated Sodium channels only in nodal spaces.	In unmyelinated nerve fibres, action potential propagation requires activation of voltage gated sodium channels along the entire length of axon.
3	Action potential propagation in myelinated nerve fibres is much faster due to presence of Nodes of Ranvier.	Action potential propagation in unmyelinated nerve fibres is much slower due to the absence of Nodes of Ranvier.
4	Due to the presence of myelin sheath myelinated nerve fibres do not lose the impulse during conduction.	Unmyelinated nerve fibres can lose the nerve impulse during conduction.

Note: Conduction of nerve impulse is necessary in order to react against any stimuli. Because the disturbances caused by any stimulus goes to our brain through nerve cells and then we react against any stimuli.