Question

Primary function of myelin sheath around vertebrate axon is to

• A. Regulate Na-K pump
• B. Increase in size of action potential
• C. Increase in speed of conduction by preventing leakage of nerve impulse
• D. Deactivate the release of neurotransmitter

Answer 1

Answer: (C)

Increase in speed of conduction by preventing leakage of nerve impulse

Most nerve fibres are surrounded by an insulating, fatty sheath called myelin, which acts to speed up impulses and prevent leakage. The myelin sheath contains periodic breaks called nodes of Ranvier. By jumping from node to node, the impulse can travel much more quickly than if it had to travel along the entire length of the nerve fibre.

Hence, the correct answer is (C)