What is the primary function of the myelin sheath?

• A. Receive stimuli
• B. Insulate the nerve and speed up conduction
• C. Store neurotransmitters
• D. Generate nerve impulses

Answer: (B)

The myelin sheath serves a crucial role in the nervous system by insulating the axons of neurons and enhancing the speed of electrical signal conduction. This fatty layer wraps around the axons, creating segments that allow for efficient transmission of action potentials. By insulating the nerve, the myelin sheath prevents the loss of electrical signals and facilitates saltatory conduction, where the action potential jumps between the Nodes of Ranvier. This process significantly increases the velocity of nerve impulses compared to unmyelinated axons, ensuring rapid communication between neurons.

The other options focus on different aspects of neuron function. While receiving stimuli is an important function, it is primarily associated with dendrites and sensory receptors rather than the myelin sheath. Storing neurotransmitters is a function related to synaptic vesicles found in the axon terminals, which is not involved in conduction speed. Generating nerve impulses pertains to the neuron’s action potential mechanisms, which occur at the level of the axon hillock and along the axon itself, rather than being a direct function of the myelin sheath.