#myelin sheath

• Unmyelinated — Lacking a myelin sheath; a nerve fiber or axon devoid of the protective, insulating structural lipid layer. Amielinic (unmyelinated) fibers (such as type C fibers) are characterized by a significantly slower nerve impulse conduction velocity compared to myelinated ones, playing an essential functional role in transmitting dull pain sensations, temperature, and regulating autonomic nervous system connections.
• Axon — A unique, long, and thread-like extension of a neuron, which has the fundamental structural and physiological role of conducting the efferent nerve impulse (action potential) away from the cell body (soma) toward other nerve, muscle, or glandular cells. This cellular component is delimited by the axolemma, contains axoplasm, and is often protected by an insulating myelin sheath, facilitating an ultra-fast, precise, and delicate transmission of bioelectric signals within the nervous system.