SaltatoryConductionPrinzip

Saltatory conduction is the rapid transmission of action potentials along myelinated axons, in which the electrical impulse appears to jump from one node of Ranvier to the next. In vertebrates, myelin is formed by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system, wrapping the axon with multiple layers of membrane and lipids.

Mechanism: Action potentials are generated at nodes with high density of voltage-gated sodium channels. Myelin increases membrane resistance and decreases capacitance along the insulated segments (internodes). The depolarization travels passively from node to node, and when it reaches threshold at the next node, the action potential is regenerated.

Consequences: Saltatory conduction markedly increases conduction velocity compared with continuous conduction in unmyelinated fibers. It also reduces energy consumption because fewer ions cross the membrane, lowering the activity required by Na+/K+ pumps to restore ionic gradients.

Influencing factors: Velocity depends on axon diameter, degree of myelination, and internode length. Thicker myelin and larger diameter fibers conduct faster; proper spacing of nodes is crucial for reliable signaling. Demyelination, as in multiple sclerosis, disrupts saltatory conduction and impairs nerve function; remyelination can partially restore conduction.

Origin and significance: The concept arose from early 20th-century neuroscience studies of vertebrate nerves and remains a fundamental principle explaining how the nervous system achieves fast and energy-efficient signaling.