Myelination increases the velocity of action potential...

Myelination increases the velocity of action potential propagation along an axon. What is myelination? Myelination causes clustering of voltage-gated $\mathrm{Na}^{+}$ channels and $\mathrm{Na}^{+} / \mathrm{K}^{+}$ pumps at nodes of Ranvier along the axon. Predict the consequences to action potential propagation of increasing the spacing between nodes of Ranvier by a factor of 10

Key Concepts

Saltatory Conduction

Saltatory conduction is the mechanism by which action potentials 'jump' from one node of Ranvier to the next along a myelinated axon. This method of propagation enhances the conduction velocity by limiting the regions where ionic exchange occurs, thereby reducing energy expenditure and increasing the efficiency of signal transmission.

Internodal Distance

Internodal distance refers to the length of the axon segment insulated by myelin between two successive nodes of Ranvier. Increasing the internodal distance excessively can lead to a scenario where the passive spread of the electrical signal decays too much before it reaches the next node, potentially resulting in conduction failure or a marked decrease in conduction velocity.

Myelination

Myelination is the process by which certain glial cells envelop axonal segments in a lipid-rich layer known as myelin, which serves as an electrical insulator. This insulation reduces the capacitance of the axonal membrane and increases its electrical resistance, resulting in significantly faster transmission of electrical signals along the nerve fiber.

Nodes of Ranvier

Nodes of Ranvier are gaps in the myelin sheath along axons that contain a high density of voltage-gated ion channels. These specialized regions enable the regeneration of the action potential by admitting ion flux, countering the passive decay of the electrical signal as it travels along the myelinated segments.

Transcript

Please give Ace some feedback