Myelination and Saltatory Conduction

Question 0

Glia cells

Answer 0

• form insulating sheaths around some axons, with small gaps (Nodes in Ranvier) in between sheaths
• oligodendrocytes myelinate cells in the CNS
• Schwann Cells in PNS

Question 1

myelination and saltatory conduction

Answer 1

• increases the speed of the propagation of an Action Potential

Question 2

Electrical Conduction

Answer 2

• flow of electrons, like in an insulated wire
• occurs along myelinated segment
• but such signal degrades as it moves, needs to be re-boosted, periodically, to the original strength

Question 3

Nodes of Ranvier

Answer 3

where electrical signal triggers the slower but stronger ionic conduction

Question 4

Saltatory

Answer 4

= “Jumping”

nerve impulse in effect “jumps” from node to node as it is propagate along axon

increases overall speed of impulse from 1-10m/sec to 100-120 m/sec

Question 5

MS (Multiple Sclerosis)

Answer 5

• disease destroys myelin!
• in such un-insulated axons, electrical signal quickly degrades
• plus, since no Na+ gates under sheath, cell cannot resort to Ionic Conduction&raquo_space; CANNOT FIRE