myelin and synapse

myelin structure

wraps around section of axons

nodes of ranvier

gaps in-between myelin

where’s does AP occur (generate)

at the nodes of ranvier

NOT MYELIN

why does AP not occur at the myelin

myelin block all the VG Na+ channels 

how do action potentials travel across the axon

saltatory conduction.

saltatory conduction.

AP leaps from node to node

generation and regeneration of AP

after leaping from one node to another, the action potential regenerates at each node

myelin diseases do what

damage the myelins sheath

multiple sclerosis 

disease that affects axons @ CNS

gullian barre syndrome

disease that effects axons @ PNS

multiple sclerosis 

autoimmune diease

immune system destroys myelin in nuerons of the CNS

symptoms of multiple sclerosis 

vision, bladder & bowel problems 

fatigue, numbness, walking difficulties