TLS Online TPP Program

#Id: 5457

#Unit 7. System Physiology – Animal

The number of Na + channels per square micrometer of membrane in myelinated mammalian neurons has been estimated: 

50–75 in the cell body, 350–500 in initial segment, less than 25 on the surface of the myelin, 2000–12,000 at the nodes of Ranvier & 20–75 at the axon terminals 

TLS Online TPP Program

#Id: 5458

#Unit 7. System Physiology – Animal

The number of Na + channels along the axons of unmyelinated neurons, is about 110.

TLS Online TPP Program

#Id: 5459

#Unit 7. System Physiology – Animal

Depolarization in myelinated axons travels from one node of Ranvier to the next, this “jumping” of depolarization from node to node is called

saltatory conduction

TLS Online TPP Program

#Id: 5460

#Unit 7. System Physiology – Animal

Saltatory conduction is a rapid process that allows myelinated axons to conduct up to 50 times faster than the fastest unmyelinated fibers

TLS Online TPP Program

#Id: 5461

#Unit 7. System Physiology – Animal

Lioyd and Hunt, applies only to sensory nerve fibers and uses a Roman numeral nomenclature of I, II, III, and IV

TLS Online TPP Program

#Id: 5462

#Unit 7. System Physiology – Animal

Neurotrophins 

Necessary for survival and growth of neurons

In the CNS produced by astrocytes