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Active Potential Propagation
Colden-Stanfield
5
Biology
Professional
08/07/2008

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Cards

Term
What are the factors that detremine the rate of propagation of an action potential?
Definition

Passive properties of axonal membranes.

Space(Length) constant

Time constant

 

(they are only reflections of the physical properites of the neuronal membrane. Not directly dependant on metabolism or any voltage-dependant permeability changes.)

Term
Length(space) constant
Definition

λ= √(Rmd)/(Rl4)

Rm= membrane resistance(inversely proportional to permeability)

d= diameter of axon

Rl= longitudinal resistance

Distance it takes for depolarizing displacement to decay by 65% of it's initial value.

Term
Time constant
Definition

τ= RmCm

Rm= membrane resistance.(inversly proportional to permeability)

Cm= membrane capacitance that describes the ability of the membrane to store charge.

Term
Unmyelinated Nerve Fibers
Definition

Electrotonic Conduction

Conduction velocity is proportional to the diameter of the axon.

The larger the diameter o fthe axon, the greater the speed of propagation.

Term
Myelinated Nerve Fibers
Definition

Saltatory Conduction

The velocity of propagation is determined by the distance between the Nodes of Ranvier.

The greater the distance between the nodes, the greater the velocity of an action potential propagation.

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