Page 1 of 1: physiology--conduction velocities calculation.??

drkbravva · Credits: 24046 My Scrapbook My Reading List 1 Books

if the diameter of two unmyelinated axons differs by a factor of 2 ,their conduction velocities would differ by...
(1) a factor of 4
(2)--,,--------2
(3)-----,,----1
(4)----,,-----1.4

can some body give the formula for this one......pls....

draditithegreat · Credits: 1248000 My Scrapbook

it shud be 16 times..

soniadr25 · Credits: 2072 My Scrapbook

Answer should be (4), that means conduction velocities differ by a factor of 1.4

draditithegreat · Credits: 1248000 My Scrapbook

how is that sonia,can u tell us?
how is it in unmyelinated fibres?

decembermist · Credits: 41201 My Scrapbook

Is there any method to calculate it or any short cut

drkbravva · Credits: 24046 My Scrapbook My Reading List 1 Books

i have got this while searching net.....

see this ....

the condution velocity and diameter of th axon related to each other as

Radius, resistance and capacity

cv = sqrt(K a / 2 R_2 C_m)

Hodgkin and Huxley '52
cv : conduction velocity
K : 10470
a : radius of axis cylinder (238um)
R_2: specific resistance of axoplasm (35.4 Ohms)
C_m: capacity per unit of area of membrane (10^-6)

Show that a fixed value of K across axons implies that the conduction velocity Θ is proportional to the square root of axon radius a. This is theempirically-determined behavior of conduction velocity in unmyelinated axons.

CV1/CV2 = sqrt ( a1/a2)

we know that D=diameter=2 x radius(a)

i.e a=D/2

therefore, CV1/CV2 = sqrt ( D1/D2 )
Let D1=1
D2=2 ( since they differ by factor 2)

CV1/CV2 = sqrt ( 1/2)

CV1/CV2 = 1/sqrt2
= 1/1.41

MEANS that when there diameter's differs by factoer 2 then there conduction velosity differ by factor 1.41

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