Need help please. BIOL 3408 Homework 3 NAME 100 80 60 40 1. The diameter of your

Question

Need help please.

BIOL 3408 Homework 3 NAME 100 80 60 40 1. The diameter of your sciatic nerve is about 8 microns. How many seconds does it take to travel from your spinal cord to your leg (about 1 Teleost Earthworm, median giant V Squid, giant Crab and crayfish, miscellaneous myelinated Cat, unmyelinated Lamprey 0.6 0.81 4 6 8 10 20 40 60 80100 200 500 1000 Axon diameter (um) on log scale Na+ channel Axon Myelin sheath Node A Node B Node C 2. The above figure from your textbook is a typical illustration of an axon wrapped with Schwann cells with nodes of Ranvier in between. In the above figure, the internodal length is about 40 mm and the internodal thickness (diameter) is about 9 mm. In reality, a mammalian motor neuron with an internodal length of 1.5 mm, would have an thickness (diameter) of about 18 microns. a. What is the ratio of internodal length to thickness for the figure? b. What is the ratio of internodal length to thickness for an actual neuron? c. In the figure, the total length is about 100 mm, What is the correct length of the figure in mm if the illustration was proportionately accurate to the the thickness of 9 mm. d. Convert the answer to meters, inches and feet.

Explanation / Answer

1. The diameter of a sciatic nerve is 8 microns. How much time does it take to travel from your spinal cord to your leg(about 1m)?

Diameter of a sciatic nerve = 8 microns.

From the above figure,

conduction velocity = 40m/s

Distance = 1m

Time = d / v

= 1/40

= 0.025sec.

The time is taken to travel from the spinal cord to leg is 0.025sec.

2.

a. What is the ratio of internodal length to thickness for the figure?

Ratio = Internodal Length/ thickness

= 40 mm / 9 mm

Ratio = 4.4 to 1

b. What is the ratio of internodal length to thickness for an actual neuron?

Ratio = Internodal length /thickness

Internodal length = 1.5mm

Thickness = 18 micron

1 micron = 0.001mm

18 micron = 0.018mm

Ratio =1.5 mm / 0.018 mm

= 83.3 to 1

c. In the figure, the total length is about 100 mm. What is the correct length of the figure in mm if the illustration was proportionately accurate to the thickness of 9 mm.

Vertical exaggeration = 9 mm / 0.018 mm

= 500

Correct length =distance is greater than 2 internodes

= 2*1.5 mm

= 3mm

Multiplying with vertical exaggeration = 500 X 3

Correct length = 1500mm.

d. Convert the answers into meters, inches, and feet.

1mm = 0.001 m

1500mm = 1.5m

1mm = 0.0393

1500mm = 59 inches

1 inch = 0.08333 foot

59 inch = 4.92 foot.

Millimetre metre inch foot 1500 1.5 59 4.92

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