Physioex neurophysiology of nerve impulses answers

PhysioEx Lab Report

PhysioEx Lab Report

Exercise 3: Neurophysiology of Nerve Impulses

Activity 7: The Action Potential: Conduction Velocity

Name: Aalwin Thomas

Date: 23 March 2021

Session ID: session-aabab984-54ee-f456-4a02-82a25f3a0cc0

Pre-lab Quiz Results

You scored 100% by answering 5 out of 5 questions correctly.

Experiment Results Predict Questions

An action potential can be propagated along an axon because there are _______ channels in the membrane.

You correctly answered: voltage-gated.

1

The units of conduction velocity are

You correctly answered: meters/second.

2

Which of the following will affect axonal conduction velocity?

You correctly answered: both the diameter of the axon and the amount of myelination.

3

Which of the following describes an A fiber?

You correctly answered: large diameter, heavily myelinated.

4

Which of the following describes a C fiber?

You correctly answered: small diameter, unmyelinated.

5

Predict Question 1: How will the conduction velocity in the B fiber compare with that in the A Fiber?

Your answer: The conduction velocity in the B fiber will be slower because the B fiber has a smaller diameter and less myelination.

1

Predict Question 2: How will the conduction velocity in the C fiber compare with that in the B Fiber?

2

3/23/2021 PhysioEx Exercise 3 Activity 7

https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex3/act7/# 2/5

Stop & Think Questions

Your answer: The conduction velocity in the C fiber will be slower because the C fiber has a smaller diameter and less myelination.

Note the difference in time between the action potential recorded at R1 and the action potential recorded at R2. The distance between these sets of recording electrodes is 2 centimeters (0.02 m).

Convert the time from milliseconds to seconds, enter the time (in seconds).

You answered: 0.002 sec.

1

Calculate the conduction velocity in meters/second by dividing the distance between R1 and R2 (0.02 m) by the time it took for the action potential to travel from R1 to R2.

Enter the conduction velocity.

You answered: 10 m/sec.

2

Note the difference in time between the action potential recorded at R1 and the action potential recorded at R2.

Convert the time from milliseconds to seconds, enter the time (in seconds).

You answered: 0.01 sec.

3

Calculate the conduction velocity in meters/second by dividing the distance between R1 and R2 (0.02 m) by the time it took for the action potential to travel from R1 to R2.

Enter the conduction velocity.

You answered: 2 m/sec.

4

Note the difference in time between the action potential recorded at R1 and the action potential recorded at R2.

Convert the time from milliseconds to seconds, enter the time (in seconds).

You answered: 0.1 sec.

5

Calculate the conduction velocity in meters/second by dividing the distance between R1 and R2 (0.02 m) by the time it took for the action potential to travel from R1 to R2.

Enter the conduction velocity.

6

3/23/2021 PhysioEx Exercise 3 Activity 7

https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex3/act7/# 3/5

Experiment Data

Axon Type Myelination Stimulus Voltage

(mV)

Distance From R1 to

R2 (m)

Time between

APs (msec)

Time between APs (sec)

Conduction Velocity (m/sec)

A fiber Heavy 30 0.02 2 0.002 10

B fiber Light 30 0.02 10 0.01 2

C fiber None 30 0.02 100 0.1 0.2

You answered: 0.2 m/sec.

3/23/2021 PhysioEx Exercise 3 Activity 7

https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex3/act7/# 4/5

Post-lab Quiz Results You have not completed the Post-lab Quiz.

Review Sheet Results How did the conduction velocity in the B fiber compare with that in the A Fiber? How well did the results compare with your prediction?

Your answer:

The results were equal to my answers.

1

How did the conduction velocity in the C fiber compare with that in the B Fiber? How well did the results compare with your prediction?

Your answer:

The results were equal to my answers.

2

What is the effect of axon diameter on conduction velocity?

Your answer:

The Conduction velocity will be greater if the axon diameter is large.

3

What is the effect of the amount of myelination on conduction velocity?

Your answer:

If the amount of myelination is great, then the Conduction velocity will be larger.

4

Why did the time between the stimulation and the action potential at R1 differ for each axon?

5

3/23/2021 PhysioEx Exercise 3 Activity 7

https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex3/act7/# 5/5

Your answer:

The time between the stimulation and the action potential at R1 differed for each axon because the diameter and the amount of myelination were varied.

Why did you need to change the timescale on the oscilloscope for each axon?

Your answer:

Change in timescale is necessary in order to see the action potentials. The velocity changes, so when it gets very slow we need a longer time scale.