Physio Ex Exercise 3 Activity 7 PDF

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2/21/2021

PhysioEx Exercise 3 Activity 7

PhysioEx Lab Report Exercise 3: Neurophysiology of Nerve Impulses Activity 7: The Action Potential: Conduction Velocity Name: Davin Nguyen Date: 21 February 2021 Session ID: session-65edca24-119a-4980-c19f-5f6106889da3

Pre-lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly. 1 An action potential can be propagated along an axon because there are _______ channels in the membrane. You correctly answered: voltage-gated. 2 The units of conduction velocity are You correctly answered: meters/second. 3 Which of the following will affect axonal conduction velocity? You correctly answered: both the diameter of the axon and the amount of myelination. 4 Which of the following describes an A fiber? You correctly answered: large diameter, heavily myelinated. 5 Which of the following describes a C fiber? You correctly answered: small diameter, unmyelinated.

Experiment Results Predict Questions 1 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. 2 Predict Question 2: How will the conduction velocity in the C fiber compare with that in the B Fiber?

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PhysioEx Exercise 3 Activity 7

Your answer: The conduction velocity in the C fiber will be slower because the C fiber has a smaller diameter and less myelination. Stop & Think Questions 1 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. 2 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. 3 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. 4 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. 5 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. 6 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. https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex3/act7/

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PhysioEx Exercise 3 Activity 7

You answered: 0.2 m/sec. 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

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PhysioEx Exercise 3 Activity 7

Post-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1 Action potential conduction velocity is fastest in which of the following fibers? You correctly answered: A fibers. 2 Action potential conduction velocity is slowest in which of the following fibers? You correctly answered: C fibers. 3 Why did the timescale have to be changed to measure the conduction velocity of the C fibers? You correctly answered: The total time shown on the oscilloscope would have been too short to observe the action potential at R2. 4 The axons from touch fibers are A fibers, and the axons from pain fibers are C fibers. When you stub your toe, which would you expect to perceive first? You correctly answered: your toe touching something.

Review Sheet Results 1 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 conduction velocity in the B fiber was much slower than with the A fiber. The results compared well with my prediction since the B fiber had a smaller diameter and was lightly https://media.pearsoncmg.com/bc/bc_0media_ap/physioex/10/ex3/act7/

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PhysioEx Exercise 3 Activity 7

myelinated than the A fiber. 2 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 conduction velocity in the C fiber was smaller compared to the B fiber. The results compared well with my prediction since the C fiber does not have myelin and is very thin as compared to the B fiber. 3 What is the effect of axon diameter on conduction velocity? Your answer: The effect is that as the axon diameter increases in size, the higher the conduction velocity is due to less resistance of the ion flow. 4 What is the effect of the amount of myelination on conduction velocity? Your answer: The effect of the amount of myelination is that the higher amount there is for myelin, the higher the conduction velocity. This is because there are fewer leakages of ions due to the insulation by myelin. 5 Why did the time between the stimulation and the action potential at R1 differ for each axon? Your answer: The time between stimulation and the action potential at R1 differed because each axon has a different diameter size and amount of myelination. 6 Why did you need to change the timescale on the oscilloscope for each axon? Your answer: The timescale needed to be changed because as conduction velocity slowed for the B fiber and the C fiber, it would take longer to record the action potential. Different increments are used since the B fiber was 10 times slower than the A fiber and the C fiber was 100 times slower than the A fiber.

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