Physio Ex Exercise 3 Activity 5 PDF

Preview

Summary

Physio Ex Exercise 3 Activity 5 The Action Potential: Measuring Its Absolute and Relative Refractory Periods...

Description

5/29/2021

PhysioEx Exercise 3 Activity 5

PhysioEx Lab Report Exercise 3: Neurophysiology of Nerve Impulses Activity 5: The Action Potential: Measuring Its Absolute and Relative Refractory Periods Name: Emily Mitchell Date: 29 May 2021 Session ID: session-a270c37d-738f-f45e-bed8-c40fa46a1773

Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1 Which of the following occurs after the peak of the action potential? You correctly answered: All of these occur. 2 What is meant by Na + channel inactivation? You correctly answered: The Na + channel no longer allows Na + ions to pass through it. 3 What happens when voltage-gated K + channels open? You correctly answered: All of these occur. 4 It is harder to generate a second action potential soon after the first action potential because You correctly answered: All of these make it harder to generate a second action potential.

Experiment Results Predict Question 1 Predict Question: If you further decrease the interval between the stimuli, will the threshold for the second action potential change? Your answer: The threshold for the second action potential will be higher (requiring a larger depolarization). Stop & Think Question 1 Threshold can be defined as the minimum voltage needed to generate an action potential. Is the threshold for the first action potential the same as, or different from, the threshold for the second action potential with a 60 msec interval? You correctly answered: The threshold for the first action potential is lower than the threshold for the second action potential. https://media.pearsoncmg.com/bc/bc 0media ap/physioex/10/ex3/act5/

1/7

5/29/2021

PhysioEx Exercise 3 Activity 5

Experiment Data Interval Between Stimuli (msec)

Stimulus Voltage (mV)

Second Action Potential?

250

20

Yes

125

20

Yes

60

20

No

60

25

No

60

30

Yes

30

30

No

30

35

No

30

40

No

30

45

Yes

15

60

Yes

7.5

60

Yes

3.75

60

No

https://media.pearsoncmg.com/bc/bc 0media ap/physioex/10/ex3/act5/

2/7

5/29/2021

https://media.pearsoncmg.com/bc/bc 0media ap/physioex/10/ex3/act5/

PhysioEx Exercise 3 Activity 5

3/7

5/29/2021

https://media.pearsoncmg.com/bc/bc 0media ap/physioex/10/ex3/act5/

PhysioEx Exercise 3 Activity 5

4/7

5/29/2021

https://media.pearsoncmg.com/bc/bc 0media ap/physioex/10/ex3/act5/

PhysioEx Exercise 3 Activity 5

5/7

5/29/2021

PhysioEx Exercise 3 Activity 5

Post-lab Quiz Results You scored 80% by answering 4 out of 5 questions correctly. 1 What is the original threshold for this neuron? You correctly answered: A 20 mV depolarization to -50 mV. 2 As the interval between stimuli decreases, the depolarization needed to generate the second action potential Your answer: decreases. Correct answer: increases. 3 Judging from your results, what time period after the first action potential best describes the relative refractory period (the time when a second action potential can be generated only if the stimulus intensity is increased)? https://media.pearsoncmg.com/bc/bc 0media ap/physioex/10/ex3/act5/

6/7

5/29/2021

PhysioEx Exercise 3 Activity 5

You correctly answered: 7.5-60 msec. 4 At what interval between stimuli did the second action potential fail, regardless of the stimulus intensity? You correctly answered: 3.75 msec. 5 What is the absolute refractory period for this neuron? You correctly answered: 3.75 msec.

Review Sheet Results 1 Define inactivation as it applies to a voltage-gated sodium channel. Your answer: When a cell can no longer diffuse Na+, inactivation occurs at the voltage gated sodium channels. 2 Define the absolute refractory period. Your answer: When you have a stimulus applied to a neuron, the time period where there is no room for a second action potential is called the refractory period. 3 How did the threshold for the second action potential change as you further decreased the interval between the stimuli? How well did the results compare with your prediction? Your answer: As the interval between stimuli was decreased, the threshold for the second action potential change increased. This is representative of an inverse relationship. My prediction was right. 4 Why is it harder to generate a second action potential during the relative refractory period? Your answer: During repolarization of the membrane from the voltage-gated K+ channels, the refractory period inhibits a second action potential until it gets depolarized again.

https://media.pearsoncmg.com/bc/bc 0media ap/physioex/10/ex3/act5/

7/7...