PhysioEx Lab Report
Exercise 3: Neurophysiology of Nerve Impulses Activity 3: The Action Potential: Threshold Name: Sara Ross Date: 3 February 2023
Session ID: session-73e8d1c0-4fe0-93d1-1e31-8379c0aad5b5
Pre-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly
1 Axons are
You correctly answered: long, thin structures that extend from a neuronal cell body
2 Which of the following is easier?
You correctly answered: Extracellular recordings of the action potential.
3 An action potential is usually initiated in an axon at or near
You correctly answered: all of the above
4 The initiation of an action potential in a sensory neuron in the body normally
You correctly answered: follows a sufficiently large depolarizing receptor potential.
Experiment Results Predict Question
1 Predict Question: How will the action potential at R1 (or R2) change as you continue to increase the stimulus voltage?
Your answer: The peak value of the action potential will increase.
Stop & Think Questions
1 Why is the action potential recorded by the second recording electrode (R2) delayed relative to the action potential recorded by the first recording electrode (R1)?
You correctly answered: The action potential had to propagate from R1 to R2
2 An increase in extracellular K*would depolarize a neuron. This depolarization would occur if
neurons were damaged. From what you have just learned about generating an action
potential, what effect would this have on nearby axons? The nearby axonal membranes will
You correctly answered: be depolarized to values near or above threshold voltages
Experiment Data
Stimulus Voltage (mv) 10
Peak VaIue at R1 (V)|Peak VaIue at R2 (V)
Action Potential
0
0
No Yes Yes Yes Yes
20 30
100
100 100
100
40
100
100
50
100
100
Stimulus Voltage = 10 mV
Voltage R1 (V) 70
100 Voltage R2 (V) snAWys
Time (msec)
Stimulus Voltage = 20 mV
Voltage R1 (V) 70
70 Voltage R2 (V) sn{hW},s
Time (msec)
Stimulus Voltage = 30 mV
100 Voltage R1 (V)
Time (msec)
Stimulus Voltage = 40 mV
Voltage R1 (V)
Time (msec)
Stimulus Voltage = 50 mV
Voltage R1 (V)
Time (msec)
Post-Iab Quiz ResuIts
You scored 10o% by answering 3 out of 3 questions correctly