PhysioEx Lab Report
Exercise 3: Neurophysiology of Nerve Impulses
Activity 6: The Action Potential: Coding for Stimulus Intensity
Name:
Date:
Session ID:
Pre-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.
1 The time after an action potential when a second action potential cannot be generated no matter
how intense the stimulus is called the
You correctly answered: absolute refractory period.
2 The time after an action potential when a second action potential can be generated only if the
stimulus intensity is increased is called the
You correctly answered: relative refractory period.
3 The term frequency refers to
You correctly answered: the number of action potentials per second.
4 The purpose of this activity is to explore
You correctly answered: the relationship between stimulus intensity and the frequency of action
potentials.
Experiment Results
Predict Question
1 Predict Question: What effect will the increased stimulus intensity have on the frequency of action
potentials?
Your answer: The frequency of action potentials will increase.
Stop & Think Questions
1 At the site of stimulation, the stimulus keeps the membrane of the axon at threshold for a long time,
but this depolarization does not spread to the recording electrode. After one action potential has
been generated and the axon has fully recovered from its absolute and relative refractory periods, the
stimulus is still present to generate another action potential.
Measure the time (in milliseconds) between action potentials. This interval should be a bit longer than
the relative refractory period (measured in Activity 5).
Select Measure to help determine the time between action potentials. A thin, vertical yellow line
appears at the first action potential. You can move the line in 10 millisecond increments by selecting
the + and - buttons beside the time display, which shows the time at the line. Subtract the time at the
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