Exercise 3: Neurophysiology of Nerve Impulses Worksheet
Assignment Due: Week 4
Eliciting a Nerve Impulse
Activity 1: Electrical Stimulation
1. Do you see any kind of response on the oscilloscope screen? No 2. What was the threshold voltage, or the voltage at which you first saw an action potential? The threshold voltage is at 3.0 V. 3. How does this tracing compare to the one that was generated at the threshold voltage? There was a slight increase. 4. What reason can you give for the change? The increase in voltage. 5. Record this maximal voltage here: The maximal voltage is 4.0 V.
Activity 2: Mechanical Stimulation
1. When the glass rod is touching the nerve, what do you see on the oscilloscope screen? A spike on the screen. 2. How does this tracing compare with the other tracings you have generated? The tracing is identical to the tracing generated at the threshold voltage.
Activity 3: Thermal Stimulation
1. What happens when the heated rod touches the nerve? It stimulates the nerve. 2. How does this trace compare to the trace that was generated with the unheated glass bar? It’s similar to a 3.5 v stimulation. 3. What explanation can you provide for this? Heat stimulates nerves.
Activity 4: Chemical Stimulation
1. Does the sodium chloride generate an action potential? Yes 2. Does this tracing differ from the original threshold stimulus tracing? If so, how? No 3. Does the hydrochloric acid generate an action potential? Yes 4. Does this tracing differ from the original threshold stimulus tracing? If so, how? No 5. To summarize your experimental results, what kinds of stimuli can elicit an action potential? Thermal, glass, cold, hydrochloric acid and sodium chloride.
Inhibiting a Nerve Impulse
Activity 5: Testing the Effects of Ether
1. What sort of trace do you see? Flat line
2. What has happened to the nerve? The ether blocked the nerve transmissions. 3. How...
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