The Action Potential: Importance of Voltage-Gated Na+ Channels

Name: Christina Hale
Exercise 3: Neurophysiology of Nerve Impulses: Activity 4: The Action Potential: Importance of Voltage-Gated Na+ channels Lab Report
Pre-lab Quiz Results
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Experiment Results
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Experiment Data:

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Post-lab Quiz Results
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Review Sheet Results
1. What does TTX do to voltage-gated Na+ channels?
Your answer:
It irreversibly blocks voltage-gated Na+ channels.
2. What does lidocaine do to voltage-gated Na+ channels? How does the effect of lidocaine differ from the effect of TTX?
Your answer:
It reversibly blocks voltage-gated Na channels, unlike the TTX that does so irreversibly.
3. A nerve is a bundle of axons, and some nerves are less sensitive to lidocaine. If a nerve, rather than an axon, had been used in the lidocaine experiment, the responses recorded at R1 and R2 would be the sum of all the action potentials (called a compound action potential). Would the response at R2 after lidocaine application necessarily be zero? Why or why not?
Your answer:
Not necessarily because as it says in the first sensitive "some nerves are less sensitive to lidocaine" which means the axons found in those nerves might not be sensitive to the licodaine and hence the response at R2 "might" not be 0.
4. Why are fewer action potentials recorded at recording electrodes R2 when TTX is applied between R1 and R2? How well did the results compare with your prediction?
Your answer:
Because the TTX blocks the voltage-gated Na channels it prevents the production of action potentials at R2. My answer was
"TTX will block the response at R1 and R2." so I was partially right, it blocks the R2 but not the R1, since the TTX was added after it.
5. Why are fewer action potentials recorded at recording electrodes R2 when lidocaine is applied between R1 and R2?
How well did the results compare with your prediction?
Your answer:
It's the same as TTX. My response was "Lidocaine will block the response at R2 but have no effect at R1." so it compared well with the results.
6. Pain-sensitive neurons (called nociceptors) conduct action potentials from the skin or teeth to sites in the brain involved in pain perception. Where should a dentist inject the lidocaine to block pain perception?
Your answer:
It should be injected near the pain receptors, the nociceptors, in the gums.

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