Physioex 3

965 words 4 pages
ACTIVITY 1: THE RESTING MEMBRANE POTENTIAL
1. Explain why increasing extracellular K+ reduces the net diffusion of K+ out the neuron through the K+ leak channels?
When the diffusion is greater on one side, the other side will slow down.

2. Explain why increasing extracellular K+ causes the membrane potential to change to a less negative value. How well did the results compare with your predictions?
There are two potassium's for every sodium so the increase of potassium will make it more negative. Prediction was correct.

3. Explain why a change in extracellular Na+ did not alter the membrane potential in the resting neuron?
The sodium channels are mostly closed during the resting state.

4. Discuss the relative
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Lidocaine is not always sensitive to the receptors and TTX causes irreversible damage. Lidocaine is slow at reacting and eventually wears off.

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?
No, because not all nerves are sensitive to lidocaine.

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?
Because it blocked the receptors, therefore it did not work as predicted.

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?
Because of the sensitivity to the drug, prediction correct.
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?
Inferior Alveolar Nerve

ACTIVITY 5: THE ACTION POTENTIAL: MEASURING ITS ABSOLUTE AND RELATIVE REFRACTORY PERIODS
1. Define inactivation as it applies to a voltage-gated sodium

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