Change in Membrane Potential From Axon Hillock to Axon

Values of Maximal Depolarization of Membrane Potential (mV) at Different Stimulation Voltages, by Location
Location	Stimulation Voltage
	0V (resting membrane potential)	2V	4V	6V	8V
Axon Hillock
Axon
Action Potential Generation
Action potential generated?	Minimum 3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.
Change in membrane potential with distance	Minimum 6 characters, one sign, four numbers, one digital full stop. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 6 characters, one sign, four numbers, one digital full stop. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 6 characters, one sign, four numbers, one digital full stop. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 6 characters, one sign, four numbers, one digital full stop. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 6 characters, one sign, four numbers, one digital full stop. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.

Graph 1. Maximal Depolarization of Membrane Potential at Axon Hillock and Axon After Different Stimulation Voltages

1. What was the resting membrane potential (no stimulation) recorded in Table 3?
2. At which stimulation voltage(s) did you see decrimental conduction of graded potential from axon hillock to axon?
3. At what stimulus voltage(s) did an action potential occur?
4. What was the membrane potential at the axon hillock when the action potential was generated?
5. For each of the stimulation voltages, indicate whether it was sub-threshold, threshold, or suprathreshold.
   • 2 V
   • 4 V
   • 6 V
   • 8 V

Effect of Supra-Threshold Stimulation Frequency on Action Potential Generation.

	Frequency of the Five Supra-Threshold Stimuli
	25 Hz	50 Hz	100 Hz	200 Hz	400 Hz
Number of Action Potentials Produced
Refractory period effect?	Minimum 2-3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 2-3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 2-3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 2-3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.	Minimum 2-3 characters, three letters. The Average value is valid, thank you. Sorry. Your value is wrong. Please try again. The valid Average value is correct, thank you.

Graph 2. Number of Action Potentials Generated At Different Times Between Simulations

6. State the amount of time between stimulations for each frequency of stimulation.
   • 25 Hz
   • 50 Hz
   • 100 Hz
   • 200 Hz
   • 400 Hz
7. For each frequency of stimulation, indicate whether the period between stimulation is longer or shorter than the length of an action potential. Length of action potential in pyramidal neuron is about 15-20 milliseconds (msec).
   • 25 Hz
   • 50 Hz
   • 100 Hz
   • 200 Hz
   • 400 Hz
8. Estimate the length of the refractory period for the pyramidal neuron.

1. In Experiment 1, discuss why the amplitude of the action potential did not increase as stimulation voltage increased above threshold.
2. In Experiment 1, explain why the membrane potential between the axon hillock and axon either changed or did not change with subthreshold stimulus. Differences of 1.0 mV or less are not significant.
3. In Experiment 1, explain why the membrane potential between the axon hillock and axon either changed or did not change with threshold stimulus. Differences of 1.0 mV or less are not significant.
4. In Experiment 2, explain why the number of action potentials generated varied with increased stimulation frequency.
5. Restate your predictions that were correct and give the data from your experiment that supports them. Restate your predictions that were not correct and correct them, giving the data from your experiment that supports the correction.

1. ECF potassium levels affect resting membrane potential. Hyperkalemia (excessive levels of potassium in the blood) and hypokalemia (abnormally low blood potassium levels) both affect the function of nerves and muscles.
   • Explain how hyperkalemia will initially affect the resting membrane potential and the generation of an action potential.
   • Explain how hypokalemia will initially affect the resting membrane potential and the generation of an action potential.
2. Tetrodotoxin, a toxin found in puffer fish, acts by inhibiting voltage-gated sodium channels. Eating improperly prepared puffer fish sushi can be fatal because of interference with action potential generation. Explain how tetrodotoxin interferes with action potential generation.