R E V I E W S H E E T EXERCISE 3 NAME_________________________________ LAB TIME/DATE ________________________ Neurophysiology of Nerve Impulses Column B 1. Match each of the definitions in Column A with the appropriate term in Column B. Column A term that refers to a membrane potential of about 70 mv a. b. c. d. threshold sodium potassium resting membrane potential absolute refractory period depolarization eversal of membrane potential due to influx of sodium ions major cation found outside of a cell minimal stimulus needed to elicit an action potential period when cell membrane is totally insensitive to additional stimuli, regardless of the stimulus force applied major cation found inside of a cell e. f. 2. Fill in the blanks with the correct words or terms. Neurons, as with other excitable cells of the body, have two major physiological properties: __________________ and _________________.
A neuron has a positive charge on the outer surface of the cell membrane due in part to the action of an active transport system called the _______________________________. This system moves ____________________ out of the cell and _________________ into the cell. The inside of the cell membrane is negative, not only due to the active transport system but also because of __________________, which remain negative due to intracellular pH and keep the inside of the cell membrane negative. . Why don’t the terms depolarization and action potential mean the same thing? 4. What is the difference between membrane irritability and membrane conductivity? 37 38 Review Sheet 3 5. Why does a nerve’s action potential increase slightly when you add 1. 0 V to the threshold voltage and stimulate the nerve? 6. If you were to spend a lot of time studying nerve physiology in the laboratory, what type of stimulus would you use, and why? 7.
Why does the addition of sodium chloride elicit an action potential? 8. What was the effect of ether on eliciting an action potential? 9. Does the addition of ether to the nerve cause any permanent alteration in neural response? 10. What was the effect of curare on eliciting an action potential? 11. Explain the reason for your answer to Question 10. 12. What was the effect of lidocaine on eliciting an action potential? 13. What is the relationship between size of a nerve and conduction velocity? 14.
Keeping your answer to Question 13 in mind, draw an analogy between the nerves in the human body and electrical wires. Review Sheet 3 39 15. Hypothesize what types of animals would have the fastest conduction velocities. 16. How does myelination affect nerve conduction velocity? Explain. 17. In the nerve conduction velocity experiment, if any of the nerves used were reversed in their placement on the stimulating and recording electrodes, would there be any differences seen in conduction velocity? Explain.