top-rated free essay

Physioex 8 Exercise 3

By ricolafamilia Mar 13, 2011 704 Words
Exercise 3: Neurophysiology of Nerve Impulses Worksheet
Assignment Due: Week 4

Student instructions: Follow the step-by-step instructions for this exercise found in your text and record your answers in the spaces below. Submit this completed document by the assignment due date found in the Syllabus.

Eliciting a Nerve Impulse
Activity 1: Electrical Stimulation

1. Do you see any kind of response on the oscilloscope screen? Just a flat line. 2. What was the threshold voltage, or the voltage at which you first saw an action potential? 3.0 V 3. How does this tracing compare to the one that was generated at the threshold voltage? Very similar except that it's peak is a little higher while it drops a little more as well. 4. What reason can you give for the change? The higher the voltage the more "excitable" the signal gets. 5. Record this maximal voltage here: 4.5 V

Activity 2: Mechanical Stimulation

1. When the glass rod is touching the nerve, what do you see on the oscilloscope screen? Another tracing. 2. How does this tracing compare with the other tracings you have generated? It is the same as the threshold trace at 3.0V.

Activity 3: Thermal Stimulation

1. What happens when the heated rod touches the nerve? It produces a trace. 2. How does this trace compare to the trace that was generated with the unheated glass bar? It is slightly more "excited" than the threshold trace but less than the maximum trace. 3. What explanation can you provide for this? Because of the heat on the bar the ions move faster than at room temperature.

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, it's the same. 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, it's the same. 5. To summarize your experimental results, what kinds of stimuli can elicit an action potential? Both Sodium Chloride and Hydrochloric acid elicit an action potential.

Inhibiting a Nerve Impulse
Activity 5: Testing the Effects of Ether

1. What sort of trace do you see? Flat line trace.
2. What has happened to the nerve? The ether stopped nerve fiber activity to function. 3. How long does it take for the nerve to return to normal? Elapsed time was 6.30 estimated.

Activity 6: Testing the Effects of Curare

1. Does this generate an action potential? Yes.
2. What explains this effect? It shouldn't elicit an action potential. Maybe it's caused by something else. 3. What do you think would be the overall effect of Curare on the organism? It should immobilize the organism.

Activity 7: Testing the Effects of Lidocaine

1. Does this generate a trace? No.
2. What sort of tracing is seen at the threshold voltage? Flat line trace. 3. Why does Lidocaine have this effect on nerve fiber transmission? Because it prevents the sodium channels from opening.

Nerve Conduction Velocity
Activity 8: Measuring Nerve Conduction Velocity

1. Which nerve in the group has the slowest conduction velocity? Earthworm 2. What was the speed of the nerve? 4.94msec with 8.70 conduction velocity. 3. Which nerve of the four has the fastest conduction velocity? Rat Nerve #2 4. What was the speed of the nerve? 0.94msec with 45.74 conduction velocity. 5. What is the relationship between nerve size and conduction velocity? What are the physiological reasons for this relationship? The result in conduction velocity depends on the size or diameter of the nerve. It is because one of the major physiological reasons of neurons is conductivity which is the ability to transmit the nerve impulse to other neurons, muscles, or glands. 6. Based on the results, what is your conclusion regarding the effects of myelination on conduction velocity? What are the physiological reasons for your conclusion? Based on the lab, it seems that myelinated nerves have faster conduction velocity. 7. What are the evolutionary advantages achieved by the myelination of neurons? It prevents grave and debilitating conditions on the body.

Cite This Document

Related Documents

  • Physioex 9.0 Exercise 3

    ...the membrane potential to change to a less negative value because the K+ ions diffuse out across the membrane. My results went well compared to my prediction because I predicted that the resting membrane potential would become less negative. 3. The extracellular Na+ did not alter the membrane potential in the resting neuron because the Na+ chan...

    Read More
  • Physioex 8.0 Exercise 3

    ...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? 3.0 V 3. How does this tracing compare to the one that was generated at the threshold voltage? The tracing travel in the same fashion but the tracing were different with an increase threshold vol...

    Read More
  • Physioex 8.0 Lab Exercise #3

    ...Exercise 3: Neurophysiology of Nerve Impulses Worksheet Assignment Due: Week 4 Student instructions: Follow the step-by-step instructions for this exercise found in your text and record your answers in the spaces below. Submit this completed document by the assignment due date found in the Syllabus. Please make sure that your answers ...

    Read More
  • Physioex 9.0 Exercise 3

    ...body 2. Which of the following caused a change in membrane potential from -70 to -40 in the cell body? a. An increase in extracellular K+ 3. Which of the following has the most negative voltage? a. Between the outside of the axon and outside the cell body with control K+ ECF b. Between the outside of the axon and outside the ...

    Read More
  • Physioex 3

    ...less negative. The results of my prediction were the same. 3. Explain why a change in extracellular Na+ did not alter the membrane potential in the resting neuron. There are less Na+ leak channels than K+ leak channels, and more of the K+ channels are open. 4. Discuss the relative permeability of the membrane to Na+ and K+ in a resting ...

    Read More
  • Physioex Cd Exercise 3 Nervous

    ...Eliciting (Generating) a Nerve Impulse 1. Why don’t the terms depolarization and action potential mean the same thing? Depolarization has to do with surfaces becoming more negative or positive and reaches a certain point called a threshold. When the threshold is reached, an action potential is initiated. 2. What was the threshold volta...

    Read More
  • Physioex 3

    ...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 mo...

    Read More
  • Physioex 8 Exercise 1

    ...Simple Diffusion Activity 1: Simulating Simple diffusion 1.What is the molecular weight of Na+? 22.9 2. What is the molecular weight of Cl-? 35.45 3. Which MWCO dialysis membranes allowed both of these ions through? 50, 100, and 200 4. Which materials diffused from the left beaker to the right beaker? Urea, NaCl an...

    Read More

Discover the Best Free Essays on StudyMode

Conquer writer's block once and for all.

High Quality Essays

Our library contains thousands of carefully selected free research papers and essays.

Popular Topics

No matter the topic you're researching, chances are we have it covered.