Lab 2: Neurophysiology of Nerve Impulses I

Lab 2: Neurophysiology of Nerve Impulses I

Activities 1-5

assignment:

1)responses to the questions specific to each activity that I provide below:

Activity 1: The Resting Membrane Potential

1. Draw a neuron making sure to include and label (dendrite, cell body,             nucleus, axon hillock, axon, myelin sheath, node of Ranvier, and show the                                     concentrations of Na⁺ and K⁺ both in the intracellular and in the                                           extracellular environment. You should be able to do this in Windows Paint, or any other program you choose. Note: You will not be graded on your artistic abilities, just accuracy of information.

Activity 2: Receptor Potential

2. Look up and describe the different stimuli types received by Pacinian,             Messiner’s, and Ruffini corpuscles as well as Merkel’s discs.

3. Did you find the “Judging from these results, does light have a smell?”                          question to be the craziest thing you’ve ever read?  If not, please tell me                              what beats it.

4 & 5. What does this Activity tell you about the perception of intense                                 stimuli?  Here’s the more important part of the question — how is the                                  perception of intense stimuli either similar or dissimilar to the muscular                             system with trying to move heavy objects (i.e. recruitment).  This question                                     will require some thought and is therefore worth two points.

Activity 3: The Action Potential: Threshold

6. When you set the single stimulus to 20mV, what type of signal was sent             — a graded potential or an action potential?

7. When varying the stimulus strength from 20mV to 50mV, why did you             not perceive any noticeable difference in response strength or velocity (i.e.                         how does this type of signal work)?  I’m looking for a very simple                                                response here.  It’s 5 words and I’ll give you the first and fifth.

An __________ _____________ _______________ response.

Activity 4: The Action Potential: Importance of Voltage-Gated Na+ Channels

8 & 9. Look up information regarding Lidocaine and Tetrodotoxin.  What                                       is the mechanism of action for each?  How are they similar and how                                    are they different?

Activity 5: The Action Potential: Measuring Its Absolute and Relative                                              Refractory Period

10. What type of channel is responsible for the hyperpolarization                                 phase of an action potential?  Be specific.

11. What is the relative refractory period?

12. What voltage was necessary to generate a second voltage at 60                                 millisecond intervals?
13. What was the maximum length of the refractory period?

2) lab write-up – write a brief summary regarding the Activities. This summary does NOT need to follow the “introduction, materials & methods, results, and discussion” format; rather, I would like you to explain what you learned from each activity in your own words.  For example, in some of the experiments, initially, no reaction will take place, but after manipulating a single variable and repeating the experiment, a reaction will happen. Then it will have you continue on and test other compounds, concentrations, strength of shock etc. etc. etc. and again, some will have a reaction, and some won’t.  I would like you to look at my recorded results for each activity ( That I have uploaded) and explain the underlying trends / processes that were being examined in the experiment(s).  Likely one small paragraph for each separate activity will suffice.