× Didn't find what you were looking for? Ask a question
Top Posters
Since Sunday
5
o
5
4
m
4
b
4
x
4
a
4
l
4
t
4
S
4
m
3
s
3
New Topic  
lws lws
wrote...
12 years ago
Please help.  I have yet to understand this lab.  I am in desperate need help.  I need answers for Exercise 3 Activities 1-8 Neurophysiology of Nerve Impulses.
Read 19280 times
4 Replies

Related Topics

Replies
wrote...
Staff Member
12 years ago
Activity 6: Testing the Effects of Curare (p. 37)

2. There is no change to the action potential tracing. Nerve propagation is unaffected because curare works on the synaptic ends of the nerve. Curare would ultimately kill the organism by blocking nerve transmission.

Activity 7: Testing the Effects of Lidocaine (p. 37)

1. No.

2. At threshold voltage, the screen still displays a flat line. Lidocaine is a sodium ion channel antagonist which will block sodium channels from opening, thus inhibiting any action potential from being generated.
- Master of Science in Biology
- Bachelor of Science
jwigginjr Author
wrote...
12 years ago
Eliciting a Nerve Impulse
Activity 1:  Electrical Stimulation

1.   Do you see any kind of response on the oscilloscope screen? At 1.0V there is no response
2.   What was the threshold voltage, or the voltage at which you first saw an action potential?       3.0V
3.   How does this tracing compare to the one that was generated at the threshold voltage? The slight increase in voltage results in a slight increase in the height of the action
potential peak. At threshold voltage, the smaller fibers in a nerve are stimulated and an action potential is seen.
4.   What reason can you give for the change? Increasing the voltage will cause most, if not all of the neural fibers to undergo
depolarization. A given nerve is made up of literally thousands of neuron processes (axons) so this slight increase is noted when all fibers in the nerve fire.
5.   Record this maximal voltage here:        4.0V

Activity 2:  Mechanical Stimulation

1.   When the glass rod is touching the nerve, what do you see on the oscilloscope screen? An action potential is generated when you touch the rod to the nerve.
2.   How does this tracing compare with the other tracings you have generated? The tracing is identical to the tracing generated at the threshold voltage.

Activity 3:  Thermal Stimulation

1.   What happens when the heated rod touches the nerve? An action potential is generated when you touch the heated rod to the nerve.
2.   How does this trace compare to the trace that was generated with the unheated glass bar? The tracing shows the action potential peaking slightly higher than the peak generated by the unheated rod.
3.   What explanation can you provide for this? Thermal stimulation can also cause a nerve response. Heat generates action potentials in more of the neurons in a nerve than are generated by touch.

Activity 4:  Chemical Stimulation

1.   Does the sodium chloride generate an action potential? Yes, sodium chloride generates an action potential.
2.   Does this tracing differ from the original threshold stimulus tracing?  If so, how? No, the tracing does not differ from the original threshold stimulus tracing.
3.   Does the hydrochloric acid generate an action potential?  Yes, the hydrochloric acid generates an action potential.
4.   Does this tracing differ from the original threshold stimulus tracing?  If so, how? No, the tracing does not differ from the original threshold stimulus tracing.
5.   To summarize your experimental results, what kinds of stimuli can elicit an action potential? Mechanical, thermal, electrical, and chemical stimulation are all capable of generating an action potential in a nerve.


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

1.   What sort of trace do you see? The screen displays a flat line, indicating no nerve response.
2.   What has happened to the nerve? The nerve has been anesthetized by the ether.
3.   How long does it take for the nerve to return to normal? About 6 minutes.

Activity 6:  Testing the Effects of Curare

1.   Does this generate an action potential? No
2.   What explains this effect? Nerve propagation is unaffected because curare works on the synaptic ends of the nerve.
3.   What do you think would be the overall effect of Curare on the organism? Curare would end up killing the organism by blocking nerve transmission.

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? The screen displays a flat line.
3.   Why does Lidocaine have this effect on nerve fiber transmission? Lidocaine is a sodium ion channel antagonist, which will block sodium channels from opening, inhibiting any action potential from being generated.

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? 8.85 m/sec
3.   Which nerve of the four has the fastest conduction velocity? Rat Nerve 2
4.   What was the speed of the nerve? 46.74 m/sec
5.   What is the relationship between nerve size and conduction velocity?  What are the physiological reasons for this relationship? The larger the nerve, the faster the conduction velocity. Conduction velocity is faster if the nerve is myelinated than if it not.
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? In myelinated nerves, conduction velocity is faster as the action potential jumps from node of Ranvier (internode) to node of Ranvier and does not travel along the cell membrane.
7.   What are the evolutionary advantages achieved by the myelination of neurons? Attack and escape. Myelinated neurons allow faster reflexes increasing chance of survival, which allows you to pass your genes on to your offspring.

CJTesch,  tick13mepinkk,  doseofmegan,  curlyy9,  brittneytay
wrote...
Donated
Trusted Member
12 years ago
I can't really tell, are these answers or questions Neutral Face
jwigginjr Author
wrote...
12 years ago
Lol....they are the answers the OP asked for the answers so I posted them. Maybe I should of stated it was the answers but I thought it was kind of obvious, sorry for any confusion.
New Topic      
Explore
Post your homework questions and get free online help from our incredible volunteers
  824 People Browsing
 115 Signed Up Today
Related Images
  
 1022
  
 334
  
 921
Your Opinion
Which is the best fuel for late night cramming?
Votes: 144

Previous poll results: Who's your favorite biologist?