Anatomy Lab EXERCISE 3: Neurophysiology of Nerve Impulses

I got these from another post on this site.


1. C
2. -70
3. True
4. Potassium ions diffuse out across the membrane, leaving behind a net negative charge.
5. Membrane permeability to sodium is very low because there are only a few sodium leakage channels. Sodium ions do slowly diffuse inward, down their concentration gradient. Left unchecked, such inward leakage of sodium would eventually destroy the resting membrane potential.
The small inward sodium leak and outward leak of potassium leak are offset by the sodium potassium pumps.
6. The resting period potential is a potential difference between the inside of the cell and the outside of the cell across the membrane. It depends on the resting permeability of the membrane to ions and on the intracellular and extracellular concentrations of those ions to which the membrane is permeable.
7. Receptor
8. D
9. 40
10. Potassium Leak Channels
11. Graded potentials are short lived depolarizations or hyper polarizations of an area of a memb rane.
12. High pressure produced the largest amplitude receptor potential in the Pacinian corpuscle.
13. High chemical produced the largest amplitude potential in the olfactory receptors.
14. Photoreceptors
15. 20
16. True
17. C
18. Threshold applied to an action potential is the membrane voltage that must be reached to trigger an action potential.
19. Action potentials are triggered when enough depolarization accumulates to bring the membrane potential up to threshold.
20. It did not change, as the stimulus voltage was increased the peak value at R1 and R2 stayed at 100.
21. This means that there is either going to be enough stimulation to cause an action potential or there is not going to be enough stimulation, there is no in between. It is either going to happen or it is not.
22. Depolarizes
23. D
24. False
25. TTX irreversibly blocks voltage-gated sodium channels.
26. Lidocaine binds to voltage-gated sodium ions, and preven ts the flow of sodium ions. TTX irreversibly blocks voltage-gated sodium channels, which is why it is not used during dental procedures.
27. TTX blocks the propagations of the action potential from R1 to R2.
28. Lidocaine blocked the propagation of the action potential from R1 to R2.
29. A dentist would inject lidocaine into certain nerves of the mouth depending on where the pain is.
30. 1-2
31. D
32. True
33. It is the period immediately following the firing of a nerve fiber when it cannot be stimulated no matter how great a stimulus is applied.
34. The threshold for the second action potential increased when I decreased the interval.
35. This is because only partial repolarization has occurred, and only a greater than normal stimulus can cause an action potential to occur.
36. D
37. True
38. 1/62 Hz or 0.0161 Hz
39. When the intensity of the stimulus is increased, the size of the action potential does not become larger. Rather, t he frequency or the number of action potentials increases.
40. The threshold voltage changes by increasing in the relative refractory period, during this time a second action potential can be produced if the stimulus intensity is increased.
41. False
42. A
43. 50, 10, 1
44. Increases in axon diameter increase conduction velocity.
45. The amount of myelination affects the conduction velocity by more myelination the better the conduction velocity. 
46. The time between stimulation and the action potential differed because of the amount of myelination.
47. D
48. C
49. acetylcholine (ACh)
50. More synaptic vesicles went underwent exocytosis and were released.
51. Because the exocytosis of the synaptic vesicles is Ca2+- dependent, when the extracellular fluid contained no Ca2+, no neurotransmitter was released.
52. When Ca2+ ions were added to the extracellular fluid, a small amount of neurotransmitter was released.
53. False 54. -50
55. A

1. C

Can some one give me the answers to the charts/ tables in Activity's 6-9 in Ecsercise 3 and the Activity Questions? I have a week left of school and this is kicking my butt.  I would apperciate it so much!

PhysioEx Exercise 3:  Neurophysiology of Nerve Impulses

Activity 1:  The Resting Membrane Potential


            1. Excitability is the ability to transit nerve impulses to other neurons. (Points : 1) 
       True
       False
 
   
2. When a neuron is stimulated, the membrane becomes more permeable to Na+ ions, which diffuse into the cell, causing ___. (Points : 1) 
       depolarization
       hyperpolarization
       repolarization
 
   
3. As an action potential progresses, the permeability to Na+ decreases and the permeability to ____ increases. (Points : 1) 
       Ca2+
       K+
       Na+
 
   
4. The period of time when the neuron is totally insensitive to further stimulation and cannot generate another action potential is the ____. (Points : 1) 
       absolute refractory period
       membrane potential
       repolarization
       threshold
 
   
5. The resting membrane potential is the potential difference (electrical charge difference) between the inside of the cell and the outside of the cell across the cell membrane (Points : 1) 
       True
       False
 
   
6. What is the approximate concentration of K+ inside a typical cell? (Points : 1) 
       150 mM
       5 mM
       10 mM
       15 mM
 
   
7. What is the approximate concentration of K+  outside a typical cell? (Points : 1) 
       150 mM
       5 mM
       10 mM
       15 mM
 
   
8. What is the approximate concentration of Na+ inside a typical cell? (Points : 1) 
       150 mM
       5 mM
       10 mM
       15 mM
 
   
9. What is the approximate concentration of Na+ outside a typical cell? (Points : 1) 
       150 mM
       5 mM
       10 mM
       15 mM
 
   
10. In Activity 1, the intracellular voltage of the resting (control) neuron is _____ compared to the extracellular voltage. (Points : 1) 
       0
       -70
       -40
       + 10
 
   
11. Having a negative intracellular charge means that there are more negative charges than there are positive charges just inside the neuronal cell membrane. (Points : 1) 
       True
       False
 
   
12. Which of the following caused a change in membrane potential from -70 (in the control) to -40 in the cell body. (Points : 1) 
       an increase in extracellular K+
       a decrease in extracellular K+
       an increase in extracellular Na+
       a decrease in extracellular Na+
 
   
13. The end of the axon where it contacts the target is called the _____. (Points : 1) 
       cell body
       myelin sheath
       axon terminal
       nucleus
 
   
14. Neurotransmitter is released into the synaptic gap by ___. (Points : 1) 
       exocytosis
       voltage-gated neurotransmitter channels
       muscle contraction
       the postsynaptic membrane of the target cell
 
   
15. Exocytosis of neurotransmitter from the axon terminal is triggered by an increase of in the intracellular concentration of ___. (Points : 2) 
       Na+
       K+
       Ca2+
       none of the above
 
   
16. Neurotransmitter that has been released into the synpatic gap reaches the target by ___. (Points : 1) 
       exocytosis
       diffusion
       muscle contraction
       conduction down the axon
 
   
17. At the target, neurotransmitter _____. (Points : 1) 
       binds to receptor proteins
       causes membrane channels to open or close
       causes a change in membrane potential
 
 

EXERCISE 3:  Neurophysiology of Nerve Impulses



ACTIVITY 1:  The Resting Membrane Potential   Answers
1.   The nervous system contains two general types of cells: neuroglia cells and
a.   nerves.
b.   cell bodies.            
c.   neurons.
d.   nephrons.    C Neurons
2.   The resting membrane potential of the neuron in this lab under the control conditions was _______ mV.   -70
3.   True or False:  For most neurons, the concentration of  Na+ and K+ ions inside and outside the cell are the primary factors that determine the resting membrane potential.      True
4.   Explain why increasing the extracellular K+ causes the membrane potential to change to a less negative value.
   Potassium ions diffuse out across the membrane, leaving behind a net negative charge.
5.   Discuss the relative permeability of the membrane to Na+ and to K+ in a resting neuron.   Membrane permeability to sodium is very low because there are only a few sodium leakage channels. Sodium ions do slowly diffuse inward and down their concentration gradient. If you do not check for this then it could eventually destroy the resting membrane.
6.   Discuss how a change in Na+ or K+ conductance would affect the resting membrane potential.   The resting period potential is a potential difference between the inside of the cell and the outside of the cell across the membrane. It depends on the resting permeability of the membrane to ions and on the intracellular and extracellular concentrations of those ions to which the membrane is permeable.
ACTIVITY 3:  The Action Potential: Threshold
7.   In this lab simulation, what stimulus voltage first caused voltage to be seen at R1 and R2?     _______ mV   Action
8.   True or False:  A neuron must be polarized to the threshold voltage before an action potential is generated.       True
9.   If the resting membrane potential of a neuron is -70mV and the threshold voltage of that neuron is -50 mV, then the neuron must be depolarized by a minimum of ______ mV before an action potential is generated.
a.   10mV
b.   15mV                  
c.   20mV
d.   30mV   40
10.   Define the term threshold as it applies to an action potential.   It is the transmembrane potential at which an action potential begins.
11.   What change in membrane potential (depolarization or hyperpolarization) triggers an action potential?   Depolarization
12.   How did the action potential at R1 (or at R2) change as you increased the stimulus voltage above the threshold voltage?     It did not change.
13.   An action potential is an “all-or-nothing” event.  What does this mean?   All stimuli that bring the membrane to the threshold generate identical action potentials. The properties of the action potential are independent of the relative strength of depolarizing stimuli.
ACTIVITY 5:  The Action Potential: Measuring Absolute and Relative Refractory Periods
14.   According to your lab manual, voltage-gated Na+ channels inactivate (close) about _______ milliseconds after they open.   1-2
15.   During the absolute refractory period, a neuron would need to be depolarized by _____ mV before another action potential could be generated.
a.   50 mV
b.   75 mV   
c.   100 mV
d.   Another action potential cannot be generated   D
16.   True or False:  In this lab simulation, when the interval between stimuli was 7.5 msec and the stimulus voltage was 60 mV, a second action potential was seen.   True
17.   Define the absolute refractory period.   It is the period immediately following the firing of a nerve fiber when it cannot be stimulated no matter how great a stimulus is applied.
18.   How did the threshold for the second action potential change as you further decreased the interval between the stimuli?   The threshold for the second action potential increased when I decreased the interval.
19.   Why is it harder to generate a second action potential during the relative refractory period?   This is because only partial repolarization has occurred, and only a greater than normal stimulus can cause an action potential to occur.


         

Physioex 9.0 Exercise 3 pre and post quizzes Activity 7
Aug 24, 2012
Exercise 3: Neurophysiology of Nerve Impulses: Activity 7: The Action Potential: Conduction Velocity Lab Report
Pre-lab Quiz Results
You scored 100% by answering 5 out of 5 questions correctly.
1. An action potential can be propagated along an axon because there are __________ channels in the membrane.
You correctly answered: d. voltage-gated
2. The units of conduction velocity are
You correctly answered: d. meters/second.
3. Which of the following will affect axonal conduction velocity?
You correctly answered: c. both the diameter of the axon and the amount of myelination
4. Which of the following describes an A fiber?
You correctly answered: a. large diameter, heavily myelinated
5. Which of the following describes a C fiber?
You correctly answered: c. small diameter, unmyelinated

Post-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.
1. Action potential conduction velocity is fastest in which of the following fibers?
You correctly answered: a. A fibers
2. Action potential conduction velocity is slowest in which of the following fibers?
You correctly answered: c. C fibers
3. Why did the timescale have to be changed to measure the conduction velocity of the C fibers?
You correctly answered: b. The total time shown on the oscilloscope would have been too short to see the action potential at
R2.
4. The axons from touch fibers are A fibers, and the axons from pain fibers are C fibers. When you stub your toe, which
would you expect to perceive first?
You correctly answered: b. your toe touching something
 
Exercise 3: Neurophysiology of Nerve Impulses: Activity 8: Chemical Synaptic Transmission and Neurotransmitter Release
Lab Report
Pre-lab Quiz Results
You scored 100% by answering 5 out of 5 questions correctly.
1. The end of the axon where it contacts a target is called the
You correctly answered: c. axon terminal.
2. Neurotransmitter is released into the synaptic gap by
You correctly answered: a. exocytosis.
3. Exocytosis of neurotransmitter from the axon terminal is triggered by an increase in the intracellular concentration of
You correctly answered: c. Ca2+ .
4. Neurotransmitter released into the synaptic gap reaches the target cell by
You correctly answered: b. diffusion.
5. At the target, neurotransmitter
You correctly answered: d. does all of the above.

Post-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.
1. How is the neurotransmitter stored in the axon terminal before it is released?
You correctly answered: c. contained in synaptic vessicles
2. Are neurotransmitter molecules released one at a time or in packets?
You correctly answered: b. in packets
3. With the normal extracellular calcium concentration, [Ca2+ ], when the action potential reaches the axon terminal it
triggers
You correctly answered: b. release of neurotransmitter by exocytosis.
4. Comparing the low intensity stimulus to the high intensity stimulus, the high intensity stimulus causes
You correctly answered: b. more synaptic vesicles to undergo exocytosis


    PhysioEx 9.0 Exercise 3 Activity 8 Answers (1-5)

   May 6, 2012

Here is what I had...questions are included.

1. When the stimulus intensity is increased, what changes: the number of synaptic vesicles released or the amount of
neurotransmitter per vesicle?
Your answer:
The number of synaptic vesicles released increases as the stimulus intensity increases.
2. What happened to the amount of neurotransmitter release when you switched from the control extracellular fluid to the
extracellular fluid with no Ca2+ ? How well did the results compare with your prediction?
Your answer:
Because the exocytosis of the synaptic vesicles is Ca2+- dependent, when the extracellular fluid contained no Ca2+, no
neurotransmitter was released.
3. What happened to the amount of neurotransmitter release when you switched from the extracellular fluid with no Ca2+
to the extracellular fluid with low Ca2+ ? How well did the results compare with your prediction?
Your answer:
When Ca2+ ions were added to the extracellular fluid, a small amount of neurotransmitter was released.
4. How did neurotransmitter release in the Mg2+ extracellular fluid compare to that in the control extracellular fluid? How
well did the result compare with your prediction?
Your answer:
The neurotransmitter release was less when magnesium was added.
5. How does Mg2+ block the effect of extracellular calcium on neurotransmitter release?
Your answer:
Mg. will be oxidized to Mg2+. So instead of having Ca being the reducing agent, Mg will take its place. That is how blocking occurs.
Physioex 9.0 Exercise 3 pre and post quizzes Activity 9
Aug 24, 2012
Exercise 3: Neurophysiology of Nerve Impulses: Activity 9: The Action Potential: Putting It All Together Lab Report
Pre-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.
1. Sensory neurons respond to an appropriate sensory stimulus with a change in membrane potential that is
You correctly answered: b. graded with the stimulus intensity.
2. If the depolarization that reaches the axon is large and suprathreshold, the result in the axon is
You correctly answered: c. action potentials at higher frequency.
3. At the axon terminal, each action potential causes the release of neurotransmitter. This neurotransmitter diffuses to the
receiving end of an interneuron, where it binds to receptors and causes
You correctly answered: a. ion channels to open, so that the receiving end of the interneuron depolarizes.
4. Interneurons respond to chemical (neurotransmitter) stimulation with a change in membrane potential that is
You correctly answered: b. graded with the stimulus intensity

Post-lab Quiz Results
You scored 100% by answering 5 out of 5 questions correctly.
1. What determines the amplitude of the depolarization at the sensory receptor (R1)?
You correctly answered: a. The strength of the stimulus applied to the sensory receptor.
2. What determines the frequency of action potentials in the axon of the sensory neuron (R2)?
You correctly answered: a. The amplitude of the depolarization at the sensory receptor (R1).
3. Which of the following directly determines the amount of neurotransmitter released at the axon terminal of the sensory
neuron?
You correctly answered: c. The amount of calcium that enters the sensory receptor.
4. Which of the following directly or indirectly determines the amount of neurotransmitter released at the axon terminal of
the sensory neuron?
You correctly answered: d. All of the above play a role in determining the amount of neurotransmitter released.
5. Which of the following directly or indirectly determines the frequency of action potentials in the axon of the interneuron?
You correctly answered: d. All of the above play a role in determining the frequency of action potentials in the axon of the
interneuron.


liciting (Generating) a Nerve Impulse
1.    Why don't the terms depolarization and action potential mean the same thing?
A depolarization is any change in a neuron that makes it more positive than resting potential, but an action potential only occurs when the depolarization reaches the threshold level.

2.    What was the threshold voltage in Activity 1?
3.0 V

3.    What was the effect of increasing the voltage? How does this change correlate to changes in the nerve?
There was a slight increase

4.    How did the action potential generated with the unheated rod compare to that generated with the heated rod?
The action potential generated with the unheated rod was less than the action potential generated by the heated rod.

5.    Describe the types of stimuli that generated an action potential.
Electrical, mechanical, thermal, and chemical stimuli are all capable of generating an action potential.

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?
Although many different stimuli work, electrical stimulators are convenient because the voltage duration and frequency of the shock can be very precisely set for use.

7.    Why does the addition of sodium chloride elicit an action potential? Hint: Think about the sodium permeability of the neuron (Figure 3.2e).
While the sodium-potassium pump is pumping sodium out of the cell and potassium into the cell, these ions are leaking back where they came from by diffusion. By adding sodium chloride, a more-than-normal amount of sodium will diffuse into the nerve, causing the resting membrane potential to reach the threshold value, bringing about a membrane depolarization.

Inhibiting a Nerve Impulse
8.    What was the effect of ether on eliciting an action potential?
 There was no effect it conducted the same

9.    Does the addition of ether to the nerve cause any permanent alteration in neural response?
 No, the ether has no lasting effect.

10.    *What was the effect of curare on eliciting an action potential?


11.    *Explain the reason for your answer to question 10 above.
   

12.    *What was the effect of lidocaine on eliciting an action potential?

Nerve Conduction Velocity
13.    What is the relationship between size of the nerve and conduction velocity?
A larger nerve will have a faster conduction velocity.

14.    Keeping your answer to question 13 in mind, how might you draw an analogy between the nerves in the human body and electrical wires?
Larger electrical wire has less resistance to current flow and will conduct faster than smaller wire with increased resistance to current flow.

 15.    How does myelination affect nerve conduction velocity? Explain, using your data from Chart 1.
 Myelination speeds up nerve conduction velocity by causing the nerve impulse to jump across the cell membrane from one internode to another rather than be conducted across the entire cell membrane.

16.    If any of the nerves used were reversed in their placement on the stimulating and recording electrodes, would any differences be seen in conduction velocity? Explain.
No. Once a neural membrane is depolarized and the impulse is being conducted along the neural membrane, which direction is which does not matter. We state that a neural impulse is set up in the neuron's trigger zone (mainly due to the large number of sodium channels there) but once the depolarization is set up, it not only travels down the axon but also around the soma of the cell.