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Jaykob101409 Jaykob101409
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Posts: 9
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12 years ago
2. The resting membrane potential of the neuron in this lab under the control conditions was _______ mV.

-70 Mv

4. Explain why increasing the extracellular K+ causes the membrane potential to change to a less negative value.

The concentration of K+ ions is highest inside the cell. If the extracellular concentration of K+ is increased, then the net diffusion of the K+ would decrease and the resting membrane potential (RMP) would become less negative.

5. Discuss the relative permeability of the membrane to Na+ and to K+ in a resting neuron.

 In a resting neuron, the permeability to K+ ions is higher than that of Na+ ions.

6. Discuss how a change in Na+ or K+ conductance would affect the resting membrane potential.

The resting membrane potential mostly is established by the relative concentrations of the Na+ and the K+ ions between the inside and outside of the cell. If conductance of these ions is changed, the RMP will change also.

14. What type of sensory receptor would likely respond to a green light?

A free nerve ending

18. Define the term threshold as it applies to an action potential.
 
The threshold voltage is the voltage at which you first observe an action potential.

33. Define the absolute refractory period.

 The absolute refractory period is the time period during which a neuron cannot fire a second AP, no matter how intense the stimulus.

34. How did the threshold for the second action potential change as you further decreased the interval between the stimuli?

 As the interval between stimuli was decreased, the threshold for the second AP will increase (requiring a larger depolarization.)

36. In the previous activities, you should have noticed that the amplitude (height) of the action potential

a. is always the same.
b. is an all-or-none event.
c. depends on the intensity of the stimulus.
d. Both a. and b. are true. Answer D

38. In this lab simulation, when the stimulus voltage was 30 Mv, the ISI was 62msec. This codes for an action potential frequency of _______ Hz.

1/62 Hz or 0.0161 Hz

40. How does the threshold voltage change during the relative refractory period?

 During the relative refractory period, the true threshold voltage stays the same, but because the neuron is hyperpolarized during that period, only a larger depolarization can result in an AP.

44. What is the effect of axon diameter on the conduction velocity?

 As the diameter of an axon increases, the conduction velocity also increases.

45. What is the effect of the amount of myelination on conduction velocity?

As the amount of myelination of an axon increases, the conduction velocity also increases.

46. Why did the time between stimulation and the action potential at R1 differ for each axon?

The time between stimulation and the recording of an AP depends on the conduction velocity of that fiber.

58. Identify the type of membrane potential (graded receptor potential or action potential) that occurred at R1, R2, R3, and R4 when you applied a moderate stimulus. (Compare/view the response to the stimulus.)

A graded stimulus was recorded at R1 and at R3; an AP was recorded at R2 and at R4.

Hope this helps someone Grinning Face
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wrote...
12 years ago Edited: 12 years ago, Farray
Thank you so much for the help! I wouldn't been able to answer this unless I pretty much begged my ta's for a more clear information that they were not able to provide since their brains were also as fried as ours were.
Jaykob101409 Author
wrote...
12 years ago
No problem I like to help whenever I can, and I always get help from here when I need it so I like to return the favor Grinning Face
wrote...
12 years ago
hi can anyone help me with physioex 9.0 review sheet 3 please
wrote...
Educator
12 years ago
hi can anyone help me with physioex 9.0 review sheet 3 please


Yes, post your questions in a new thread!
wrote...
12 years ago
sensory neuron have a resting potential based on efflux of potassium ion, what passive channels are likely found in the membrane of the the olfactory receptors in the membrane of the pacinian corpuscle and int membranne  of the free nerve ending
wrote...
12 years ago
"38. In this lab simulation, when the stimulus voltage was 30 Mv, the ISI was 62msec. This codes for an action potential frequency of _______ Hz.

1/62 Hz or 0.0161 Hz "
This is wrong.  First off, at 30mV the ISI is 60msec.  Secondly, you have to convert msec to seconds to calculate Hz, so 60msec = 0.060 sec so 1/.060 = 16.7 Hz (approx).

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