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Home Q & A Board Biology-Related Homework Help Anatomy and Physiology
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pallakjj pallakjj
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10 years ago
I have some concerns regarding neurophysiology. Can anyone help me? Here are my questions...

1. If the sodium ion channels are blocked, are there any cations that're able to substitute for it?

2. Lidocaine and TTX both block the diffusion of sodium ions right? However, they differ in the sense that lidocaine is reversible while TTX is not? How so? How can Lidocaine's effect be reversible and TTX is irreversible?

3. In the PhysioEx Exercise 3 Activity 4 also. In the graph of the lidocaine and TTX, how come TTX blocked 3 gates while Lidocaine only blocked 2? There are 2 electrode recorder in the set up named R1 and R2 respectively, how come lidocaine and TTX blocked R2 and did not affect R1?

4. How come lidocaine and TTX only affects the sodium ion channel and not the potassium ion channel?

Hopefully you can answer my questions. Smiling Face with Open Mouth
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#1
Staff Member
Educator
10 years ago
Quote from: pallakjj (10 years ago)
I have some concerns regarding neurophysiology. Can anyone help me? Here are my questions...

1. If the sodium ion channels are blocked, are there any cations that're able to substitute for it?

2. Lidocaine and TTX both block the diffusion of sodium ions right? However, they differ in the sense that lidocaine is reversible while TTX is not? How so? How can Lidocaine's effect be reversible and TTX is irreversible?

3. In the PhysioEx Exercise 3 Activity 4 also. In the graph of the lidocaine and TTX, how come TTX blocked 3 gates while Lidocaine only blocked 2? There are 2 electrode recorder in the set up named R1 and R2 respectively, how come lidocaine and TTX blocked R2 and did not affect R1?

4. How come lidocaine and TTX only affects the sodium ion channel and not the potassium ion channel?

Hopefully you can answer my questions. Smiling Face with Open Mouth

Is this a PhysioEx inquiry? If so, what exercise # and activity # does is correspond to?
Mastering in Nutritional Biology
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pallakjj Author
wrote...
#2
10 years ago
It is a PhysioEx inquiry. It's from Exercise 3: Neurophysiology of the Nerve Impulses Activity 4: Importance of Voltage-Gated Sodium Channels
wrote...
#3
10 years ago
1. The sodium channels are voltage-gated sodium channels. Closure of the inactivation gate is a delayed response to the initial depolarization to threshold which closes the inactivation gate about 1 msec after sodium channels open.

2. Careful preparation of the pufferfish requires removal of the toxic portions that contain tetrodotoxin. The poison is most concentrated in the liver, ovaries and skin of the fish.

3. Calcium channels could possibly substitute for sodium channels to provide an influx of cation.
pallakjj Author
wrote...
#4
10 years ago
KaGi, I already have the answers. Thanks anyway... I was concerned as to the explanation of each answers.

Could Calcium ion channel possibly substitue for the sodium channels to provide influx? If yes, how so?

Also, I've attached a photo of the graph that I'm concerned about. It's the lidocaine and TTX effect on sodium ion channels. How come that in the graph, TTX blocked the propagation of nerve impulses on the third R2 while lidocaine have blocked starting on the fourth R2. What's the explanation between the two differences in the graph?
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#5
Staff Member
Educator
10 years ago
Quote from: pallakjj (10 years ago)
Could Calcium ion channel possibly substitue for the sodium channels to provide influx? If yes, how so?

HI again

I don't think so, calcium is a much larger element then sodium, so perhaps the channels are not optimized for the size difference, let alone the charge difference.
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pallakjj Author
wrote...
#6
10 years ago
So Padre, there would be no cation channel that are allowed to substitute for the sodium ion channels if ever they are blocked?
wrote...
#7
Staff Member
Educator
10 years ago
That I don't know, pallakjj. All I know is that if sodium channels were blocked, it would impair impulse conduction.
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